JP2000181554A - Startup circuit for reference voltage generating circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a startup circuit capable of stably moving the operating point to normal point within a wide power supply voltage range in a reference voltage generating circuit. SOLUTION: When generating a reference voltage under the feedback control of both outputs from first and second voltage generating circuits 210 and 220 composed of resistors and diode elements while having a reference voltage generating terminal 230 through operational amplifier circuits 330 and 340, the outputs of a third voltage generating circuit 250 having a diode element 252 and the reference voltage generating terminal 230 are compared by a comparator circuit 380 and when the output level of the reference voltage generating terminal side is lower, a current to be supplied to the reference voltage generating terminal 230 is increased. Thus, a control circuit 411 for moving from an abnormal operating point to normal stable operating point is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start-up circuit for compensating for a stable operation of a reference voltage generating circuit which outputs a constant DC potential without being greatly affected by fluctuations in a supplied power supply voltage or temperature. Things.

[0002]

2. Description of the Related Art A reference voltage generating circuit for generating a constant DC potential is often used in various semiconductor circuit devices, especially analog circuits, for realizing stable characteristics. Among them, it is known that the feedback-controlled bandgap reference voltage generation circuit shown in FIG. 5 can suppress the fluctuation of the power supply voltage and the fluctuation of the output DC potential due to the temperature, and can obtain a good reference voltage.

This band gap reference voltage generating circuit
It has a normal operation stable point where a required DC potential is obtained by feedback control, and an abnormal operation point where a DC potential lower than the required potential is output. Therefore, in such a reference voltage generating circuit, a circuit for returning the operating point to a normal state when the output potential indicates an abnormal operating point is separately provided. This circuit is called a start-up circuit because it has a role of avoiding an abnormal operating point that tends to enter immediately after power-on.

The operation of the bandgap reference voltage generating circuit and the conventional start-up circuit will be described below with reference to FIG.

In FIG. 5, a current mirror circuit 110
A current source is composed of an NchMOS transistor 113 for determining the current of the current mirror circuit 110 and a PchMOS for a current value determined by the NchMOS transistor 113.
The configuration is such that a constant current proportional to the transistor size ratio between the transistor 112 and the PchMOS transistor 111 is supplied to the first voltage generation circuit 210 and the second voltage generation circuit 220.

The first voltage generation circuit 210 includes a resistance element 211 having one end connected to the reference voltage generation terminal 230, and a diode element 213 interposed between the other end of the resistance element 211 and GND. The connection between the element 211 and the diode element 213 is an output terminal 214. The second voltage generation circuit 220 includes a resistance element 221 having one end connected to the reference voltage generation terminal 230, a resistance element 222 having one end connected to the other end of the resistance element 211, and a resistance element 222.
Diode element 213 interposed between the other end of the
And a connection point between the resistance elements 221 and 222 is an output terminal 224.

Reference numeral 330 denotes a differential amplifier circuit, which is a PchM
A constant current source 331 including an OS transistor; and a PchM that is supplied with current from the constant current source 331 and amplifies a differential input signal.
OS transistors 332 and 333 and a current mirror circuit including Nch MOS transistors 334 and 335 that receive an amplified differential signal from the PchMOS transistor and extract a current corresponding to the input signal. The gate inputs of the PchMOS transistors 332 and 333 receive the output signals of the second and first voltage generation circuits 220 and 210, respectively, differentially amplify the signals, and output the amplified signals to the output terminal 336.

Reference numeral 340 denotes an inverting amplifier circuit, which is a constant current source 341 of a PchMOS transistor and an NchMOS which receives a current from the constant current source 341 and inverts and amplifies a signal from a gate input.
It comprises a transistor 342. Inverting amplifier circuit 340 receives the signal from differential amplifier circuit 330 and outputs an inverted amplified signal to output terminal 343. The output terminal 343 of the inverting amplifier circuit 340 is connected to the gate input of the NchMOS transistor 113 that determines the current of the current mirror circuit 110.

Reference numeral 121 denotes a current source of a PchMOS transistor, which forms a current mirror circuit by sharing a gate input node with the constant current source 331 of the differential amplifier circuit 330 and the constant current source 341 of the inverting amplifier circuit 340. Each current source is configured to flow a current proportional to the transistor size of the constant current sources 331 and 341 with respect to the transistor size of the current source 121, based on the current determined by the resistance element 241 of the load circuit 240.

Reference numeral 400 denotes a start-up circuit, which comprises an inverter circuit 370 and a control circuit 420. The inverter circuit 370 includes a PchMOS transistor 371 and an NchMOS transistor 372, has a reference voltage generation terminal 230 as an input, and an output 373 connected to an input of the control circuit 420. The control circuit 420 includes an inverter circuit 422 for inverting a control input signal and a PchMOS switch 421 whose output is connected to a gate input.
It is connected to the gate input of NchMOS transistor 113.

The operation of the first and second voltage generating circuits 210 and 220 having such a circuit configuration will be described with reference to FIG. The horizontal axis of FIG. 3 indicates the voltage Vout of the reference voltage generation terminal 230, and the vertical axis indicates the output 21 of the first and second voltage generation circuits.
4 and 224 are shown. When the potential of the reference voltage generating terminal 230 is increased from 0 V, 0.7 V
Up to the vicinity, the on resistance of the diode element is so large that the diode element is in an off state.
Both 0 and 220 output substantially the same voltage as the reference voltage generating terminal 230. When the voltage Vout of the reference voltage output exceeds 0.7 V, the diode element 213 turns on and a current flows,
The voltage of the reference voltage output of 0.7 V or more is applied to the resistance element 211, and the output Q1 of the first voltage generation circuit 210 becomes a constant voltage of about 0.7V. Second voltage generation circuit 220
Since the diode element 223 is n times as large as the diode element 213, the first voltage generation circuit 210 starts to turn on with a reference voltage output smaller than that of the diode element 213, and a current flows, and the voltage of the reference voltage output of 0.7 V or more is The output voltage Q2 is applied to the resistance elements 221 and 222, and the output voltage Q2 is divided according to the resistance values of the two resistance elements 221 and 222, and becomes an output voltage obtained by adding the voltage applied to the resistance element 222 and the ON voltage of the diode element 223. . As shown in FIG.
First and second voltage generating circuits 2 with a reference voltage output of 7 V or more
Each output of 10, 220 has a cross point P.

The differential amplifier circuit 330 and the inverting amplifier circuit 340
Together operate as an operational amplifier circuit. The output of this operational amplifier circuit is divided into first and second voltage generation circuits 210, 2
The NchMOS transistor 113 which determines the current of the first current source 111 is controlled. Generally, the operational amplifier circuit has a large gain and a difference from the first and second voltage generation circuits 210 and 220. Feedback control is performed so that the dynamic inputs become substantially equal. When the output of the first voltage generation circuit 210 is lower than the output of the second voltage generation circuit 220, a large amount of current from the constant current source 331 flows to the PchMOS transistor 333 and the PchMOS transistor 332 operates in a decreasing direction. Try to transfer points. However, the current mirror circuit composed of the NchMOS transistors 334 and 335 tries to pass the same current,
The balance is maintained by changing the source-drain voltage of the OS transistors 332 and 333. In this case, the voltage applied to the PchMOS transistor 333 is reduced. As a result,
The potential level of the differential amplifier circuit output 336 increases, and the potential level of the inverting amplifier circuit output 343 decreases. As a result, the current of the NchMOS transistor 113 decreases, and the operating point shifts in a direction to reduce the current of the current mirror circuit 110. This lowers the potential level of the reference voltage output Vout. The graph in FIG. 3 shows that the state changes from the state on the right side of the cross point P (the state where the output of the first voltage generation circuit is lower than the output of the second voltage generation circuit) toward the cross point P. On the other hand, when the output of the first voltage generation circuit 210 is higher than the output of the second voltage generation circuit 220, the operation is reversed, and the cross point P is changed from the state on the left side of the cross point P on the graph of FIG.
The state changes toward. Therefore, the cross point P on FIG. 3 is a stable operating point.

Even if the power supply voltage fluctuates, the cross point P is always maintained by the feedback control of the operational amplifier circuit, and the voltage at this time is the first and second voltage generation circuits 21.
Since it is determined only by the characteristics of the resistance elements 0 and 220 and the diode element, a reference voltage independent of the power supply voltage can be obtained.

Further, in this circuit, the fluctuation of the reference voltage with respect to the temperature also depends on the temperature characteristic of the diode on-voltage.
It is known that by selecting the resistance elements of the first and second voltage generation circuits 210 and 220 to an appropriate value, a reference voltage with small temperature dependence can be obtained.

On the other hand, as shown in FIG. 3, there is almost no potential difference between the outputs of the first and second voltage generating circuits where the reference voltage output is small other than at the cross point P, and this slight potential difference balances with the offset voltage of the operational amplifier circuit. There is a point, that is, an abnormal operating point. In this case, a normal reference voltage cannot be obtained.

In order to avoid such an operating point, a conventional reference voltage generating circuit is provided with a start-up circuit 400 as shown in FIG.

An inverter circuit that uses the reference voltage output as an input signal outputs an H level when the reference voltage is low. When the output of the inverter circuit 373 becomes H level, the control circuit 4
The inverter circuit 422 in the inverter 20 is inverted, and the PchMOS transistor switch 421 receives the L level signal at the gate input and turns on to raise the control output to the H level. The control circuit output is connected to the NchMOS transistor 113,
Due to this operation, the current of the current mirror circuit increases, and the potential level at each internal point of the first and second voltage generating circuits is raised. As a result, the operating point of the reference voltage generation circuit is
The transition from the point where the first and second voltage generation circuit outputs have the same potential where the reference voltage output is small to the high reference voltage output.

When the reference voltage shifts to a higher potential level, PchM
The OS transistor 421 is turned off, the output of the control circuit 420 becomes a high impedance state, and the effect of raising the reference voltage output stops. Thereafter, the reference voltage generation circuit shifts to a stable point and enters a normal operation.

[0019]

However, in the start-up circuit 400, attention must be paid to the setting of the switching level of the inverter circuit 370. If the switching level is higher than the reference voltage value for normal operation, the control circuit 420 attempts to raise the reference voltage to a higher level even if the stability point is exceeded, resulting in a reference voltage different from the design value.

The switching level also varies depending on the power supply voltage. In recent years, the power supply voltage has been scaled with the miniaturization in the semiconductor MOS process,
Due to the increase in the degree of integration, LSI designs are designed to reduce development time by reusing designed circuit blocks. Under such circumstances, a circuit that can operate stably in a wide power supply voltage range is desired. In a conventional start-up circuit, an inverter circuit having a switching level dependent on the power supply voltage is used for a reference voltage independent on the power supply voltage, so that it is difficult to correspond to a wide voltage range.

The present invention has been made in view of the above points, and an object of the present invention is to provide a start-up circuit of a reference voltage generation circuit which can stably shift from an abnormal operation point to a normal operation stable point even in a wide power supply voltage range. And

[0022]

In order to solve the above problems, a start-up circuit of a reference voltage generating circuit according to the present invention comprises a first and a second voltage generating circuit comprising a resistor element and a diode element. In a circuit that generates a reference voltage by feedback control by an operational amplifier circuit, an output from the third voltage generation circuit and an output from the reference voltage generation circuit are compared by a comparator circuit, and when the reference voltage output level is lower, A control circuit operated by a comparator circuit output signal to increase a supply current to a reference voltage generation terminal, thereby shifting from an abnormal operation point to a normal stable operation point, and a diode is connected to an output of the third voltage generation circuit. Is used.

According to a first aspect of the present invention, there is provided a start-up circuit for a reference voltage generation circuit, comprising a reference voltage generation terminal, a first resistance element having one end connected to the reference voltage generation terminal, and a first resistance element.
A first diode element having an anode connected to the other end of the resistance element and a cathode connected to the low voltage source, and a connection point between the first resistance element and the first diode element is connected to the first internal element. A first voltage generating circuit as a point, a second resistance element having the same reference voltage generation terminal as the first voltage generation circuit, one end of which is connected to the reference voltage generation terminal, and a second resistance element And a second diode element having an anode connected to the other end of the third resistance element and a cathode connected to the low-voltage source. A second voltage generating circuit in which a connection point between the second resistance element and the third resistance element is a second internal point, and both voltages of the first internal point and the second internal point are set to the same potential. A constant voltage is generated by feedback-controlling the supply current to the reference voltage generation terminal so that A start-up circuit of a reference voltage generating circuit having a normal operating point where the value matches the voltage value of the second internal point, and an operating point other than the normal operating point, comprising a third internal point; A third voltage generating circuit having a configuration having a diode element interposed between the third internal point and the low voltage source, and having two input terminals; A comparator circuit respectively connected to a third internal point of the voltage generation circuit and a reference voltage generation terminal of the first and second voltage generation circuits and comparing the potential levels of the two voltages;
It has a control input terminal and a control output terminal, the control input terminal is connected to the output of the comparator circuit, and the signal from the control output terminal receives the comparison result signal of the comparator circuit, and further supplies the current supplied to the reference voltage generation terminal. A control circuit is provided for shifting the reference voltage output from a stable point different from the normal operation to a normal operation point by controlling.

According to the start-up circuit of the reference voltage generating circuit, the potential level of the reference voltage output from the reference voltage generating terminal is compared with a preset potential level.
An abnormal operating point other than the normal operation stable point where the reference voltage output level is raised by controlling the supply current that determines the potential level of the reference voltage when the level is low, and the desired reference voltage can be obtained when the power is turned on. Can be reliably prevented. In addition, by using a comparator circuit for the determination of the potential level, the level determination depends only on a preset comparison target potential level, and since the determination result of the comparator circuit does not depend on the power supply voltage, it operates stably over a wide power supply voltage range. It becomes possible. In addition, since the preset comparison target potential level uses the on-voltage of the diode whose cathode is grounded to GND, the potential level can be further set to be not affected by the power supply voltage. Further, since the diode characteristics similar to those of the two voltage generation circuits in the reference voltage generation circuit are used, the potential level between the abnormal operation point and the normal stable operation point can be reliably set. Since they are the same, stable operation can be performed even when the temperature fluctuates.

According to a second aspect of the present invention, in the start-up circuit of the reference voltage generation circuit, the control circuit compares the reference voltage generation terminal with the third internal point by using a comparator circuit. 2. The reference voltage generating circuit according to claim 1, wherein when the reference voltage output is lower than the potential, the reference voltage output is shifted from a stable point different from a normal operation to a normal operating point by increasing a current supplied to the reference voltage generating terminal. Startup circuit.

According to the start-up circuit of the reference voltage generating circuit according to the second aspect, the same effect as that of the first aspect is obtained.

According to a third aspect of the present invention, in the start-up circuit of the reference voltage generating circuit according to the first aspect, the feedback control has two input terminals, and the two input terminals are the first internal point and the second internal terminal. Are performed by the operational amplifier circuits respectively connected to the internal points.

According to the start-up circuit of the reference voltage generation circuit according to the third aspect, the same effect as that of the first aspect is obtained.

According to a fourth aspect of the present invention, in the startup circuit of the reference voltage generating circuit, the operational amplifier circuit has a differential amplifier circuit, and the differential amplifier circuit has a constant current source;
A current is supplied from the constant current source, and both voltages at the first and second internal points of the first and second voltage generating circuits are input as a differential signal, and the differential signal is amplified. And a first and a second current input terminal to which the amplified differential signal of the differential amplifier is input, and which is proportional to the value of the signal input to the first current input terminal. A current mirror circuit for extracting a current having the same value and the same polarity as this signal from a second current input terminal, wherein the second current input terminal is an output terminal of the differential amplifier circuit.

According to the start-up circuit of the reference voltage generating circuit according to the fourth aspect, the same effect as that of the third aspect is obtained.

According to a fifth aspect of the present invention, in the start-up circuit of the reference voltage generating circuit, the operational amplifier circuit further includes an inverting amplifier circuit. The inverting amplifier circuit has a constant current source and a differential amplifier circuit. And inverts and amplifies the voltage of the output terminal.

According to the start-up circuit of the reference voltage generating circuit according to the fifth aspect, the same effect as that of the fourth aspect is obtained.

According to a sixth aspect of the present invention, in the start-up circuit of the reference voltage generating circuit according to the first aspect, the comparator circuit has a differential amplifier circuit. Is supplied, the reference voltage of the reference voltage generation terminal and the third internal point are input as a differential signal, and a differential amplifier for amplifying the differential signal; an amplified differential signal of the differential amplifier; And a second current input terminal having a value proportional to the value of a signal input to the first current input terminal and having the same polarity as the signal. And a second current input terminal serving as an output terminal of the differential amplifier circuit.

According to the start-up circuit of the reference voltage generating circuit according to the sixth aspect, the same effect as that of the first aspect is obtained.

According to a seventh aspect of the present invention, in the start-up circuit of the reference voltage generating circuit, the comparator circuit further includes an inverting amplifier circuit, the inverting amplifier circuit having a constant current source and a differential amplifier circuit. It inverts and amplifies the voltage of the output terminal.

According to the start-up circuit of the reference voltage generating circuit according to the seventh aspect, the same effect as that of the sixth aspect is obtained.

In a preferred embodiment, the control circuit is a switch circuit interposed between the constant voltage source and the control output terminal, the control input terminal being connected to the control input terminal. An on / off control terminal of the switch, which is turned on by an output signal from the comparator circuit when the reference voltage output terminal is lower than the potential of the third internal point as a result of comparison between the reference voltage generation terminal and the third internal point by the comparator circuit. And a time required to reduce the supply current when reaching a constant voltage intermediate between the potential level of the control output terminal and the potential level of the constant voltage source immediately before turning on to complete at least the shift operation of the reference voltage generating circuit to the normal operating point. In the range, a constant voltage is maintained.

According to the start-up circuit of the reference voltage generating circuit of the present invention, in addition to the same effects as those of the first aspect, when the reference voltage output shifts to the normal operating point, the reference voltage output is the potential at the normal operating point. It can be prevented that the level becomes too large. For this reason, it is not necessary for the circuit using the reference voltage to consider a countermeasure against a malfunction when an abnormal voltage larger than a desired reference voltage is input.

According to a ninth aspect of the present invention, in the start-up circuit of the reference voltage generating circuit according to the sixth or seventh aspect, each of the constant current sources of the differential amplifier circuit and the inverting amplifier circuit in the comparator circuit is connected to a third voltage source. Two current mirror circuits are provided for extracting currents of the same polarity with a value proportional to the value of the current flowing through the generation circuit. Each current mirror circuit output is used as a constant current source output, and the third voltage generation circuit includes two current mirror circuits. It is commonly used as a load circuit of a current mirror circuit.

According to the start-up circuit of the reference voltage generating circuit according to the ninth aspect of the present invention, the sixth or seventh aspect of the present invention provides
In addition to the same effects as described above, the layout area and the DC current can be reduced by sharing the load circuit of the current mirror circuit necessary for configuring the circuit and the circuit that generates the potential level to be compared.

The start-up circuit of the reference voltage generating circuit according to claim 10 is the fourth, fifth or ninth aspect of the present invention.
Wherein the constant current source of each of the differential amplifier circuit and the inverting amplifier circuit in the operational amplifier circuit has two current mirrors for extracting a current having a value proportional to the value of the current flowing through the third voltage generating circuit and having the same polarity. And a third voltage generating circuit is shared as a load circuit for two current mirror circuits.

According to the start-up circuit of the reference voltage generation circuit according to the tenth aspect, the same effects as those of the fourth, fifth, and ninth aspects are obtained.

[0043]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a reference voltage generation circuit according to a first embodiment of the present invention.

In FIG. 1, current mirror circuit 110
A current source is composed of an NchMOS transistor 113 that determines the current of the current mirror circuit, and a constant current proportional to the transistor size ratio between the PchMOS transistor 112 and the PchMOS transistor 111 with respect to the current value determined by the NchMOS transistor 113. The first voltage generation circuit 210 and the second voltage generation circuit 220 are supplied.

The first voltage generation circuit 210 includes a resistance element 211 having one end connected to the reference voltage generation terminal 230, and a diode element 213 interposed between the other end of the resistance element 211 and GND. The connection between the element 211 and the diode element 213 is an output terminal 214. The second voltage generation circuit 220 includes a resistance element 221 having one end connected to the reference voltage generation terminal 230, a resistance element 222 having one end connected to the other end of the resistance element 211, and a resistance element 222.
Diode element 213 interposed between the other end of the
And a connection point between the resistance elements 221 and 222 is an output terminal 214.

Reference numeral 330 denotes a differential amplifier circuit.
A constant current source 331 formed by an OS transistor; PchMOS transistors 332 and 333 supplied with current from the constant current source to amplify a differential input signal; and a current corresponding to the input signal when an amplified differential signal is input from the PchMOS transistor. And a current mirror circuit including NchMOS transistors 334 and 335 for extracting the current. The gate inputs of the PchMOS transistors 332 and 333 receive the output signals of the second and first voltage generation circuits 220 and 210, respectively, differentially amplify the signals, and output the amplified signals to the output terminal 336.

Numeral 340 denotes an inverting amplifier circuit, which is a constant current source 341 of a PchMOS transistor and an NchMOS which receives current from the constant current source 341 and inverts and amplifies a signal from a gate input.
It comprises a transistor 342. Inverting amplifier circuit 340 receives the signal from differential amplifier circuit 330 and outputs an inverted amplified signal to output terminal 343. This inverting amplifier circuit output 34
3 is connected to the gate input of the NchMOS transistor 113 that determines the current of the current mirror circuit.

Reference numeral 400 denotes a start-up circuit.
, A voltage generating circuit 250, a comparator circuit 380, and an NchMOS transistor switch 411 as a control circuit. The third voltage generation circuit 250 includes a resistance element 251 having one end connected to the current source 122 and a diode element 252 interposed between the other end of the resistance element 251 and GND. The connection portion of 252 is an output terminal 253. The NchMOS transistor switch 411 is interposed between the power supply terminal and the reference voltage generation terminal 230.

The comparator circuit 380 further comprises a differential amplifier circuit 350 and an inverting amplifier circuit 360. The differential amplifier circuit 350 includes a constant current source 351 using a PchMOS transistor.
PchMOS transistors 352 and 353 that are supplied with current from the constant current source 351 to amplify the differential input signal, and that the amplified differential signal is input from the PchMOS transistors 352 and 353 to extract a current corresponding to the input signal. Nc
and a current mirror circuit including hMOS transistors 354 and 355. Gate inputs of the PchMOS transistors 352 and 353, which are also inputs of the differential amplifier circuit 350, that is, inputs of the comparator circuit 380, are connected to the reference voltage generation terminal 230 and the output terminal 253 of the third voltage generation circuit 250, respectively. Then, the signal is differentially amplified, and an amplified signal is output to an output terminal 356. Reference numeral 360 denotes an inverting amplifier circuit, which is a PchMOS transistor constant current source 361 and an NchMOS that receives a current from the constant current source 361 and inverts and amplifies a signal from a gate input.
It comprises a transistor 362. Inverting amplifier circuit 360 receives the signal from differential amplifier circuit 350 and outputs an inverted amplified signal to output terminal 363. The output of the inverting amplifier circuit 363, which is also the output of the comparator circuit 380, is connected to the gate input of the NchMOS transistor switch 411.
Reference numeral 121 denotes a current source of a PchMOS transistor. The constant current source 331 of the differential amplifier circuit 330, the constant current source 341 of the inverting amplifier circuit 340, and the constant current source 351 of the differential amplifier circuit 350 in the comparator circuit 380. A constant current source 361 of the circuit 360 and a gate input node are shared to form a current mirror circuit. Current mirror load circuit 2
40 is a resistance element 24 having one end connected to the current source 121.
Consists of one. Each of the constant current sources 331, 341, 351 and 3
Reference numeral 61 denotes a current source 1 based on a current flowing through the resistance element 241.
A current proportional to the size of each of the constant current source transistors with respect to the transistor size of 21 is configured to flow.

In such a circuit configuration, a current source including the current mirror circuit 110 and the NchMOS transistor 113, the first and second voltage generation circuits 210 and 22
0, the operation of the reference voltage generation circuit including the differential amplifier circuit 330 and the inverting amplifier circuit 340 is the same as the operation of the conventional circuit of FIG. Here, the description of the operation of generating the reference voltage is omitted, and the operation related to the startup circuit 400 will be described.

This reference voltage generating circuit is similar to the prior art.
A current is supplied from the first current source shown above, and both outputs 214 and 2 of the first and second voltage generation circuits 210 and 220 are supplied.
24 has another operating point in addition to the normal operating point having the same potential. This is the case where almost no current is supplied from the first current source. At this time, the first and second voltage generation circuits 21
Both outputs 0 and 220 have a potential higher than the GND level from the normal operating point, and in this case also, both outputs have substantially the same potential level. When the reference voltage generation terminal (reference voltage output) 230 becomes an operating point of a low potential level other than such a normal operating point, the startup circuit 400 operates as described below.

When the potential of the reference voltage output 230 is lower than the output 253 of the third voltage generation circuit 250, the current flowing through the PchMOS transistor 352 of the differential amplifier circuit 350 in the comparator circuit 380 increases. The current flowing through 353 attempts to shift the operating point in a direction to decrease. On the other hand, two NchMOS transistors 354, 3
Since the current mirror circuit composed of 55 tries to make the same current flow through the PchMOS transistors 352 and 353, the voltage between the source and the drain of the PchMOS transistor 352 becomes small, and the source and the drain of the PchMOS transistor 353 are reduced.
The drain-to-drain voltage increases and attempts to maintain equilibrium. As a result, the potential of the differential circuit output 356 is lowered to a low level. The inverting amplifier circuit 360 has a differential amplifier circuit output 356.
The current flowing through the NchMOS transistor 362 tends to decrease in response to the change in the operating point.
Is an NchMOS transistor 3 in order to maintain a constant current.
62, the source-drain voltage increases, and the output 36
3 shifts to the High level.

The NchMOS transistor switch 411 is turned on by the operation of the comparator circuit 380, and a current flows into the first and second voltage generation circuits 210 and 220. By this operation, the voltage applied to each element in the voltage generation circuits 210 and 220 increases, and the reference voltage output 23
0 is raised to High level. Reference voltage output 23
When 0 rises, the operating point shifts to a normal operation stable point where a desired reference voltage can be obtained. When the reference voltage output 230 becomes higher than the output 253 of the third voltage generation circuit 250 during this transition, the comparator circuit 38
0 performs the opposite operation to the above, and output 363 is Low
Level. As a result, the NchMOS transistor switch 4
The reference numeral 11 turns off, the output of the control circuit becomes a high impedance state, and the operation of supplying current to the first and second voltage generation circuits 210 and 220 is stopped.

By the above-described operation, it is possible to avoid an abnormal operation that is likely to occur when the power is turned on and to shift to a normal operating point.

According to the first embodiment of the present invention, the output inversion of the comparator circuit 380 is determined by the magnitude of the two input signal levels, and the judgment level does not change according to the supplied power supply voltage. An operation for avoiding such an abnormal operating point can be performed in the voltage range.

The output 2 of the third voltage generating circuit 250
Since the voltage 53 is determined by the ON voltage of the diode, it is possible to suppress a change in the output potential level accompanying a change in the power supply voltage. The configuration of the third voltage generation circuit 250 is
This is similar to the first and second voltage generation circuits 210 and 220 in that a diode element having a cathode connected to GND is used. Therefore, when the first and second voltage generation circuits are at the abnormal operating point, the first and second voltage generation circuits 210,
Diode elements 213 and 223 in 220 are in the off state and the reference voltage output is at a low potential level, while diode elements 213 and 223 in third voltage generation circuit 250 have
2 is always on, and at this time, the third voltage generation circuit 2
The output 253 of 50 is always at a potential higher than the reference voltage output. This indicates that, in FIG. 3, the output potential V3 of the third voltage generation circuit 250 is constant regardless of the reference voltage output potential Vout, and is always located on the right side of the abnormal operation point. As a result, the comparator circuit 380 generates a signal for reliably shifting from the abnormal operation point to the normal operation stable point.

On the other hand, the first and second voltage generation circuits 210,
When 220 is at the normal operating point, the diode elements 213, 2 in the first and second voltage generation circuits 210, 220
Reference numeral 23 indicates an ON state, and the reference voltage output has a potential level obtained by adding the voltage applied to the resistance element to the ON voltage of the diode. At this time, the output 253 of the third voltage generation circuit 250 always has a potential lower than the reference voltage output. . This indicates that the output potential V3 of the third voltage generation circuit 250 is always located on the left side of the normal operating point P in FIG. As a result, after the shift to the normal operating point P, the comparator circuit 380 that makes the output of the third voltage generating circuit 250 determined only by the ON voltage of the diode the determination level can invert the output without fail and stop the start-up operation. .

Further, even when the on-voltage of the diode fluctuates due to temperature fluctuation, the reference voltage output from the first and second voltage generation circuits and the output of the third voltage generation circuit have similar temperature characteristics. Therefore, an operation margin for temperature fluctuation can be secured.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. FIG. 2 is a circuit diagram of a reference voltage generation circuit according to a second embodiment of the present invention.

The reference voltage generation circuit according to the second embodiment differs from the reference voltage generation circuit according to the first embodiment in FIG.
Configuration method of third voltage generation circuit 250 and control circuit 410
Is different. That is, the third voltage generation circuit 250
Are the constant current source 331 of the differential amplifier circuit 330, the constant current source 341 of the inverting amplifier circuit 340, and the comparator circuit 38
It is shared as a load circuit of a current mirror circuit composed of the constant current source 351 of the differential amplifier circuit 350 within 0 and the constant current source 361 of the inverting amplifier circuit 360. Instead, the current source 121 and its load circuit 240 of the reference voltage generation circuit of FIG. 1 are eliminated. Also, the control circuit 410
An Nch MOS transistor switch 411 having a gate input having one end connected to the power supply terminal and having a control input terminal;
An NchMOS transistor 412 is connected between the other end of the OS transistor switch 411 and the control output terminal and has a gate input connected to the other end of the NchMOS transistor switch 411 and diode-connected. The control output terminal is a gate of the NchMOS transistor 113. Connected to input.

The other structure is the same as that of the reference voltage generating circuit shown in FIG. 1, and the portions having the same functions as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In such a circuit configuration, a current source composed of a current mirror circuit 110 and an Nch MOS transistor 113, and first and second voltage generating circuits 210 and 22
0, the operation of the reference voltage generating circuit including the differential amplifier circuit 330 and the inverting amplifier circuit 340 is the same as the operation of the conventional circuit of FIG. Here, the description of the operation of generating the reference voltage is omitted, and the startup circuit 400
The operation relating to will be described.

In this reference voltage generating circuit, similarly to the first embodiment, current is supplied from the first current source shown above, and both outputs of the first and second voltage generating circuits 210 and 220 are output. It has another operating point in addition to the normal operating point having the same potential.
When the reference voltage output 230 becomes an operating point of a low potential level other than the normal operating point, the start-up circuit 4
00 operates as described below.

When the potential of the reference voltage output 230 is lower than the output 253 of the third voltage generating circuit 250, the output 363 of the comparator circuit shifts to the high level as in the first embodiment.

By the operation of the comparator circuit 380, the NchMOS switch 411 in the control circuit 410 is turned on, and the gate input of the NchMOS transistor 113 is raised to the high level via the diode-connected NchMOS transistor 412. Thereby, the NchMOS transistor 1
The current flowing through the constant current source 11 increases in proportion to this.
The current of 1 increases. By this operation, the voltage generation circuit 2
The voltage applied to each element within 10, 220 increases, and reference voltage output 230 is raised to a high level. When the reference voltage output 230 rises, the operating point shifts to a normal operation stable point where a desired reference voltage can be obtained.
When the reference voltage output 230 becomes higher than the output 253 of the third voltage generation circuit 250 during this transition, the comparator circuit 380 performs an operation reverse to the above-described operation, and the output 363 becomes the low level. As a result, the control circuit 410
The NchMOS transistor switch 411 is turned off, and the output of the control circuit becomes a high impedance state, and the operation of raising the gate input of the NchMOS transistor 113 to the high level is stopped.

The switch in the control circuit 410 has Nc
Since the hMOS transistor switch 411 is used and the diode-connected NchMOS transistor 412 is interposed between the switch and the output terminal, the switch is turned on, the current is supplied, and when the current reaches VDD-2Vt, the current is reduced. The supply stops and the output potential is clipped to this potential level. This operation suppresses a rapid decrease in the on-resistance of the NchMOS transistor 113, that is, a rapid increase in the current of the first current source. Therefore, it is possible to prevent the potential level of the reference voltage generation terminal 230 from becoming too high than the voltage obtained at the normal operating point.

FIG. 4A shows an operation waveform when the reference voltage output shifts from the abnormal operating point to the normal operating point P. In the case of the conventional circuit of FIG. 5, the reference voltage output is once raised to a level close to the power supply voltage by the control circuit 420.
The reference voltage output is considerably larger than the normal operating point (cross point) P shown in FIG.
Works great at 30. As a result, the cross point P
, And the operation is liable to fall into an operation in which the reference voltage output oscillates as shown in FIG. On the other hand, in the case of the circuit according to the second embodiment of the present invention shown in FIG. 2, the potential level does not become too large at the normal operating point P, but rather approaches the left side from the cross point P shown in FIG. Move to the normal operating point smoothly without any operation.

Since the circuit of the second embodiment does not generate an output voltage higher than the reference voltage during normal operation, adverse effects on the operation of the circuit using this reference voltage generation circuit are avoided. can do.

Further, in the second embodiment, the differential amplifier 350 and the inverting amplifier 3 in the comparator 380 are used.
The load circuit of the current mirror circuit constituting the constant current source 60 and the differential amplifier circuit 330 for performing feedback control and the load circuit of the current mirror circuit constituting the constant current source of the inverting amplifier circuit 340 are connected to the third voltage generating circuit 250. Therefore, the layout area and DC current can be reduced as compared with the case where a load circuit is separately provided.

[0071]

According to the start-up circuit of the reference voltage generation circuit according to the first aspect, when the potential level of the reference voltage output of the reference voltage generation terminal is compared with the preset potential level, the low level is obtained. By controlling the supply current that determines the potential level of the reference voltage, the reference voltage output level is raised to reliably prevent the power supply from falling into an abnormal operation point other than the normal operation stable point at which a desired reference voltage can be obtained when the power is turned on. It becomes possible. In addition, by using a comparator circuit for the determination of the potential level, the level determination depends only on a preset comparison target potential level, and since the determination result of the comparator circuit does not depend on the power supply voltage, it operates stably over a wide power supply voltage range. It becomes possible. In addition, since the preset comparison target potential level uses the on-voltage of the diode whose cathode is grounded to GND, the potential level can be further set to be not affected by the power supply voltage. Further, since the diode characteristics similar to those of the two voltage generation circuits in the reference voltage generation circuit are used, the potential level between the abnormal operation point and the normal stable operation point can be reliably set. Since they are the same, stable operation can be performed even when the temperature fluctuates.

According to the start-up circuit of the reference voltage generating circuit according to the second aspect, the same effect as that of the first aspect is obtained.

According to the start-up circuit of the reference voltage generating circuit according to the third aspect, the same effect as that of the first aspect can be obtained.

According to the start-up circuit of the reference voltage generating circuit according to the fourth aspect, the same effect as that of the third aspect is obtained.

According to the start-up circuit of the reference voltage generating circuit according to the fifth aspect, the same effect as that of the fourth aspect is obtained.

According to the start-up circuit of the reference voltage generating circuit according to the sixth aspect, the same effect as that of the first aspect can be obtained.

According to the start-up circuit of the reference voltage generating circuit according to the seventh aspect, the same effect as that of the sixth aspect is obtained.

According to the start-up circuit of the reference voltage generating circuit according to the eighth aspect of the present invention, in addition to the same effects as those of the first aspect, when the shift to the normal operating point occurs, the reference voltage output becomes the potential at the normal operating point. It can be prevented that the level becomes too large. For this reason, it is not necessary for the circuit using the reference voltage to consider a countermeasure against a malfunction when an abnormal voltage larger than a desired reference voltage is input.

According to the start-up circuit of the reference voltage generating circuit according to the ninth aspect, the sixth or seventh aspect of the present invention provides
In addition to the same effects as described above, the layout area and the DC current can be reduced by sharing the load circuit of the current mirror circuit necessary for configuring the circuit and the circuit that generates the potential level to be compared.

According to the start-up circuit of the reference voltage generating circuit according to the tenth aspect, the same effects as those of the fourth, fifth, and ninth aspects are obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a reference voltage generation circuit according to a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a reference voltage generation circuit according to a second embodiment of the present invention.

FIG. 3 is a graph showing output potentials of first and second voltage generation circuits with respect to a reference voltage output potential.

4A and 4B are diagrams showing a waveform of a reference voltage output when shifting from an abnormal operation point to a normal operation point, and FIG.
FIG. 5B shows the case of the conventional example shown in FIG.

FIG. 5 is an overall configuration diagram of a conventional reference voltage generation circuit.

[Explanation of symbols]

Reference Signs List 110 current mirror circuit 111 constant current source 112 PchMOS transistor (current source) 113 NchMOS transistor 210 first voltage generation circuit 220 second voltage generation circuit 211, 221, 222 resistance element 213, 223 diode element 214 first voltage generation Circuit output 224 Second voltage generation circuit output 230 Reference voltage generation terminal (reference voltage output) 330 Differential amplifier circuit 331 Constant current source 332, 333 Differential amplifier PchMOS transistor 334, 335 Current mirror circuit unit NchMOS transistor 336 Differential Amplifier circuit output 340 Inverting amplifier circuit 341 Constant current source 342 Inverting amplifier NchMOS transistor 343 Inverting amplifier circuit output 121 Current source 240 Load circuit 241 Resistance element 122 Current source 250 Third voltage generation circuit 251 Resistance element 252 Diode element 253 Third voltage generation circuit output 400 Start-up circuit 410 Control circuit 411 NchMOS transistor switch 412 Diode-connected NchMOS transistor 420 Control circuit 421 PchMOS transistor switch 422 Inverter circuit 380 Comparator circuit 350 Differential amplifier circuit 351 Constant current source 352, 353 Differential Amplifier PchMOS transistor 354, 355 Current mirror circuit NchMOS transistor 356 Differential amplifier output 360 Inverting amplifier 361 Constant current source 362 Inverting amplifier NchMOS transistor 363 Comparator circuit output (inverting amplifier circuit output) 370 Inverter circuit 371 PchMOS transistor 372 NchMOS transistor 373 Inverter circuit output Vout Reference voltage output V1 First voltage generation circuit output potential V2 Second voltage generation circuit output potential V3 3 of the voltage generating circuit output potential

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayoshi Kinoshita 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (Reference) 5H430 BB01 BB05 BB09 BB11 EE06 FF02 FF12 GG04 HH03 JJ07 KK01 5J066 AA03 AA43 AA58 CA04 FA02 FA10 FA17 HA10 HA19 HA25 HA39 KA02 KA09 KA11 MA13 MA20 ND09 ND24 TA01 TA02

Claims (10)

[Claims] A first resistance element having a reference voltage generation terminal, one end of which is connected to the reference voltage generation terminal; an anode connected to the other end of the first resistance element, and a cathode connected to a low voltage source. And a connection point between the first resistance element and the first diode element is a first diode element.
A first voltage generating circuit, which is an internal point of the first voltage generating circuit; a second resistive element having the same reference voltage generating terminal as the first voltage generating circuit, one end of which is connected to the reference voltage generating terminal; A third resistance element having one end connected to the other end of the second resistance element, and a second diode element having an anode connected to the other end of the third resistance element and a cathode connected to the low voltage source. A second voltage generating circuit, wherein a connection point between the second resistance element and the third resistance element is a second internal point, wherein the first internal point and the second internal point are provided. A constant voltage is generated by feedback-controlling a supply current to the reference voltage generation terminal so that both voltages at the point become the same potential, and the first voltage is generated.
A start-up circuit of a reference voltage generating circuit having a normal operating point at which the voltage value of the internal point of the second internal point matches the voltage value of the second internal point, and an operating point other than the normal operating point; A third element having an internal point and having a diode element interposed between the third internal point and the low voltage source;
, And two input terminals, wherein the two input terminals are the third input terminals.
A comparator circuit respectively connected to the third internal point of the voltage generation circuit and the reference voltage generation terminals of the first and second voltage generation circuits and comparing the potential levels of the two voltages; An output terminal, wherein the control input terminal is connected to an output of the comparator circuit, and a signal from a control output terminal receives a comparison result signal of the comparator circuit, and further controls a supply current to the reference voltage generation terminal. And a control circuit for shifting the reference voltage output from a stable point different from a normal operation to the normal operation point. 2. A control circuit, comprising: a comparator circuit for comparing a reference voltage generation terminal with a third internal point; when a reference voltage output is lower than a potential of the third internal point, the control circuit transmits the reference voltage to the reference voltage generation terminal; 2. The start-up circuit according to claim 1, wherein the reference voltage output is shifted from a stable point different from a normal operation to a normal operation point by increasing a supply current of the reference voltage. 3. The feedback control is performed by an operational amplifier circuit having two input terminals, the two input terminals being respectively connected to a first internal point and a second internal point. Startup circuit for the described reference voltage generator. 4. The operational amplifier circuit has a differential amplifier circuit. The differential amplifier circuit is supplied with a current from the constant current source and generates the first and second voltage. Both voltages at a first internal point and a second internal point of the circuit are input as differential signals, a differential amplifier for amplifying the differential signal, and an amplified differential signal of the differential amplifier are input. First and second current input terminals, and outputs a current having a value proportional to the value of a signal input to the first current input terminal and having the same polarity as the signal from the second current input terminal. 4. The start-up circuit according to claim 3, further comprising: a current mirror circuit to be pulled out, wherein the second current input terminal is an output terminal of the differential amplifier circuit. 5. The reference voltage generator according to claim 4, wherein the operational amplifier circuit further includes an inverting amplifier circuit, the inverting amplifier circuit having a constant current source, and inverting and amplifying the voltage of the output terminal of the differential amplifier circuit. Circuit startup circuit. 6. The comparator circuit has a differential amplifier circuit. The differential amplifier circuit receives a current from the constant current source, a reference voltage of the reference voltage generation terminal, A third internal point is input as a differential signal, a differential amplifier for amplifying the differential signal, and first and second current input terminals to which an amplified differential signal of the differential amplifier is input. A current mirror circuit having a value proportional to a value of a signal input to the first current input terminal and having the same polarity as that of the signal being drawn from the second current input terminal; 2. The start-up circuit for a reference voltage generating circuit according to claim 1, wherein the current input terminal of the reference voltage generating circuit serves as an output terminal of the differential amplifier circuit. 7. The comparator circuit further includes an inverting amplifier circuit, the inverting amplifier circuit having a constant current source,
7. The inverting amplification of the voltage of the output terminal of the differential amplifier circuit.
Startup circuit for the described reference voltage generator. 8. A control circuit, comprising: a switch circuit interposed between a constant voltage source and a control output terminal, wherein a control input terminal serves as a switch on / off control terminal, and a reference voltage generation terminal and a third When the reference voltage output is lower than the potential of the third internal point as a result of the comparison of the internal points by the comparator circuit, the reference voltage output is turned on by the output signal from the comparator circuit, and the potential level of the control output terminal and the potential of the constant voltage source immediately before being turned on. 2. The reference voltage according to claim 1, wherein the supply current is reduced when the voltage reaches a constant voltage between the level and the constant voltage, and the constant voltage is maintained at least in a time range in which the shift operation of the reference voltage generating circuit to the normal operating point is completed. Startup circuit of the generator circuit. 9. The constant current source of each of the differential amplifier circuit and the inverting amplifier circuit in the comparator circuit has a value proportional to the value of the current flowing through the third voltage generating circuit and two currents of the same polarity. 8. A circuit according to claim 6, further comprising a current mirror circuit, wherein each of said current mirror circuit outputs is a constant current source output, and said third voltage generating circuit is shared as a load circuit of said two current mirror circuits. Startup circuit for the described reference voltage generator. 10. A constant current source of each of a differential amplifier circuit and an inverting amplifier circuit in an operational amplifier circuit is a constant current source that extracts a current having a value proportional to a current value flowing through a third voltage generating circuit and having the same polarity. 5. The current mirror circuit according to claim 1, wherein each of said current mirror circuit outputs is a constant current source output, and said third voltage generating circuit is shared as a load circuit of said two current mirror circuits. 5 or claim 9
Startup circuit for the described reference voltage generator.