JP3508333B2 - Constant voltage 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 constant voltage generating circuit composed of a differential amplifier circuit and an output stage circuit.

[0002]

2. Description of the Related Art Conventionally, a plurality of constant voltage circuits are required to obtain different constant voltage values. Figure 4
Described in. 4, 401 is a positive power supply, 402 is a negative power supply, 403 is a constant voltage circuit using an operational amplifier, 4
Reference numeral 04 is another constant voltage circuit using an operational amplifier, 405 is a load circuit driven by the constant voltage circuit 403, 406 is a load circuit driven by the constant voltage circuit 404, and 407.
Is a reference voltage for determining the output voltage of the constant voltage circuit 403, 4
Reference numeral 08 is a reference voltage that determines the output voltage of the constant voltage circuit 404. Since the output of the constant voltage circuit 403 is negatively fed back, the reference voltage 407 is impedance-converted to load the load circuit 4.
A constant voltage is supplied to 05. Similarly, since the constant voltage circuit 404 negatively feeds back the output, the reference voltage 408 is impedance-converted and the constant voltage is supplied to the load circuit 406. Figure 4
As described above, when different constant voltages are supplied to the load circuits 405 and 406, two constant voltage circuits 403 and 404 are required.

[0003]

In the case of the above-mentioned prior art, there are the following problems. Since the constant voltage circuit requires the same number of constant voltage values as desired and the circuit scale becomes large, there is a problem that the chip size is increased and the cost is increased in the case of the semiconductor integrated device.

[0004]

In order to solve the above-mentioned problems, the constant voltage circuit of the present invention comprises: a first transistor; a second transistor forming a differential pair with the first transistor; A third transistor forming a differential pair with the first transistor, and a first output stage circuit having a first output connected to the gate of the second transistor,
A second output stage circuit having a first capacitor connected between the first output and a first power supply; and a second output having a second output connected to the gate of the third transistor A constant voltage circuit including: the second output stage circuit having a second capacitor connected between the second output and the first power supply; A threshold value of the second transistor and a threshold value of the third transistor, which are simultaneously output by one output stage and the second output stage and which form the differential pair and receive a negative feedback input; Characterized by making each different.

(Means 2) In the constant voltage circuit of the present invention, the first transistor, the second transistor forming a differential pair with the first transistor, and the first transistor and the differential pair are provided. A third transistor and a first output stage circuit having a first output connected to the gate of the second transistor, the first output stage circuit being connected between the first output and a first power supply. A first output stage circuit having a first capacitor; and a second output stage circuit having a second output connected to the gate of the third transistor, the second output and the first output circuit In the constant voltage circuit including the second output stage circuit having a second capacitor connected between the power source of, the first output stage and the second output stage simultaneously output, The output values of the multiple output stage circuits are
It is characterized in that the plurality of output stage circuits are made different depending on the threshold values of the transistors.

[0006]

[0007]

[0008]

According to the present invention, even when it is desired to obtain a plurality of constant voltage values, a single differential amplifier circuit that constitutes a constant voltage circuit can be configured, so that a plurality of constant voltage can be generated without increasing the circuit scale. You can get it.

[0009]

EXAMPLES Examples of the present invention will be described below. FIG. 1 shows an embodiment of the present invention. FIG. 1 is a circuit diagram showing an example in which a constant voltage circuit is configured by MOS transistors, and is an example in which two output stage circuits are configured. In FIG. 1, 101 is a positive power source and 102 is a negative power source. 103 and 104 and 105
Is a constant current source. The differential amplifier circuit includes a constant current source 103,
P-type MOS transistors 106, 107 and 108 and N-type MOS transistors 109 and 110. P-type MOS
The transistor 106 and the P-type MOS transistor 107 and the P-type MOS transistor 106 and the P-type MOS transistor 108 are a differential pair transistor. A reference voltage 117 that determines the output voltage of the constant voltage circuit is input to the gate of the P-type MOS transistor 106. And
Two P-type transistors 107 and 108 are provided on the side of the P-type MOS transistor 106 that forms a differential operation pair. The N-type MOS transistors 109, 110 are active loads, and the differential pair P-type transistors 106, 107, 108
Is the drain load.

The first output stage circuit is a constant current source 104, a capacitor 111, and N-type MOS transistors 112 and 113.
Is. The capacitor 111 is a capacitor for phase correction,
The N-type MOS transistor 112 is an output stage transistor,
The N-type MOS transistor 113 is a switching transistor for operating the first output stage circuit. The gate of the N-type MOS transistor 112 in the output stage is a P-type MOS transistor 106 that constitutes a differential amplifier circuit.
The output of the N-type MOS transistor 112 in the output stage is negatively fed back to the gate of the P-type MOS transistor 107 of the differential amplifier circuit by the signal line 120.
If 13 is turned on, a constant voltage as the output of the first output stage circuit is obtained on the signal line 120.

Similarly, the second output stage circuit is a constant current source 10
5, capacitor 114, and N-type MOS transistor 11
5, 116. The capacitor 114 is a capacitor for phase compensation, the N-type MOS transistor 115 is an output stage transistor, and the N-type MOS transistor 116 is a switching transistor for operating the second output stage circuit. The gate of the N-type MOS transistor 115 in the output stage is a P-type MO transistor that constitutes a differential amplifier circuit, like the output-stage N-type MOS transistor 112 in the first output stage circuit.
It is controlled by the drain output of the S-transistor 106, and the output of the N-type MOS transistor 115 at the output stage is negatively fed back to the gate of the P-type MOS transistor 108 of the differential amplifier circuit by the signal line 121. When is turned on, a constant voltage as the output of the second output stage circuit is obtained on the signal line 121.

Here, the signal 118 is input to the gate of the switching transistor 113 of the first output stage circuit, and the signal 11 is input to the gate of the switching transistor 116 of the second output stage circuit by the inverter 119.
The inverted signal of 8 is input. If, for example, a pulse signal with a duty of 50% is applied to the signal 118, the switching transistors 113 and 116 are turned on alternately.
Since the output is repeatedly turned off, the output of the first output stage circuit and the output of the second output stage circuit perform a negative feedback operation in a time division manner, and at the same time, output each constant voltage to the signal 120 and the signal 121 in a time division manner. I can do things. Each constant voltage is signal 120 and signal 1
The signal is output in a time-division manner to 21. By inserting a capacitor between the ground power source and the signals 120 and 121, the constant voltage levels of the signals 120 and 121 can be smoothed. Further, capacitors are inserted between the ground power supply and the gate of the output stage transistor 112, and between the ground power supply and the gate of the output stage transistor 115, so that the output stage transistor 11
By holding the gate potential of 2,115, the signal 12
It is possible to stabilize the constant voltage level of 0 and the signal 121.
In the above description, the case where the number of output stage circuits is two has been described as an example. However, if the number of transistors on the negative feedback side of the differential transistors of the differential amplifier circuit is increased, the number of output stage circuits can be three or more. . Therefore, it is possible to output three or more constant voltage outputs.

Next, the means 2 will be described with reference to FIG. In the present invention, the P-type MO on the side receiving the negative feedback input in the differential pair transistor that constitutes the differential amplifier circuit of FIG.
The S transistors 107 and 108 have different threshold values. For example, it is assumed that the threshold of the P-type MOS transistor 106 and the threshold of the P-type MOS transistor 107 are the same, while the threshold of the P-type MOS transistor 108 is different. Then, the level of the signal 121, which is the second constant voltage output, with respect to the reference voltage 117 is P-type M
OS transistor 106 and P-type MOS transistor 10
Since the offset is applied by the difference between the threshold values of 8, a constant voltage value different from the level of the signal 120 which is the first constant voltage output can be obtained.

Next, the means 3 will be described with reference to FIG. FIG. 2 is a circuit diagram showing another embodiment of the present invention. In FIG. 2, the same components as those in FIG. 1 are given the same numbers for easy understanding. In the present invention, the N-type MOS transistor 201 is added to the first output stage circuit of FIG. The gate of the N-type MOS transistor 201 is an N-type M
Since it is connected to the drain of the OS transistor 201, a voltage substantially equivalent to the threshold value of the N-type MOS transistor 201 can be obtained between the signal 120 and the gate wiring of the P-type MOS transistor 107. Therefore, the first constant voltage output 120 can output a voltage different from the second constant voltage output 121 by substantially the threshold value of the N-type MOS transistor 201.

Next, the means 4 will be described with reference to FIG. FIG. 3 is a circuit diagram showing another embodiment of the present invention. Also in FIG. 3, the same components as those in FIG. 1 are denoted by the same numbers for easy understanding. In the present invention, the switching transistor 113 of the first output stage circuit of FIG.
The gate signal 303 and the gate signal 304 of the switching transistor 116 of the second output stage circuit are provided as independent signals, not as inverted signals. Then, the logical sum signal of the signals 303 and 304 is used as the NOR gate 302.
And is input to the gate of the P-type MOS transistor 301. The P-type MOS transistor 301 is a switching transistor that is turned on when operating the differential amplifier circuit section. The first output stage circuit performs the feedback operation when the signal 303 is high, and the second output stage circuit performs the feedback operation when the signal 304 is high.
3 or NOR gate 302 when signal 304 is high
As a result, the P-type MOS transistor 301 is turned on.
The differential amplifier circuit operates only when the output stage circuit performs the negative feedback operation.

[0016]

According to the present invention, even if it is desired to obtain a large number of constant voltage outputs, a single differential amplifier circuit constituting the constant voltage circuit can be realized, so that the circuit scale is not complicated and the cost is low. A semiconductor integrated circuit having a large number of constant voltage outputs can be provided.

Further, according to the present invention, since a large number of constant voltage output voltage values can be obtained only by changing the threshold values of the differential pair transistors forming the differential amplifier circuit, the operation reliability of the constant voltage circuit is improved. Since it is expensive and the circuit configuration is simple, a semiconductor integrated circuit having a large number of constant voltage outputs can be provided at low cost.

Further, according to the present invention, since a large number of constant voltage output voltage values can be obtained only by adding a transistor to the output stage circuit, similarly, the operation reliability of the constant voltage circuit is high and the circuit configuration is also high. Because of its simplicity, a semiconductor integrated circuit having a large number of constant voltage outputs can be provided at low cost.

Further, according to the present invention, the differential amplifier circuit and the output stage circuit which constitute the constant voltage circuit are time-division driven, and the current is consumed only at a necessary timing. Therefore, the constant voltage circuit which operates with low current consumption. Can be provided.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional technology example.

[Explanation of symbols]

101 Positive power source 102 Negative power supply 103 constant current source 104 constant current source 105 constant current source 106 P-type MOS transistor 107 P-type MOS transistor 108 P-type MOS transistor 109 N-type MOS transistor 110 N-type MOS transistor 111 capacitor 112 N-type MOS transistor 113 N-type MOS transistor 114 condenser 115 N-type MOS transistor 116 N-type MOS transistor 117 Reference potential 118 input signal 119 Inverter 120 First constant voltage output 121 Second constant voltage output 201 N-type MOS transistor 301 P-type MOS transistor 302 NOR gate 303 Input signal 304 input signal 401 Positive power source 402 Negative power supply 403 Operational amplifier 404 Operational amplifier 405 load circuit 406 load circuit 407 Reference potential 408 reference potential

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G05F 1/00-3/30 H03F 1/00-3/45 H03F 3/50-3/52 H03F 3/62-3 / 64 H03F 3/68-3/72

Claims (2)

(57) [Claims] 1. A first transistor, a second transistor forming a differential pair with the first transistor, a third transistor forming a differential pair with the first transistor, and a first output A first output stage circuit connected to the gate of the second transistor, the first output stage having a first capacitor connected between the first output and a first power supply. A second output stage circuit having a second output connected to the gate of the third transistor, the second output stage circuit being connected between the second output and the first power supply; In the constant voltage circuit including the second output stage circuit having a capacitor, the first output stage and the second output stage simultaneously output,
A constant voltage circuit, wherein the threshold value of the second transistor and the threshold value of the third transistor which configure the differential pair and receive a negative feedback input are different from each other. 2. A first transistor, a second transistor forming a differential pair with the first transistor, a third transistor forming a differential pair with the first transistor, and a first output A first output stage circuit connected to the gate of the second transistor, the first output stage having a first capacitor connected between the first output and a first power supply. A second output stage circuit having a second output connected to the gate of the third transistor, the second output stage circuit being connected between the second output and the first power supply; In the constant voltage circuit including the second output stage circuit having a capacitor, the first output stage and the second output stage simultaneously output,
A constant voltage circuit, wherein output values of the plurality of output stage circuits are different depending on threshold values of transistors forming the plurality of output stage circuits.