JPH0160965B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a half-wave rectifier circuit, and particularly relates to a half-wave rectifier circuit with high precision and good frequency characteristics [Prior Art] Conventionally, a sine wave is converted into a half-wave rectifier circuit. Various circuits for rectifying and outputting have been proposed, but all of them have the drawbacks of complex circuit configurations and poor frequency characteristics. Furthermore, the large number of resistive elements increases power consumption, making it difficult to integrate into an integrated circuit.

[Summary of the invention]

In view of the above points, the present invention was made to solve such problems and eliminate such drawbacks.The present invention has a simple circuit configuration, high precision, good frequency characteristics, and a small number of resistive elements. An object of the present invention is to provide a half-wave rectifier circuit that consumes low power and is easily integrated into an integrated circuit.

In order to achieve such an object, the present invention
, second and third current mirror circuits, and a speed-up diode for improving frequency characteristics, and this diode is connected to the third current mirror circuit.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First, before describing embodiments, an equivalent circuit of the present invention will be shown and explained in FIG. 1 in order to facilitate understanding of the present invention.

In FIG. 1, IN is an input terminal to which a sine wave signal is applied, and OUT is an output terminal from which an output signal is obtained. A is an operational amplifier, whose non-inverting input end (+) is connected to the input terminal IN through a capacitor C, and whose inverting input end (-) is connected to the operational amplifier through a rectifying element (diode) _D1 in the forward direction. It is connected to the output terminal of amplifier A and is also connected to the output terminal OUT via a resistor _R1 , and the output terminal of this operational amplifier A is connected to the output terminal OUT via a rectifying element (diode) _D2 in the forward direction. has been done. Further, this output terminal OUT is grounded via a resistor _R2 .

In the equivalent circuit of FIG. 1 constructed in this way, the sine wave signal applied to the input terminal IN is rectified by the diode _D1 , and only the positive half cycle of the input is obtained at the output terminal OUT. Figure 2 is a characteristic diagram showing its input/output characteristics, where a shows the waveform of the sine wave signal applied to the input terminal IN, and b shows the waveform of the output signal obtained at the output terminal OUT. It is something.

FIG. 3 is a circuit diagram showing an embodiment of a half-wave rectifier circuit according to the present invention.

In the figure, 1 is a non-inverting input terminal, and this input terminal is connected to a signal source SG via a capacitor C. 2 is an inverting input terminal, and this input terminal is connected to the output terminal 3 via a resistor _R1 .
This output terminal 3 is a terminal from which an output signal is obtained, and is grounded via a resistor _R2 . 4 is a power supply terminal connected to the positive side V _CC of the power supply, and 5 is a power supply terminal connected to the negative side V _EE of the power supply.

For Q ₁ and Q ₂ , the base and emitter are connected in common, and the emitter is connected to power supply terminal 4.
The PNP transistors constitute a first current mirror circuit. Q ₃ is an NPN transistor whose base is connected to non-inverting input terminal 1,
Its collector is connected to the collector and base of the PNP transistor _Q1 . Q ₄ and Q ₅ are PNP transistors whose bases and emitters are commonly connected, and whose emitters are connected to the power supply terminal 4, and these constitute a second current mirror circuit. Q ₆ is an NPN transistor whose base is connected to the inverting input terminal 2, and its collector is a PNP transistor.
Connected to the collector and base of transistor Q ₅ , the emitter of this NPN transistor Q ₆ is
It is connected to the emitter of the NPN transistor _Q3 , and is also connected to the power supply terminal 5 via the constant current source CCS.

The collector of Q ₇ was connected to power supply terminal 4, and the emitter was connected to the collector of PNP transistor Q _2.
In NPN transistor, this NPN transistor
Q ₇ corresponds to the rectifying element (diode) D ₁ shown in FIG.

Q ₈ has its base connected to output terminal 3, and its emitter connected to the base of NPN transistor Q ₇ and the collector of PNP transistor Q ₄ .
PNP transistor Q ₉ is an NPN transistor whose collector is connected to the collector of PNP transistor Q ₂ and its emitter is connected to power supply terminal 5. Q ₁₀ is an NPN transistor whose collector is connected to the collector of PNP transistor Q _{4 and} its emitter is connected to power supply terminal 5. Base of NPN transistor Q ₉ and base of PNP transistor Q ₈
This NPN transistor Q ₁₀ is connected to the collector of PNP transistor Q ₈
and NPN transistor _Q9 constitute a third current mirror circuit.

Q ₁₁ is an NPN transistor whose base is connected to the collector of the PNP transistor Q ₂ , whose collector is connected to the power supply terminal V _CC and whose emitter is connected to the output terminal 3 . This NPN transistor _Q11 corresponds to the rectifying element (diode) _D2 shown in FIG.

Next, the operation of the embodiment shown in FIG. 3 will be explained.

First, when a sine wave signal from the signal source SG is input to the non-inverting input terminal 1, the NPN transistor Q ₃ turns on when the positive half cycle of the sine wave is applied, and along with this, the PNP transistor Q ₁ turns on. , Q ₂ transitions to the on state. This PNP transistor _Q2
When turned on, the NPN transistor _Q11 turns on and the output is taken out to the output terminal 3. At the same time, a positive half-cycle signal is applied from the output terminal 3 to the inverting input terminal 2 via the resistor R ₁ , so the NPN transistor Q ₆ turns on, and along with this, the PNP transistors Q ₄ , _Q5 both transition to the on state.

Then, in the next negative half cycle of the sine wave,
NPN transistor _Q3 is turned off and along with this
PNP transistors Q ₁ and Q ₂ also turn off. At the same time, the NPN transistor Q ₆ also turns off, and accordingly, the PNP transistors Q ₄ and Q ₅ turn off, and the collector potentials of the PNP transistors Q ₂ and Q ₄ swing negative. During the transition from this point to the next half cycle, if NPN transistor Q ₇ is not present, there will be a delay in the potential relationship between PNP transistor Q ₂ and PNP transistor Q ₄ , resulting in poor followability and frequency characteristics. deteriorates.

On the other hand, when NPN transistor Q ₇ is present, the relationship of V _CQ2 < V _CQ4 is always maintained due to the on-state of NPN transistor Q ₇ , and the collector potential of PNP transistor Q ₄ increases at the point in time when moving toward the positive half cycle. This has the advantage of faster speed and improved frequency characteristics. Note that V _CQ2 and V _CQ4 are collector potentials of PNP transistor Q ₂ and PNP transistor Q ₄ , respectively.

In addition, due to the circuit operation, when stable, PNP transistor Q ₈ and PNP transistor Q ₂
The collector potentials of PNP transistor _Q4 will be the same.

In other words, when viewed from the output terminal 3 side, the collector potential V _CQ4 of the PNP transistor Q ₄ is equal to the output potential V _O
Then, V _CQ4 = V _O +V _BEQ8 , and similarly, V _CQ2 = V _O + V _BEQ11 . Here, V _BEQ8 and V _BEQ11 are
These are the base-emitter potential of the PNP transistor _Q8 and the base-emitter potential of the NPN transistor _Q11 .

Then, V _BEQ8 V _BEQ11 becomes V _CQ4 V _CQ2 , and the base-emitter potential V _BEQ7 of NPN transistor Q ₇ becomes almost zero, and in the stable period, NPN
Transistor _Q7 does not work, and its effective operation is not restricted by this NPN transistor _Q7 .

In addition, in the embodiment shown in FIG. 3 above,
I explained using the case of NPN input type as an example, but
The present invention is not limited to this, but PNP
The same applies to input types. In addition, the rectifier
Although the case where an NPN transistor is used as _D1 has been described as an example, the present invention is not limited to this, and any type of PN junction may be used.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, high performance can be achieved by a simple configuration of providing the first to third current mirror circuits and a speed-up rectifying element without using complicated means. A half-wave rectifier circuit can be obtained, and since the number of resistive elements is small, the power consumption is low, and the circuit can be easily integrated, so that the practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is an equivalent circuit diagram of the present invention, FIG. 2 is an input/output characteristic diagram of the equivalent circuit of FIG. 1, and FIG. 3 is a circuit diagram showing an embodiment of a half-wave rectifier circuit according to the present invention. Q ₁ , Q ₂ ...PNP transistor, Q ₃ ...NPN
Transistor, Q ₄ , Q ₅ ...PNP transistor,
Q ₆ , Q ₇ ... NPN transistor, Q ₈ ... PNP transistor, Q ₉ ~ _{Q 11} ... NPN transistor,
CCS...constant current source.

Claims (1)

[Claims] 1 A first current mirror circuit constituted by first and second transistors of the same polarity, whose bases and emitters are connected in common and whose emitters are connected to the positive side of a power supply; a third transistor of different polarity connected to the collector of the transistor and having an input signal supplied to its base; and a third transistor of the same polarity, the base and emitter of which are connected in common, and the emitter of which is connected to the positive side of the power supply. a second current mirror circuit constituted by a fourth transistor and a fifth transistor, a collector connected to the collector of the fifth transistor, an emitter connected to the emitter of the third transistor, and a constant current source; a sixth transistor of a different polarity, which is connected to the negative pole side of the power supply through the base and whose base is supplied with an output signal; a seventh transistor of a different polarity whose emitter is connected to the collector of the fourth transistor, an eighth transistor of the same polarity whose emitter is connected to the collector of the fourth transistor, and a collector of which is connected to the collector of the second transistor. a ninth transistor of a different polarity, the collector of which is connected to the fourth transistor;
a tenth transistor of different polarity, whose emitter is connected to the negative electrode side of the power supply and whose base is connected to the collector of the eighth transistor;
a third current mirror circuit comprising a transistor of different polarity, the collector of which is connected to the positive side of the power supply, the emitter of which is connected to the output terminal, and the base of which is connected to the collector of the second transistor; A half-wave rectifier circuit comprising an eleventh transistor.