JP3949482B2 - Oscillator with temperature compensation function - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oscillator used in a wireless device or the like.
[0002]
[Prior art]
In recent mobile communication / multiplex radio apparatuses and the like, an oscillator of a radio unit becomes an important factor of reliability with respect to environmental conditions in addition to electrical characteristics. In particular, it is necessary to pay careful attention to fluctuations in the oscillation frequency and the output amplitude of the oscillator with respect to temperature. An oscillator is a circuit that generates a periodic signal without being given an external signal by sustaining a natural vibration of a passive circuit or a circuit composed of a passive circuit and an active circuit using the active circuit. In this oscillator, there are a negative resistance type oscillation circuit that uses an active element as a negative resistance element and a feedback type oscillation circuit that feeds back to a passive circuit using an amplification element. There is no difference.
[0003]
FIG. 16 is a diagram showing an oscillator using a negative resistance element. As shown in FIG. 16, the oscillator includes a resonator 2 and a negative resistance circuit 4. The resonator 2 is a circuit that mainly determines an oscillation frequency and vibrates at the oscillation frequency. The negative resistance circuit 4 is a circuit that supplies oscillation energy to the resonator 2. The reflection coefficient on the resonator 2 side measured from point A in the circuit shown in FIG._L, Input impedance Z_L, The reflection coefficient on the negative resistance circuit 4 side is Γ_in, Input impedance Z_inAnd
[0004]
The oscillation condition is expressed by the following formula (1).
[0005]
Γ_L・ Γ_in= 1 (1)
In this formula,
Γ_in= (Z_in-Z₀) / (Z_in+ Z₀(2)
Γ_L= (Z_L-Z₀) / (Z_L+ Z₀(3)
Substituting the relationship
Z_in+ Z_L= 0 (4)
Is obtained.
This
Re (Z_in+ Z_L) = 0 (5)
Im (Z_in+ Z_L) = 0 (6)
Equation (5) is referred to as an amplitude condition, and Equation (6) is referred to as a frequency condition.
[0006]
Actually, if the value on the left side of Equation (5) is 0 or more, the oscillation state is established.
Re (Z_in+ Z_L) ≧ 0 (7)
Equation (1) becomes
Γ_L・ Γ_in≧ 1 (8)
It can be.
[0007]
On the other hand, from equation (6)
-Im (Z_in) = Im (Z_L(9)
The oscillation conditions are easy to understand visually using the Smith chart. FIG. 19 shows Z_LAnd Z_in, And a certain impedance Z, the locus where −Im (Z) and Im (Z) are constant is plotted on the Smith chart. FIG. 17 shows Z within a certain frequency range including the oscillation frequency._LIt is the figure which showed on the Smith chart. FIG. 18 shows Z within a certain frequency range including the oscillation frequency._inIs a reciprocal display on the Smith chart to make it easier to visually understand the amplitude condition and frequency condition. FIG. 20 is a diagram for obtaining the oscillation condition based on the relationship of FIGS. Thus, in order to obtain a point satisfying the equation (6) for determining the oscillation frequency, as shown in FIG._LAnd the reciprocal Z_inHowever, it is good to obtain points (A and B in FIG. 20) that pass through the same imaginary part on the Smith chart.
[0008]
FIG. 21 is a diagram showing a grounded base oscillator. As shown in FIG. 21, the resonator 2 is a negative resistance oscillator including a tank circuit composed of an inductor L1 and a capacitor C1 connected in parallel and a capacitor C2 connected in series to the tank circuit. It is. The negative resistance circuit 4 includes a transistor Tr for supplying oscillation energy, Cce connected between a collector and an emitter of the transistor Tr for obtaining negative resistance characteristics, and Cb for grounding a base in an oscillation frequency band. Cbe serving as the base-emitter capacitance, R1 connected between the power source Vcc for providing the base voltage of the transistor Tr and the base of the transistor Tr, R2 connected between the base and the ground, and R3 determining the current of the transistor Tr Consists of
[0009]
In general, the characteristics of each circuit element constituting an oscillator vary with temperature. This change is Z_L, Z_inAs a result, the oscillation frequency fluctuates. In order to increase the stability of the oscillation frequency with respect to the temperature, it is efficient to apply a correction for the temperature change in a portion dominant to the oscillation frequency in the circuit.
[0010]
In general, an oscillator is adjusted so as to oscillate in the vicinity of a resonance point of a resonator having a sharp resonance characteristic in order to increase selectivity of an oscillation frequency. Z at this time_LThe amount of phase change with respect to frequency is Z_inIt can be seen that the oscillation frequency is dominated by the characteristics of the resonator. In other words, it can be said that the temperature characteristic of the resonator appears greatly as the temperature change of the oscillation frequency. Therefore, the temperature compensation uses a method in which an element for temperature compensation is embedded in the resonator. As a general temperature compensation element, a capacitor having a specific capacitance change rate is used.
[0011]
As described above, the oscillation frequency of the circuit of FIG. 21 is substantially determined by the resonance frequency of the inductor L1 and the capacitor C1. When the temperature changes, the characteristics of L1 and C1 change, the resonance frequency changes, and the oscillation frequency changes.
[0012]
FIG. 22 is a diagram showing a temperature compensation method using a capacitor. If the resonator of FIG. 21 has a characteristic that the resonance frequency decreases as the temperature increases, the oscillation frequency also decreases as the temperature increases as shown in FIG.
[0013]
FIG. 23 is a diagram illustrating an oscillator including a circuit that performs temperature compensation using a capacitor. In order to perform temperature compensation in this circuit, a temperature compensation capacitor Cs having a characteristic that the capacitance value decreases with increasing temperature is added to the resonator 2 as shown in FIG. 23, and the oscillation frequency is increased with increasing temperature. The resonator 2 is subjected to such an action as to raise it. At this time, since the resonance frequency is changed by adding the temperature compensation capacitor Cs, the value of the capacitor C1 is adjusted to another capacitor C1 ', and the original oscillation frequency is maintained. If the circuit of FIG. 21 has a characteristic that the oscillation frequency increases as the temperature rises, the capacitor Cs has a characteristic that increases the capacitance value with respect to the temperature rise, and acts to lower the oscillation frequency.
[0014]
FIG. 24 is a diagram showing a voltage controlled oscillator (VCO) including a temperature compensation circuit using a capacitor. The VCO can change the oscillation frequency by incorporating the varactor diode D in the resonator 16 and making the resonance frequency of the resonator 2 variable by the control voltage Vcont. In this circuit as well, temperature compensation can be performed by incorporating a temperature compensation capacitor Cs as in FIG.
[0015]
[Problems to be solved by the invention]
However, the temperature compensation of the oscillation frequency of the conventional oscillator has the following problems. In the conventional temperature compensation of the oscillation frequency by the capacitor, the capacitance change rate with respect to the temperature of the capacitor Cs must be selected to be optimum for the temperature change without compensation. That is, as the rate of change of the oscillation frequency due to temperature at the time of non-compensation is larger, it is necessary to select a capacitor having a larger rate of change in capacitance with respect to temperature for temperature compensation. However, in reality, capacitors having all temperature characteristics are not on the market, and capacitors having desired temperature characteristics do not exist or are extremely difficult to obtain. For this reason, it has been difficult to accurately perform temperature compensation.
[0016]
It is also conceivable to use a thermistor instead of a capacitor as a temperature compensation element in the resonator. When temperature compensation is performed using a resonator, there is a problem that if a thermistor that is a resistance component is used, the loss of the resonator increases and the Q value decreases. Further, the amplitude of the output of the oscillator fluctuates and is difficult to stabilize due to a change in the characteristics of the negative resistance circuit and a change in the characteristics of the output amplifier due to a temperature change.
[0017]
The present invention has been made in view of the above, and an object of the present invention is to provide an oscillator that can easily perform temperature compensation of the oscillation frequency of the oscillator and has a function of performing temperature compensation of the output amplitude of the oscillator. And
[0018]
[Means for Solving the Problems]
FIG. 1 shows the principle of the present invention. As shown in FIG. 1, the oscillator includes a resonator 20 and a negative resistance circuit 22. The resonator 20 is a circuit that resonates at an oscillation frequency. The negative resistance circuit 22 is a circuit that supplies energy to the resonator 20. The negative resistance circuit 22 has a temperature compensation circuit 24. When the temperature changes, the electrical characteristics of the components constituting the resonator 20 change, thereby changing the resonance frequency of the resonator 20 that determines the oscillation frequency of the oscillator. That is, the input impedance characteristic changes, and the oscillation frequency condition is satisfied. This will affect the oscillation frequency. The temperature compensation circuit 24 includes a thermistor 30 having a temperature characteristic that compensates for an oscillation frequency shift caused by a temperature change in the input impedance of the resonator 20 and maintains oscillation at a target frequency.
[0019]
As described above, the oscillation frequency of the oscillator depends on the input impedance Z of the resonator 20._LAnd the input impedance Z of the negative resistance circuit 22_inIs the frequency when Expression (6) is satisfied at the same frequency. When the temperature changes, the input impedance Z at the target oscillation frequency of the resonator 20_LChanges. Therefore, the thermistor 30 has an input impedance Z of the target oscillation frequency at each temperature within a predetermined range of the resonator 20._LAgainst Z_inHas a temperature characteristic that always satisfies the expression (6), so that temperature compensation is performed so as to oscillate at a target frequency in a predetermined range of temperature. As a result, temperature compensation can be performed using a thermistor instead of a capacitor, and since there are many variations of thermistors supplied to the market, temperature compensation can be easily performed.
[0020]
FIG. 25 shows the effect of this temperature compensation on a Smith chart using the method of FIG. The input impedance Z of the resonator 20 when the temperature changes within a predetermined range._LAnd the input impedance Z of the negative resistance circuit 22_LThe relationship was shown. The frequencies indicated by the inverted triangles on d1, d2, and d3 are as follows: d1 is a low temperature, d2 is a normal temperature, and d3 is an input impedance Z of the resonator 20 at a high temperature._LIndicates the target frequency. The frequencies indicated by the inverted triangles on e1, e2, e3 are as follows: e1 is at low temperature, e2 is at room temperature, and e3 is the input impedance Z of the negative resistance circuit 22 at high temperature._inIndicates the target frequency. At each temperature, Z_LAnd Z_inThey are on the same imaginary axis indicated by the points f1, f2, and f3 indicating the upper target frequency, and always satisfy Expression (6).
[0021]
DETAILED DESCRIPTION OF THE INVENTION
First embodiment
FIG. 2 is a diagram showing an example of the configuration of the oscillator according to the first embodiment of the present invention. Components that are substantially the same as those in FIG. 21 are denoted by the same reference numerals. As shown in FIG. 2, the oscillator includes a resonator 2 and a negative resistance circuit 50. The negative resistance circuit 50 includes a temperature compensation circuit 60, a transistor Tr that supplies oscillation energy, a Cce connected between the collector and the emitter of the transistor Tr, and a base grounded in the oscillation frequency band to obtain negative resistance characteristics. Cb, Cbe serving as a base-emitter capacitance, R1 connected between the power source Vcc for providing the base voltage of the transistor Tr and the base of the transistor Tr, R2 connected between the base and the ground, and the transistor Tr R3 is used to determine the current.
[0022]
The temperature compensation circuit 60 includes a capacitor Ct1, a thermistor TH1, and an offset resistor Rt1 connected in series between the collector of the transistor Tr and the ground. The capacitor Ct1 cuts the DC component and allows only the high frequency component to flow through the temperature compensation circuit 60, and at the same time, by combining with the thermistor TH1 and the offset resistor Rt1, the negative resistance characteristic can be obtained without changing the bias condition of the transistor Tr. It is for changing the temperature compensation. The thermistor TH1 oscillates at the target frequency by causing the characteristic of the negative resistance circuit 50 to follow the amount of change in the characteristic due to the temperature change of the resonator 2 so that the expression (6) is always satisfied at the target oscillation frequency. This is for performing temperature compensation. That is, the thermistor TH1 has an input impedance Z of the resonator 2 at the target oscillation frequency at a certain range of temperatures where the oscillator is used._LAnd the input impedance Z of the negative resistance circuit 50_inAs shown in FIG. 20, temperature compensation is performed so that the reciprocal of is located on an isoimaginary curve. The offset resistance Rt1 is used as an offset resistance when it is difficult for the thermistor TH1 to have an impedance above a certain level when impedance more than a certain level is required to perform temperature compensation. As a result, the selection range of the thermistor TH1 to be used can be expanded.
[0023]
Hereinafter, the operation of the circuit of FIG. 2 will be described.
[0024]
(1) Change in characteristics of resonator 2 due to temperature
FIG. 3 and FIG. 4 show changes in characteristics depending on temperatures at various temperatures (low temperature (−30 ° C.), normal temperature (25 ° C.), high temperature (70 ° C.), etc.) where the oscillator is used. FIG. 3 shows the input impedance Z of the resonator 2 at low temperature, normal temperature, and high temperature._LAre plotted on the Smith chart, and the frequencies indicated by a1, a2, and a3 are as follows: a1 is a low temperature, 2 is a normal temperature, and a3 is a target frequency at a high temperature. FIG. 4 shows the input impedance Z of the negative resistance circuit without temperature compensation in the same temperature range._inAre plotted on the Smith chart. The frequencies indicated by b1, b2, and b3 are b1 at a low temperature, b2 at a normal temperature, and a3 a target frequency at a high temperature. 3 and 4, Z_inShows that the variation with respect to temperature at the target frequency is extremely small, and as described above, the change in the oscillation frequency due to the temperature of the oscillator is mainly due to the characteristic change due to the temperature of the resonator.
[0025]
(2) Temperature compensation of negative resistance circuit
5 shows the input impedance Z of the negative resistance circuit 50 including the temperature compensation circuit 60 of FIG. 2 in the same temperature range as FIG._inAre plotted on the Smith chart, and the frequencies indicated by c1, c2, and c3 are c1 at a low temperature, c2 at a normal temperature, and c3 a target frequency at a high temperature. FIG. 6 is a superposition of FIG. 3 and FIG. It can be seen that the same effect as the principle diagram shown in FIG. 25 is obtained.
[0026]
(3) Effect of temperature compensation
FIG. 7 shows an oscillation frequency (F) when temperature compensation is not performed by the temperature compensation circuit 60 and when temperature compensation is performed in a temperature range of 0 to 70 ° C. in an actual oscillation circuit._T), The horizontal axis represents the temperature, and the vertical axis represents the target frequency (F₀). When the temperature compensation circuit 60 is not provided, the oscillation frequency fluctuates about 5 MHz in the range of 0 to 70 ° C., whereas when the temperature compensation circuit 60 is attached, the oscillation frequency is within about 1 MHz. I understand.
[0027]
As described above, according to the first embodiment, even if the characteristics of the resonator of the oscillator change due to a temperature change, the fluctuation of the oscillation frequency with respect to the temperature is reduced by adding the thermistor to the negative resistance circuit side. be able to. In addition, standard capacitors can be used for the resonator capacitor, and thermistors are clearly specified in the catalog, and there are many types of thermistors, making it easy to obtain thermistors with the desired temperature characteristics from the market. And easy to manufacture.
[0028]
Second embodiment
FIG. 8 is a circuit diagram of an oscillator according to the second embodiment of the present invention. Components that are substantially the same as those shown in FIG. 21 are denoted by the same reference numerals. As shown in FIG. 8, a temperature gain compensation circuit 90 is provided at the collector-emitter of the transistor Tr in the negative resistance circuit 70. Cce1 and Cce2 correspond to Cce shown in FIG. 21, and in combination with other capacitors (Cb, Cbe), negative resistance specification can be obtained at the target frequency.
[0029]
When the temperature changes, the input impedance Z of the negative resistance circuit 70_inChanges. Input impedance Z_inThis changes the energy supplied to the resonator 2, and the amplitude of the entire oscillation circuit varies. As a result, the amplitude of the output of the oscillator varies. When the amplitude of the output of the oscillator varies, the circuit connected to the oscillator may be affected. In particular, a decrease in amplitude tends to have an adverse effect. Therefore, the temperature gain compensation circuit 90 has a large power gain of the negative resistance characteristic regardless of the temperature, that is, Re (Z_in) Is temperature compensated so that it is a constant value without change in temperature.
[0030]
The temperature gain compensation circuit 90 includes a thermistor TH2 and an offset resistor Rt2 connected in series between the connection point of the capacitors Cce1 and Cce2 and the ground. The thermistor TH2 is the Re (Z of the negative resistance circuit 70._in) Is temperature-compensated so as to be constant regardless of the temperature change. The offset resistor Rt2 is provided for the same reason as the offset resistor Rt1 in FIG. The capacitor Cce1 is provided for the same reason as the capacitor Ct in FIG.
[0031]
FIG. 9 shows the input impedance Z of the negative resistance circuit 70 when only the resistance value of the thermistor TH2 of the negative resistance circuit 70 is changed to large, medium and small, and other parameters are made common._inThe power gain is plotted. The resistance values of the thermistor TH2 corresponding to the symbols a1, a2, and a3 in FIG. 9 are large, medium, and small. The thermistor TH2 increases as its resistance increases._inIt can be seen that the power gain is increased. Therefore, when the power gain of the negative resistance circuit 70 increases as the temperature increases, the resistance value of the thermistor TH2 is decreased. On the other hand, when the power gain of the negative resistance circuit 70 decreases as the temperature increases, the resistance value of the thermistor TH2 is increased. By using such a thermistor TH2, the power gain of the negative resistance characteristic can be made constant regardless of the temperature change.
[0032]
Although this embodiment has been described from the viewpoint of temperature compensation of the output amplitude of the oscillator, a circuit configuration for temperature compensation of the oscillation frequency of the first embodiment may be added to this embodiment. According to the second embodiment described above, temperature compensation of the output amplitude of the oscillator can be performed.
[0033]
Third embodiment
FIG. 10 is a circuit diagram of an oscillator according to the third embodiment of the present invention. Components that are substantially the same as those shown in FIG. 21 are denoted by the same reference numerals. As shown in FIG. 10, a temperature gain compensation circuit 120 is provided at the collector-emitter of the transistor Tr of the negative resistance circuit 100. Cce3 corresponds to Cce shown in FIG. 21, and can be combined with other capacitors (Cb, Cbe) to obtain negative resistance characteristics at the target frequency. The purpose of the temperature gain compensation circuit 120 is the same as that of the temperature gain compensation circuit 90 of the second embodiment. The temperature gain compensation circuit 90 of the second embodiment is composed of the thermistor TH2 and the offset resistor Rt3 connected in series between the connection point between the capacitor Cce1 and the capacitor Cce2 and the ground. The difference is that the gain compensation circuit 120 includes a thermistor TH3 and an offset resistor Rt3 connected in series with a capacitor Cce3 between a collector and an emitter. The temperature gain compensation circuit 120 includes a thermistor TH3 and an offset resistor Rt3. The thermistor TH3 performs temperature compensation so that the power gain of the negative resistance circuit 100 is constant regardless of the temperature change.
[0034]
FIG. 11 shows the input impedance Z of the negative resistance circuit 100 when only the resistance value of the thermistor TH3 of the negative resistance circuit 100 is changed to large, medium and small, and other parameters are made common._inThe power gain is plotted. The resistance values of the thermistor TH3 corresponding to the symbols b1, b2, and b3 in FIG. 11 are small, medium, and large. As the resistance of the thermistor TH3 decreases, Z_inIt can be seen that the power gain is increased. Thus, when the power gain of the negative resistance circuit 100 increases as the temperature increases, the resistance value of the thermistor TH3 is increased. On the other hand, when the power gain of the negative resistance circuit 100 decreases as the temperature increases, the resistance value of the thermistor TH3 is decreased. By using such a thermistor TH3, the power gain of the negative resistance characteristic can be made constant regardless of the temperature change. According to the third embodiment described above, there are the same effects as in the second embodiment.
[0035]
Fourth embodiment
FIG. 12 is a block diagram of an oscillator according to the fourth embodiment of the present invention. Components that are substantially the same as those in FIG. 21 are given the same reference numerals. In this embodiment, a temperature compensation circuit 170 is provided in the output circuit 160 of the negative resistance circuit 150 for temperature compensation so that the oscillation frequency becomes constant. The temperature compensation circuit 170 includes a thermistor TH4 and an offset resistor R4 connected in series between the emitter of the transistor Tr of the oscillator and the ground.
[0036]
FIG. 13 is a diagram showing the relationship between the resistance value of the resistor provided between the emitter and the ground (emitter load series resistance value: unit Ω) and the frequency variation Δf (oscillation frequency−target frequency: unit MHz). The parameters are constant. FIG. 13 shows that the oscillator oscillates at the target frequency when the emitter load series resistance is about 90Ω. As shown in FIG. 13, the oscillation frequency decreases as the emitter load series resistance value increases. Thus, the oscillation frequency of the oscillator can be changed by changing the emitter load series resistance value. As described above, when the temperature compensation is not performed, the oscillation frequency of the oscillator changes depending on the temperature. Therefore, by providing the thermistor TH4 having a temperature characteristic that compensates for the change, the oscillation frequency is controlled to be constant. . The offset resistor R4 has the same purpose as the offset resistor Rt1 in FIG. The buffer BUF is used to ensure isolation and an output level so that the negative resistance characteristic of the oscillator is not influenced by another circuit to which the oscillator is connected when the oscillator is connected to another circuit. . According to the fourth embodiment described above, temperature compensation can be performed using a thermistor in the output circuit of the negative resistance circuit, and thus the same effect as in the first embodiment can be obtained.
[0037]
Fifth embodiment
FIG. 14 is a block diagram of an oscillator according to a fifth embodiment of the present invention. Components that are substantially the same as those shown in FIG. 21 are denoted by the same reference numerals. In the present embodiment, a temperature compensation circuit 220 is provided in the output circuit 210 of the negative resistance circuit 200, and the purpose of this circuit is common to the temperature compensation circuit 170 of the fourth embodiment. The temperature compensation circuit 170 of the fourth embodiment has the thermistor TH4 and the offset resistor R4 connected in series between the emitter and the ground, whereas the temperature compensation circuit 220 of the fifth embodiment has the temperature compensation circuit 220 between the emitter and the ground. The difference is that a resistor R5 is provided in parallel with the resistor R6 and the thermistor TH5 connected in series, and a resistor R7 is provided in series with these circuits.
[0038]
This is because the combined resistance value of the temperature compensation circuit 170 of the fourth embodiment is the sum of the resistance values of the thermistor TH4 and the offset resistor Rt4, whereas the combined resistance value of the temperature compensation circuit 220 is the resistance R6 and the thermistor. The sum of the resistance of TH5, the sum of the resistance of resistor R5, and the sum of resistance R7, and the effect of the change in the resistance value of the thermistor TH5 on the change in the composite resistance value of the temperature compensation circuit 220 is This is larger than the influence on the change in the combined resistance value of the temperature compensation circuit 170. Therefore, even if the change amount of the resistance value due to the temperature change of the thermistor TH5 is small, the change amount of the combined resistance value of the temperature compensation circuit 220 can be increased, so that it becomes easy to obtain a desired combined resistance value at each temperature. is there.
[0039]
FIG. 15 is a diagram for explaining the effect of the temperature compensation circuit. For the compensation according to the fourth embodiment (compensation 1) and the compensation according to the fifth embodiment (compensation 2), the temperature (0 to 70 ° C.) is plotted on the horizontal axis. , Frequency deviation on the vertical axis ((oscillation frequency-target frequency) x 10⁶/ Target frequency, unit: ppm). As shown in FIG. 15, in the case of no compensation, the oscillation frequency decreases with temperature, but in the case with compensation 1, the amount of frequency change is small. It can be seen that the compensation amount 2 in which the variation amount of the combined resistance value of the temperature compensation circuit 220 is increased further reduces the variation amount and the compensation sensitivity can be adjusted. According to the embodiment described above, the same effect as that of the fourth embodiment can be obtained, and temperature compensation can be performed with high accuracy.
[0040]
The present invention includes the following supplementary notes.
[0041]
(Supplementary note 1) In an oscillator that has a resonator and a negative resistance circuit that supplies the resonator with the energy, and oscillates at a target frequency at a predetermined temperature,
A temperature characteristic for maintaining oscillation at the target frequency by compensating for a deviation in oscillation frequency caused by a phase change due to a temperature change of the reflection coefficient of the resonator as seen from a connection point between the resonator and the negative resistance circuit. An oscillator comprising a temperature compensation circuit including a thermistor having a negative resistance circuit side.
[0042]
(Supplementary note 2) The oscillator according to supplementary note 1, wherein the temperature compensation circuit is provided between a connection point between the resonator and the negative resistance circuit and a reference potential.
[0043]
(Supplementary Note 3) The negative resistance circuit includes a transistor, a feedback circuit that is connected to the output side of the resonator and supplies energy to the resonator, and a bias circuit that biases the transistor, and the temperature compensation circuit includes: The oscillator having a temperature compensation function according to claim 2, further comprising a capacitor, a thermistor, and an offset resistor for maintaining a bias condition for the transistor of the bias circuit.
[0044]
(Supplementary Note 4) A resonator, a transistor, a feedback circuit connected to the output side of the resonator and supplying energy to the resonator, a bias circuit for biasing the transistor, and an output circuit connected to the output side of the transistor In an oscillator that has a negative resistance circuit and oscillates at a target temperature at a predetermined temperature,
The reflection coefficient at the target frequency is constant by compensating for a change due to a temperature change within a predetermined temperature range of the reflection coefficient of the negative resistance circuit viewed from the connection point between the resonator and the negative resistance circuit. An oscillator comprising a temperature compensation circuit having a thermistor having such temperature characteristics in the feedback circuit.
[0045]
(Supplementary Note 5) The feedback circuit includes the transistor, the first and second capacitors connected in parallel to the transistor, and the connection point between the first and second capacitors and a reference potential. The oscillator according to appendix 4, which has a thermistor and an offset resistor.
[0046]
(Appendix 6) The oscillator according to appendix 4, wherein the feedback circuit includes a transistor and the thermistor and a capacitor connected in parallel to the transistor.
[0047]
(Appendix 7) A resonator, a transistor, a feedback circuit connected to the output side of the resonator and supplying energy to the resonator, a bias circuit for biasing the transistor, and an output circuit connected to the output side of the transistor And an oscillator that oscillates at a target temperature at a predetermined temperature.
An oscillator comprising a temperature compensation circuit including a thermistor having a temperature characteristic for compensating a deviation of an oscillation frequency from a target frequency due to a temperature change of a reflection coefficient of the resonator in an output circuit of the negative resistance circuit.
[0048]
(Supplementary note 8) The oscillator according to supplementary note 7, wherein the temperature compensation circuit includes the thermistor and an offset resistor provided between an output side of the transistor and a reference potential.
[0049]
(Supplementary Note 9) The temperature compensation circuit includes a first resistor and the thermistor connected in series to the output side of the transistor, a second resistor connected in parallel with the first resistor and the thermistor, and the first resistor. The oscillator according to appendix 7, wherein the oscillator has a third resistor provided between the reference potential and the reference potential.
[0050]
【The invention's effect】
According to the present invention described above, even if the characteristics of the resonator of the oscillator change due to a temperature change, the fluctuation of the oscillation frequency with respect to the temperature can be reduced by adding the thermistor to the negative resistance circuit side. In addition, standard capacitors can be used for the resonator capacitor, and thermistors are clearly specified in the catalog, and there are many types of thermistors, making it easy to obtain thermistors with the desired temperature characteristics from the market. And easy to manufacture.
[Brief description of the drawings]
FIG. 1 is a principle diagram of the present invention.
FIG. 2 is a configuration diagram of an oscillator according to the first embodiment of the invention.
FIG. 3 is a diagram showing a change in temperature characteristics of a resonator.
FIG. 4 is a diagram showing changes in negative resistance characteristics with temperature.
FIG. 5 is a graph showing changes in negative resistance characteristics with temperature.
FIG. 6 is a diagram showing the effect of temperature compensation of negative resistance characteristics.
FIG. 7 is a diagram showing the effect of temperature compensation according to the first embodiment.
FIG. 8 is a configuration diagram of an oscillator according to a second embodiment of the invention.
FIG. 9 is a diagram illustrating a power gain of a negative resistance due to a difference in resistance value of the thermistor.
FIG. 10 is a configuration diagram of an oscillator according to a third embodiment of the invention.
FIG. 11 is a diagram illustrating a power gain of a negative resistance due to a difference in resistance value of the thermistor.
FIG. 12 is a configuration diagram of an oscillator according to a fourth embodiment of the invention.
FIG. 13 is a diagram showing a change in frequency due to a difference in emitter load series resistance.
FIG. 14 is a configuration diagram of an oscillator according to a fifth embodiment of the invention.
FIG. 15 is an effect explanatory diagram of a temperature compensation circuit;
FIG. 16 is a diagram showing a configuration of a general negative resistance oscillator.
FIG. 17 Z_LIt is a figure which shows an example.
FIG. 18: 1 / Z_inIt is a figure which shows an example.
FIG. 19 Z_LAnd 1 / Z_inAnd -Im (Z) and Im (Z) are diagrams illustrating a trajectory in which Im (Z) is constant.
FIG. 20 is a diagram showing oscillation conditions.
FIG. 21 is a diagram illustrating a specific example of an oscillator.
FIG. 22 is a diagram illustrating a temperature compensation method using a capacitor.
FIG. 23 is a diagram illustrating an oscillator including a temperature compensation circuit using a capacitor.
FIG. 24 is a diagram showing a VCO including a temperature compensation circuit using a capacitor.
FIG. 25 is a diagram illustrating the principle of temperature compensation.
[Explanation of symbols]
20 Resonator
22 Negative resistance circuit
24 Temperature compensation circuit
30 thermistor

Claims (4)

A resonator, said biasing connected transistor and said transistor on the output side of the resonator, in the oscillator to have a negative resistance circuit including a bias circuit to which a power supply voltage is applied,
The negative resistance circuit is provided between the output side of the resonator to which the power supply voltage is applied and a predetermined voltage, and includes a temperature compensation circuit including a thermistor,
An oscillator wherein the thermistor changes with temperature so that an oscillation condition is maintained at the target frequency following a change in input impedance due to a temperature change at the target frequency of the resonator . The oscillator according to claim 1 , wherein the temperature compensation circuit includes a series circuit of a capacitor for removing a direct current component, an offset resistor, and the thermistor . A resonator, a transistor connected to the output side of the resonator, a bias circuit to which the transistor is biased and a power supply voltage is applied, and a plurality of transistors connected in series provided between a collector and an emitter of the transistor in oscillator have a negative resistance circuit including a capacitor,
The negative resistance circuit includes a temperature compensation circuit including a thermistor provided between one end of the plurality of capacitors connected to the collector of the transistor and the other end of the capacitor for removing a direct current component and the ground. Have
In the oscillator, the resistance of the thermistor changes with temperature so that an oscillation condition is maintained at the target frequency according to a change in input impedance due to a temperature change at the target frequency of the resonator . In an oscillator including a resonator, a transistor connected to an output side of the resonator, and a negative resistance circuit including a bias circuit that biases the transistor and to which a power supply voltage is applied.
The negative resistance circuit is provided between a collector and an emitter of the transistor, and includes a temperature compensation circuit including a capacitor and a thermistor for removing a direct current component,
In the oscillator, the resistance of the thermistor changes with temperature so that an oscillation condition is maintained at the target frequency according to a change in input impedance due to a temperature change at the target frequency of the resonator .

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