JPH0116051B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage divider circuit, and more particularly to a semiconductor device using complementary insulated gate field effect transistors.

Conventionally, in liquid crystal display circuits such as calculators, a static drive method using a plurality of power supply voltages has generally been used due to restrictions on the number of connection terminals between the drive circuit and the liquid crystal. Usually the resistance is as shown in Figure 1.
This method uses a voltage divider circuit in which R ₁ to _{R 3} are connected in series to obtain multiple voltage sources.While increasing the resistance reduces power consumption in this part, it uses a static drive method. Therefore, when the clock switches, the divided voltages _V1 and _V2 are affected by the capacitive coupling between the electrodes of the liquid crystal element, and the voltage level divided by the resistor cannot be kept constant. In order to keep this level constant, the voltage divider circuit must consume a certain amount of power, which limits the ability to reduce power consumption. Another conventional method is to divide the power supply using a high resistance element, take out only the potential, and connect a voltage follower to it. When the frequency of the static drive system is slow, the power consumption of the voltage follower can be reduced, and the overall effect is However, since the liquid crystal display element is equivalent to a capacitive element, when a dynamic operation is performed, the potential at both ends of the liquid crystal display element changes as the electrodes on the opposite side change. When the direction changes from this time constant current source to supplying current, the response speed of this circuit is determined by the size of this constant current source. In reality, the constant current source has become smaller in order to reduce the power consumption of the circuit, so the response speed is quite slow. Therefore, in order to compensate for this drawback, a large capacitance must be connected to the divided voltage output terminal. However, this method is impractical because it requires external terminals and capacitors, which goes against one of the advantages of integrated circuits, which is the need for fewer external components.

An object of the present invention is to provide a voltage dividing circuit with low power consumption and high accuracy.

The voltage divider circuit according to the present invention has a high resistance element connected in series between a first and a second power supply terminal, and divides a voltage between the voltages of the first and second power supply terminals. It has a resistor voltage divider circuit that outputs, first and second input terminals, and an output terminal, and when the potential of the first input terminal changes in the direction of the potential of the second power supply terminal, the output terminal When the potential of the output terminal changes in the direction of the potential of the first power supply terminal and the potential of the second input terminal changes in the direction of the potential of the second power supply terminal, the potential of the output terminal changes in the direction of the potential of the first power supply terminal. a differential amplifier circuit that changes in the direction of the potential of a second power supply terminal; a current source that is connected between the first power supply terminal and the voltage output terminal and whose current amount increases in response to a control signal; an electric field connected between the voltage output terminal and the second power supply terminal and having a conductivity type such that the amount of current increases when the potential of the gate changes in the direction of the potential of the first power supply terminal; an effect transistor, means for connecting the output terminal of the differential amplifier to the gate of the field effect transistor, means for applying the divided voltage to a first input terminal of the differential amplifier, and the differential amplifier circuit. and means for connecting a second input terminal of the voltage output terminal to the voltage division output terminal, and increasing the driving capability of the voltage output terminal in synchronization with the control signal.

According to the present invention, in a voltage divider circuit including a differential amplifier circuit using complementary field effect transistors, the potential of a power supply is divided using a high resistance element, and this is used as a reference power supply to one input terminal of the differential amplifier. The output of the differential amplifier path is input to an inverting amplifier with a field effect transistor of one conductivity type as an input transistor and a field effect transistor of the other conductivity type as a constant current source, and an internal circuit connected in parallel to the constant current source. A voltage dividing circuit is obtained in which a current source controlled by a control signal is provided and the output of this inverting amplifier is supplied to the other input terminal of the differential amplifier.

An embodiment of the present invention will be shown with reference to FIG. The potential of the power supply -V _D is divided by high resistances R ₂₁ , R ₂₂ , and R ₂₃ . Using these divided voltages V ₁ and V ₂ as a reference, Hiqh
The terminal _V1 that outputs the side level is the nch transistor _M2
The voltage V ₂ is output as V ₁ ′, V ₂ ′ through the voltage follower with a differential amplifier that uses the Pch transistor M ₁₁ as an input. This is because the operating range of the voltage follower is between the threshold value of the transistor used for input and the power supply voltage, so in a low power consumption system, 1/3 |V _D | is the threshold value of the transistor used for this input. This combination was selected because it is possible that the value is lower. If there is sufficient margin in the operating range of this voltage follower, such as when the power supply voltage is high, combinations other than this can be used. The output buffer section uses a combination of drive transistors M ₈ , M ₁₆ and constant current source transistors M ₉ , M ₁₅ , but in this case, another current source transistor M ₁₉ , in parallel with the constant current source is used. M ₂₀ is connected and the current source transistors M ₁₉ and M ₂₀ are controlled by control pulses φ ₁ and φ ₂ having mutually opposite phases. With this variable current source, control pulses φ ₁ and φ ₂ are input at timings when the driving force is insufficient with only the constant current source to compensate for the shortage. Therefore, according to this method, a stable intermediate potential can be obtained without connecting any external components. In the above example, the variable current sources were configured by two transistors M ₇ and M ₁₉ and M ₁₅ and M ₂₀ , respectively, but only one transistor M ₇ and M ₁₅ were used, and the gate of this one transistor was set to A. The amount of current flowing through the transistor may be controlled by switching from the bias potential at point or point B to ground (in the case of _M7 ) and -V _D (in the case of _M15 ) using a switch. Also, bias resistors R ₁₄ and R ₁₅ are made variable. For example, resistance
Other resistors are connected in parallel to R ₁₄ and R ₁₅ through switches, and the switches are turned on to reduce the effective resistance and one transistor M ₇ ,
A method of increasing the current amount of _M15 may also be used.

As described in detail above, according to the present invention, by configuring a voltage source using active elements, a voltage dividing circuit with lower power consumption and higher performance than conventional circuits can be realized.

In the present invention, the output buffer on the side of divided voltage _V1 is Pch
Input to transistor _M8 , nch transistor _M7 is used as a constant current source, but transistor _M7
The transistor _M8 may be used as a constant current source. The same thing can be said about the divided voltage _V2 side. Furthermore, by configuring the output buffer in two stages, the driving ability is improved. Furthermore, the transistor M ₆ ,
2 consisting of R ₁₄ and M ₁₄ resistor R ₁₅
As shown in FIG. 3, the two constant voltage circuits can be configured to include nch transistors M ₆ and M ₁₄ and a resistor R ₁₆ , thereby eliminating one resistor. Output end V ₁ ,
By connecting a capacitor to _V2 , it is also possible to absorb the level change when the control pulse is input. Furthermore, if there is high frequency noise in the power supply, a capacitor may be connected in parallel to the high voltage dividing resistor.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a conventional voltage dividing circuit, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Fig. 3 is a diagram showing a conventional voltage dividing circuit.
It is a figure which shows another example of the constant voltage circuit in the Example of a figure. R ₁ , R ₂ , R ₃ , R ₁₁ , R ₁₂ , R ₁₃ ... Resistance element,
R ₁₄ , R ₁₅ , R ₁₆ ...bias resistance of constant voltage circuit,
_M1 , _M2 , _M3 , _M6 , _M7 , _M9 , _M10 , _M16 ,
_M18 , _M19 ...nch transistor, _M4 , _M5 , _M8 ,
_M11 , _M12 , _M13 , _M14 , _M15 , _M17 , _M20 ...
Pch transistor, C ₁ , C ₂ , C ₃ , C ₄ , C ₅ ...capacitance.

Claims (1)

[Claims] 1 A resistive voltage divider circuit having a high resistance element connected in series between a first and a second power supply terminal, and outputting a divided voltage having a value between the voltages of the first and second power supply terminals. , has first and second input terminals and an output terminal, and when the potential of the first input terminal changes in the direction of the potential of the second power supply terminal, the potential of the output terminal changes to the potential of the first power supply terminal. The potential of the terminal changes in the direction of the second
a differential amplifier circuit in which the potential of the output terminal changes in the direction of the potential of the second power supply terminal when the potential of the input terminal of the first power supply terminal changes in the direction of the potential of the second power supply terminal; a current source connected between the power supply terminal and the voltage output terminal and whose current amount increases in response to a control signal; a field effect transistor having a conductivity type such that the amount of current increases as the voltage changes in the direction of the potential of the first power supply terminal; and an output terminal of the differential amplifier is connected to the gate of the field effect transistor. means for applying the divided voltage to a first input terminal of the differential amplifier; and means for connecting a second input terminal of the differential amplifier circuit to the divided voltage output terminal; A voltage dividing circuit characterized in that the driving capability of the voltage output terminal is increased in synchronization with the control signal.