JP3443382B2 - Amplifier circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-bias type amplifying circuit which is composed of an inverter and a transmission gate circuit for a feedback resistor in a MOS device and self-biased by a feedback resistor to perform an amplifying operation. The present invention relates to a circuit that reduces a change in feedback resistance value.

[0002]

2. Description of the Related Art Generally, in a self-bias type amplifier circuit, as shown in FIG. 2, an output signal is inverted with respect to an input signal.
It is composed of an inverter 21 using an OS device, and a transmission gate 22 in which a source and a drain of a P-channel MOS transistor 23 and an N-channel MOS transistor 24 are commonly connected between the input signal and the output signal to serve as a feedback resistor. Has been done.

For example, the transmission gate 2 described above.
When the feedback resistance value of No. 2 is designed to be 8 MΩ at the power supply voltage Vdd = 2.2 V, and the power supply voltage Vdd is used at 1.8 V to 3.6 V, the power supply voltage Vdd =
It was about 2 MΩ at 3.6 V and about 14 MΩ at the power supply voltage Vdd = 1.8 V, which was about 7 times the change.

[0004]

Recently, the demand for low-voltage operation of semiconductor integrated circuits has been strongly demanded due to the spread of portable equipment. In particular, in a MOS circuit, the threshold voltage Vt at which a transistor is turned on is generally constant at about 0.8 V, so that when the power supply voltage becomes low, the dependence of the characteristics of the transistor on the power supply voltage increases.

However, when the frequency divider or the like is driven by using the self-bias type amplifying circuit of FIG. 2, the feedback resistance value is reduced when the power supply voltage is increased, and as a result, the amplification degree is also reduced. It will not be possible to obtain sufficient output to drive a frequency divider or the like.

That is, in the self-bias type amplifier circuit in which the feedback resistor R is connected between the input and output of the inverter, the input voltage of the inverter is Vin and the output voltage is Vou.
When the feedback resistance R is small, the output voltage Vout is not amplified with respect to the input voltage Vin when the feedback resistance R is small, as shown in FIG.
ut cannot obtain a sufficient amplification degree.

Further, when the power supply voltage becomes lower, the feedback resistance value increases, and as a result, the resistance becomes weaker against the leak on the input side.
As shown in b-2, the degree of amplification is lowered, and an output sufficient to drive the frequency divider or the like cannot be obtained. As shown in FIG. 4- (b), when the feedback resistance R is large, the response of the inverter also becomes steep and a large amplification degree can be obtained, but the self-bias voltage Vin largely deviates with respect to the minute leak current on the input side. For example, the output voltage Vout is clipped, and the waveform of the output voltage Vout is distorted. Therefore, the feedback resistance of the self-bias type amplifier circuit is required to have little dependency on the power supply voltage. The present invention has been made in view of the above problems, and an object of the present invention is to provide a feedback resistor having little power supply voltage dependency.

[0008]

The present invention SUMMARY OF], the power supply and the inverter, in the amplifier circuit composed of a feedback resistor feedback path opposite conductivity type transistor each other formed by connecting the inverter, supplied from a power source A first and a second voltage control circuit for reducing the change of the output voltage with respect to the change of the voltage, wherein the first voltage control is applied to the gate of one conductivity type transistor of the reverse conductivity type transistors. The output voltage of the circuit is input, and the output voltage of the second voltage control circuit is input to the gate of the other conductivity type transistor , and the source of the first voltage control circuit is
On the ground side, a first transistor whose gate is connected to the power supply
And the drain and gate of the first transistor
Is connected between the gate and the gate, and one end of the gate is connected to the power supply.
Has a resistance element connected to the other side, and the other end of the resistance element
The output voltage is supplied from the connection path between the drain and
The source of the second voltage control circuit is
On the power supply side, the second transistor whose gate is connected to ground
The drain of the second transistor and the gate
And the gate is connected to the ground side together with the gate.
And a resistor element connected to the other end of the resistor element.
It said output voltage from a connection path between the drain and said Rukoto supplied.

[0009]

[0010]

Further, the inverter circuit outputs a third transistor whose source is connected to the power source side, a fourth transistor whose source is connected to the ground, and a common drain of the third and fourth transistors, It is characterized in that inverters having the common gates of the third and fourth transistors as inputs are cascaded in one or more stages.

According to the present invention, the feedback resistance value of the self-bias type amplifying circuit composed of the transmission gate circuit which changes depending on the gate-source voltage, and the gate voltage of the transmission gate circuit by the voltage control circuit, Control is performed to reduce the power supply voltage dependency.

[0013]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In a conventional self-bias type amplifier circuit,
It is provided with first and second voltage control circuits 3 and 4 that reduce the amount of change in the output voltage with respect to the change in the power supply voltage Vdd. Furthermore, the first voltage control circuit 3 has a resistor element 5 having one end connected to the power supply Vdd and a source on the ground side.
The drain has the other end of the resistance element, and the gate has the power supply Vdd.
And an N-channel enhancement MOS transistor 6 connected to the N-channel enhancement MOS transistor 6, and the drain of the N-channel enhancement MOS transistor is output.
The second voltage control circuit 4 has a resistance element 7 whose one end is connected to the ground side, a P-channel enhancement MOS whose source is connected to the power supply Vdd, whose drain is connected to the other end of the resistance element, and whose gate is connected to the ground. And a drain of the P-channel enhancement MOS transistor 8 as an output.

In FIG. 1, the MOS transistors 21 and 22 of the transmission gate 2 are not directly connected to the power supply voltage side or the ground side, but are provided with the first and second voltage control circuits 3 and 4. It is connected to the power supply side or the ground side via.

In the first voltage control circuit 3, the MOS
Since the gate of the transistor 6 is connected to the power supply voltage Vdd, the MOS transistor 6 has Vgs = Vds.
The current flows under the condition. Then, in the MOS transistor 6, a current Ip flows in the MOS transistor 6.
By changing the area of the MOS transistor 6,
It is possible to change the value of the current Ip at a certain power supply voltage Vdd. Therefore, in FIG. 1, for example, by reducing the area of the MOS transistor 6, the power supply voltage Vd
The change in the current Ip with respect to the change in d is set small.

Further, M included in the second voltage control circuit 4
The gate of the OS transistor 8 is grounded. Therefore, the current In flows through the MOS transistor 8 with respect to the power supply voltage Vdd. Like the MOS transistor 6,
For example, by reducing the area of the MOS transistor 8, the change in the current In with respect to the change in the power supply voltage Vdd is set small.

It should be noted that the MOS for changes in the power supply voltage Vdd
In order to reduce the change in the current flowing through the transistor,
Although the area of the MOS transistor is set, it can be achieved by adjusting the values of the resistors 5 and 7.

The output voltages of the first and second voltage control circuits 3 and 4 are applied to the gates of the MOS transistors 21 and 22, respectively. MOS transistors 21 and 22
A gate voltage having a small voltage change with respect to the power supply voltage Vdd is applied to the gate of the. Therefore, MOS
Gate-source voltage Vg of the transistors 21 and 22
s changes as shown by the solid line in FIG.

In FIG. 1, the input voltage V of the inverter 1
When Vdd that is at the “H” level is applied as in, the ON resistance of the MOS transistor 21 to which the output voltage of the first voltage control circuit 3 is applied becomes the feedback resistance value. Vdd =
In the case of 1.8V, the gate-source voltage Vgs of the MOS transistor 21 is about 1.6V as shown in FIG. Further, when Vdd = 3.6 V, the gate-source voltage Vg of the MOS transistor 21 as shown in FIG.
s will be about 2.2V.

Conventionally, that is, MOS transistors 21 and 2
When the power supply voltage is directly applied to 2 and grounded, the change of the power supply voltage Vdd, Vdd = 1.8V to 3.6V,
Gate-source voltage Vgs of the MOS transistor 21
Shows a change of 1.8V from 1.8 to 3.6V as shown in FIG.

On the other hand, in the present invention, the power supply voltage Vd
d = 1.8V-3.6V for changes of 1.6V-2.
There is a change of 0.6V up to 2V. Therefore, the gate-source voltage Vgs of the MOS transistor 21 of the transmission gate 2 in FIG. 1 can be reduced with respect to the change of the power supply voltage.

When Vss (0V) is applied as the input voltage Vin of the inverter 1, the ON resistance of the MOS transistor 22 to which the output voltage of the second voltage control circuit 4 is applied becomes the feedback resistance value. As in the case where the power supply voltage Vdd is applied as the input voltage Vin, the power supply voltage Vdd =
For a change of 1.8 to 3.6 V, MO as shown in FIG.
The change in the gate-source voltage Vgs of the S transistor 22 is a change of 0.6V from 1.6 to 2.2V.

Since the changes of the MOS transistors 21 and 22 of the transmission gate 2 are reduced with respect to the change of the power supply voltage Vdd, the resistance value of the transmission gate 2 becomes as shown in FIG. Power supply voltage V
dd = 3.6V, resistance value is about 4 MΩ, power supply voltage Vdd =
At 1.8 V, it becomes about 10 MΩ, which is a change of about 2.5 times. Conventionally, when the power supply voltage Vdd is between 1.8 V and 3.6 V, the change in resistance value is as much as seven times, so the change in resistance value of the transmission gate 2 can be greatly reduced.

Therefore, according to the present invention, an inverter circuit
In the self-bias type amplifier circuit configured by 1 and the transmission resistance gate circuit 2 for feedback resistance, it is possible to reduce the change of the resistance value of the transmission gate circuit 2 with respect to the power supply voltage.

Further, as shown in FIG. 3, even in the low voltage region of the power supply voltage Vdd, the change of the resistance value of the transmission gate 2 can be made gradual, so that the stable resistance value can be obtained. ing.

[0026]

According to the present invention, in a self-bias type amplifier circuit using a feedback resistance of a MOS device having a low operating voltage and a wide operating power supply voltage range, a feedback resistance value having a small power supply voltage dependency can be obtained. A stable amplification operation can be performed even in a wide power supply voltage range.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a characteristic diagram showing a relationship between a power supply voltage Vdd and a resistance value of a transmission gate.

FIG. 4 is a characteristic diagram showing a relationship between a value of a feedback resistance and an amplification factor of an amplifier circuit.

FIG. 5 is a characteristic diagram showing a relationship between a power supply voltage Vdd and a gate-source voltage of a MOS transistor.

[Explanation of symbols]

1 Inverter, 3 1st voltage control circuit, 4 2nd
Voltage control circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohiro Yamamoto 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) Reference JP-A-7-221549 (JP, A) JP 10-65459 (JP, A) JP-A-6-224648 (JP, A) JP-A-6-164240 (JP, A) Actually developed 59-56825 (JP, U) (58) Fields investigated (Int .Cl. ⁷ , DB name) H03F 1/30 H03F 1/34

Claims (2)

(57) [Claims] 1. An amplifier circuit comprising an inverter and a feedback resistor formed by connecting transistors of opposite conductivity type to a feedback path of the inverter, the amplifier circuit being supplied from a power source.
A first and a second voltage control circuit for reducing the change of the output voltage with respect to the change of the power supply voltage, and the first conductivity type transistor is provided to the gate of one conductivity type transistor of the reverse conductivity type transistors. Input the output voltage of the voltage control circuit,
A of entering the output voltage of the second voltage control circuit to the gate of the other conductivity type transistor, the first voltage control circuit includes a first source connected to the ground, and a gate to the power supply 1
The transistor and the drain and front of the first transistor
It is connected between the gate and one end together with the gate.
A resistor element connected to the power source side,
The output voltage from the connection path between the other end of the child and the drain
Is supplied to the second voltage control circuit, the second voltage control circuit is configured such that the source is connected to the power supply side and the gate is connected to ground.
Transistor and the drain and front of the second transistor
It is connected between the gate and one end together with the gate.
With a resistance element connected to the ground side,
The output voltage is supplied from the connection path between the other end and the drain.
Amplifier circuit, characterized in that the fed, Ru. 2. The source of the inverter circuit is the power source.
The third transistor connected to the source side and the source to ground
A connected fourth transistor and the third and fourth transistors
The common drain of the transistor is output, and the third and fourth
1 inverter with common gate of transistor as input
The increase according to claim 1, characterized in that they are connected in cascade in more than one step.
Width circuit.