JP3422706B2 - Startup circuit of reference voltage generator - Google Patents

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 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. It is a thing.

[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, particularly analog circuits, in order to realize stable characteristics. Among them, it is known that the feedback-controlled bandgap reference voltage generating 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 bandgap reference voltage generating circuit is
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 indicating the abnormal operating point is provided 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 occur immediately after the power is turned 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, the current mirror circuit 110 is shown.
And a current source composed of an NchMOS transistor 113 that determines the current of the current mirror circuit 110, and a PchMOS for the current value determined by the NchMOS transistor 113.
A constant current proportional to the transistor size ratio between the transistor 112 and the PchMOS transistor 111 is supplied to the first voltage generating circuit 210 and the second voltage generating circuit 220.

The first voltage generating circuit 210 comprises a resistance element 211, one end of which is connected to a reference voltage generating terminal 230, and a diode element 213, which is interposed between the other end of the resistance element 211 and GND. The connecting portion between the element 211 and the diode element 213 is used as the output terminal 214. The second voltage generation circuit 220 has 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 the resistance element 222.
Element 213 interposed between the other end of the and GND
The diode element 223 has an element size n times larger than the above, and the connection point between the resistance elements 221 and 222 is used as the output terminal 224.

Reference numeral 330 denotes a differential amplifier circuit, which is PchM
A constant current source 331 formed by an OS transistor and PchM that is supplied with current from the constant current source 331 and amplifies a differential input signal
It is provided with OS transistors 332 and 333, and a current mirror circuit composed of NchMOS transistors 334 and 335 which receives an amplified differential signal from the PchMOS transistor and extracts 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, and 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 PchMOS transistor constant current source 341 and an NchMOS which receives a current from the constant current source 341 and inverts and amplifies a signal from a gate input.
It is composed of a transistor 342. The inverting amplifier circuit 340 receives the signal from the differential amplifier circuit 330 and outputs the inverted amplifier signal to the 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 PchMOS transistor current source, which shares 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 to form a current mirror circuit. Each current source is configured so that 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 flows based on the current determined by the resistance element 241 of the load circuit 240.

A start-up circuit 400 is composed of an inverter circuit 370 and a control circuit 420. The inverter circuit 370 includes a PchMOS transistor 371 and an NchMOS transistor 372, receives the reference voltage generation terminal 230 as an input, and an output 373 is connected to an input of the control circuit 420. The control circuit 420 includes an inverter circuit 422 that inverts the control input signal and a PchMOS switch 421 whose output is connected to the gate input.
It is connected to the gate input of the 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 represents the voltage Vout of the reference voltage generation terminal 230, and the vertical axis represents the output 21 of the first and second voltage generation circuits.
The voltages V1 and V2 of 4, 224 are shown. When the potential of the reference voltage generation terminal 230 is raised from 0V, 0.7V
The on-resistance of the diode element is large up to the vicinity and is in a so-called off state.
Both 0 and 220 output substantially the same voltage as the reference voltage generation terminal 230. When the voltage Vout of the reference voltage output exceeds 0.7V, 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 approximately 0.7 V. Second voltage generation circuit 220
Since the diode element 223 is as large as n times as large as the diode element 213, the current starts to flow at a reference voltage output smaller than that of the diode element 213 of the first voltage generating circuit 210, and a current starts to flow. The output voltage Q2 applied to the resistance elements 221 and 222 is divided according to the resistance values of the two resistance elements 221, 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 generation circuits 2 with a reference voltage output of 7 V or more
Each output of 10 and 220 has a cross point P.

Differential amplifier circuit 330 and inverting amplifier circuit 340
Together operate as an operational amplifier circuit. The output of this operational amplifier circuit is the first and second voltage generation circuits 210, 2
20 is configured to control the NchMOS transistor 113 that determines the current of the first current source 111, and in general, the operational amplifier circuit has a large gain and the difference from the first and second voltage generation circuits 210 and 220. The dynamic inputs are feedback-controlled so that they are almost equal. When the output of the first voltage generating circuit 210 is lower than the output of the second voltage generating circuit 220, a large amount of the current from the constant current source 331 flows to the PchMOS transistor 333 side and the PchMOS transistor 332 side operates in the decreasing direction. I try to transfer points. However, since the current mirror circuit composed of NchMOS transistors 334 and 335 tries to flow the same current, PchM
The source-drain voltage of the OS transistors 332 and 333 is changed to maintain balance, and 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 rises, and the potential level of the inverting amplifier circuit output 343 lowers. As a result, the current of the NchMOS transistor 113 becomes smaller, and the operating point shifts in the direction of decreasing the current of the current mirror circuit 110. This lowers the potential level of the reference voltage output Vout. In the graph of FIG. 3, it is shown 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 generating circuit is lower than the output of the second voltage generating circuit) to the cross point P. On the other hand, when the output of the first voltage generating circuit 210 is higher than the output of the second voltage generating circuit 220, the operation is reversed, and the state on the left side of the cross point P on the graph of FIG.
The state changes to. Therefore, the cross point P in 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 generating 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 is
It is known that a reference voltage having a small temperature dependence can be obtained by selecting the resistance elements of the first and second voltage generating circuits 210 and 220 to have appropriate values.

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 except the cross point P where the reference voltage output is small, and this slight potential difference balances with the offset voltage of the operational amplifier circuit. There is a point, that is, an abnormal operation point. In this case, a normal reference voltage cannot be obtained.

In order to avoid entering such an operating point, the conventional reference voltage generating circuit is provided with the startup circuit 400 as shown in FIG.

The inverter circuit using the reference voltage output as an input signal outputs the H level when the reference voltage is low. When the inverter circuit output 373 becomes H level, the control circuit 4
The inverter circuit 422 in 20 is inverted, and the PchMOS transistor switch 421 receives the L level signal at the gate input and is turned on to raise the control output to the H level. The control circuit output is connected to the NchMOS transistor 113,
By 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 generator is
The point where the outputs of the first and second voltage generating circuits are at the same potential where the reference voltage output is small shifts to a higher reference voltage output.

When the reference voltage shifts to a high 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. After that, the reference voltage generating circuit shifts to a stable point and starts 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. When the switching level is higher than the reference voltage value for normal operation, the control circuit 420 tries to raise the reference voltage to a high level even if the stable point is exceeded, resulting in a reference voltage different from the designed 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 design is designed to shorten the development period by reusing the designed circuit blocks. Under such circumstances, a circuit that can stably operate in a wide power supply voltage range is required. The conventional start-up circuit uses an inverter circuit having a switching level that depends on the power supply voltage for a reference voltage that does not depend on the power supply voltage, and thus it is difficult to support a wide voltage range.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a start-up circuit of a reference voltage generating circuit capable of stably shifting from an abnormal operation point to a normal operation stable point even in a wide power supply voltage range. I am trying.

[0022]

In order to solve the above-mentioned problems, the start-up circuit of the reference voltage generating circuit of the present invention has both outputs of the first and second voltage generating circuits consisting of a resistance 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, The control circuit that operates according to the output signal of the comparator circuit increases the supply current to the reference voltage generation terminal, thereby shifting from the abnormal operating point to the normal stable operating point, and the output of the third voltage generating circuit has a diode. It is configured to use the ON voltage of.

A start-up circuit of a reference voltage generating circuit according to claim 1 has a reference voltage generating terminal, and a first resistance element having one end connected to the reference voltage generating terminal, and the first resistance element.
A first diode element in which an anode is connected to the other end of the resistance element and a cathode is connected to a low voltage source, and a connection point between the first resistance element and the first diode element is a first internal portion. A second resistance element having a first voltage generation circuit, which is a point, and a reference voltage generation terminal same as the first voltage generation circuit, and one end of which is connected to the reference voltage generation terminal, and the second resistance element A third resistance element having one end connected to the other end of the third 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 at the first internal point and the second internal point have the same potential. Feedback control of the current supplied to the reference voltage generation terminal so that a constant voltage is generated and the voltage at the first internal point is A start-up circuit of a reference voltage generation circuit having a normal operating point where a value and a voltage value of the second internal point match and an operating point other than the normal operating point, and having a third internal point, A third voltage generation circuit having a configuration having a diode element interposed between the third internal point and the low voltage source, and two input terminals, and two input terminals being the third A comparator circuit connected to the third internal point of the voltage generating circuit and the reference voltage generating terminals of the first and second voltage generating circuits to compare the potential levels of both 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. The control circuit is provided with a control circuit that shifts the reference voltage output from a stable point different from a normal operation to a normal operation point by controlling, has a third internal point, and has a third internal point.
Of the diode element installed between the internal point and the low voltage source
Characteristics, first diode element and second diode
The elements have the same characteristics.

According to the start-up circuit of the reference voltage generating circuit of claim 1, the potential level of the reference voltage output of the reference voltage generating terminal is compared with a preset potential level,
An abnormal operating point other than the normal operating stable point where the desired reference voltage is obtained when the power is turned on by raising the reference voltage output level by controlling the supply current that determines the potential level of the reference voltage when it is at the Low level. It is possible to reliably prevent falling into. Further, by using the comparator circuit for the determination of the potential level, the level determination depends only on the preset comparison target potential level, and the determination result of the comparator circuit does not depend on the power supply voltage, so that it operates stably in a wide power supply voltage range. It becomes possible. Further, since the preset potential level for comparison uses the ON voltage of the diode whose cathode is grounded to GND, it can be set to a potential level that is not affected by the power supply voltage. Furthermore, the diode elements of the two voltage generating circuits in the reference voltage generating circuit are
Since a diode element with the same characteristics as the child is used, the potential level between the abnormal operation point and the normal stable operation point can be set reliably, and the temperature characteristics of the on-voltage are the same, so there is no fluctuation in temperature. Also, stable operation is possible.

According to a second aspect of the present invention, in the start-up circuit of the reference voltage generating circuit according to the first aspect, the control circuit compares the reference voltage generating terminal with the third internal point by the comparator circuit, and the third internal point is detected. 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 normal operation to a normal operating point by increasing the supply current to the reference voltage generating terminal. Startup circuit.

According to the start-up circuit of the reference voltage generating circuit of the second aspect, the same effect as that of the first aspect can be 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, the two input terminals being the first internal point and the second internal point. Is performed by operational amplifier circuits respectively connected to the internal points of the.

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

According to a fourth aspect of the present invention, in the startup circuit of the reference voltage generating circuit according to the third aspect, the operational amplifier circuit has a differential amplifier circuit, and the differential amplifier circuit includes a constant current source,
A current is supplied from the constant current source, and both voltages at the first internal point and the second internal point of the first and second voltage generating circuits are input as a differential signal to amplify the differential signal. And a first and second current input terminal to which an amplified differential signal of the differential amplifier section is input, 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 the second current input terminal, and the second current input terminal serves as an output terminal of the differential amplifier circuit.

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

According to a fifth aspect of the present invention, in the startup circuit of the reference voltage generating circuit according to the fourth aspect, the operational amplifier circuit further includes an inverting amplifier circuit, and the inverting amplifier circuit has a constant current source and a differential amplifier circuit. The voltage at the output terminal of is inverted and amplified.

According to the start-up circuit of the reference voltage generating circuit of the fifth aspect, the same effect as in the fourth aspect can be 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, and the differential amplifier circuit has a constant current source and a current from the constant current source. Is supplied, the reference voltage of the reference voltage generating terminal and the third internal point are input as a differential signal, and a differential amplifier that amplifies the differential signal and an amplified differential signal of the differential amplifier Having a first and a second current input terminal to which is input, a current having a value proportional to the value of the signal input to the first current input terminal and having the same polarity as this signal is input to the second current input terminal. And a current mirror circuit that is pulled out from the second current input terminal, and the second current input terminal serves as an output terminal of the differential amplifier circuit.

According to the start-up circuit of the reference voltage generating circuit of claim 6, the same effect as that of claim 1 can be obtained.

According to a seventh aspect of the present invention, there is provided a start-up circuit for a reference voltage generating circuit according to the sixth aspect, wherein the comparator circuit further includes an inverting amplifier circuit, and the inverting amplifier circuit has a constant current source and a differential amplifier circuit. The voltage at the output terminal is inverted and amplified.

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

According to an eighth aspect of the present invention, in the start-up circuit of the reference voltage generating circuit according to the first aspect, the control circuit is a switch circuit provided between the constant voltage source and the control output terminal and has a control input terminal. It is used as an ON / OFF control terminal of the switch, and when the reference voltage output is lower than the potential of the third internal point as a result of comparing the reference voltage generation terminal and the third internal point by the comparator circuit, it is turned on by the output signal from the comparator circuit. However, at least the time to complete the transition operation to the normal operating point of the reference voltage generation circuit by reducing the supply current when reaching a constant voltage between the potential level of the control output terminal immediately before turning on and the constant voltage source potential level. A constant voltage is maintained in the range.

According to the start-up circuit of the reference voltage generating circuit of the invention described in claim 8, in addition to the same effect as that of claim 1, the reference voltage output is a potential at the normal operating point when shifting to the normal operating point. You can prevent it from becoming too big above the level. Therefore, it becomes unnecessary for the circuit side using this reference voltage to take measures against malfunction when an abnormal voltage larger than the 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, the constant current source of each of the differential amplifier circuit and the inverting amplifier circuit in the comparator circuit has a third voltage. The current mirror circuit is provided with two current mirror circuits each of which extracts a current having a value proportional to the current value flowing through the generating circuit and having the same polarity. Each current mirror circuit output serves as a constant current source output, and the third voltage generating circuit includes two current mirror circuits. It is shared as a load circuit of the current mirror circuit.

According to the start-up circuit of the reference voltage generating circuit of the invention described in claim 9, claim 6 or claim 7.
In addition to the effect similar to, the layout area and the DC current can be reduced by sharing the load circuit of the current mirror circuit necessary for forming the circuit and the circuit for generating the comparison target potential level.

The start-up circuit of the reference voltage generating circuit according to claim 10 is claim 4, claim 5, or claim 9.
The constant current sources of the differential amplifier circuit and the inverting amplifier circuit in the operational amplifier circuit are two current mirrors that extract currents of a value proportional to the current value of the third voltage generation circuit and having the same polarity. A circuit is provided, and each current mirror circuit output is used as a constant current source output, and the third voltage generating circuit is shared as a load circuit for the two current mirror circuits.

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

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

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

In FIG. 1, the current mirror circuit 110
And a current source 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 of the PchMOS transistor 112 and the PchMOS transistor 111 to the current value determined by the NchMOS transistor 113 The voltage is supplied to the first voltage generating circuit 210 and the second voltage generating circuit 220.

The first voltage generating circuit 210 comprises a resistance element 211, one end of which is connected to the reference voltage generation terminal 230, and a diode element 213, which is interposed between the other end of the resistance element 211 and GND. The connecting portion between the element 211 and the diode element 213 is used as the output terminal 214. The second voltage generation circuit 220 has 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 the resistance element 222.
Element 213 interposed between the other end of the and GND
A diode element 223 having an element size n times larger than that of the resistor element 221
224 .

Reference numeral 330 denotes a differential amplifier circuit, which is PchM
A constant current source 331 by an OS transistor, PchMOS transistors 332 and 333 that are supplied with current from this constant current source and amplify a differential input signal, and an amplified differential signal is input from this PchMOS transistor and a current corresponding to this input signal And a current mirror circuit made up of NchMOS transistors 334 and 335 for pulling out. 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, and 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 PchMOS transistor constant current source 341 and an NchMOS which receives a current from the constant current source 341 and inverts and amplifies a signal from a gate input.
It is composed of a transistor 342. The inverting amplifier circuit 340 receives the signal from the differential amplifier circuit 330 and outputs the inverted amplifier signal to the output terminal 343. This inverting amplifier output 34
3 is connected to the gate input of the NchMOS transistor 113 that determines the current of the current mirror circuit.

400 is a start-up circuit,
The voltage generating circuit 250, the comparator circuit 380, and the NchMOS transistor switch 411 which is a control circuit. The third voltage generating 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 connecting portion of 252 is used as an output terminal 253. The NchMOS transistor switch 411 is provided 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 is a constant current source 351 composed of PchMOS transistors.
And PchMOS transistors 352 and 353 which are supplied with a current from the constant current source 351 to amplify a differential input signal, and an amplified differential signal is input from these PchMOS transistors 352 and 353 and a current corresponding to this input signal is extracted. Nc
and a current mirror circuit including hMOS transistors 354 and 355. The input terminals of the differential amplifier circuit 350, that is, the gate inputs of the PchMOS transistors 352 and 353, which also serve as the input terminals 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, and output signals thereof. In response, the signal is differentially amplified and the amplified signal is output to the 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 consists of a transistor 362. The inverting amplifier circuit 360 receives the signal from the differential amplifier circuit 350 and outputs the inverting amplified signal to the output terminal 363. The inverting amplifier circuit output 363 which also serves as the output of the comparator circuit 380 is connected to the gate input of the NchMOS transistor switch 411.
Reference numeral 121 denotes a PchMOS transistor current source, which includes a constant current source 331 of the differential amplifier circuit 330, a constant current source 341 of the inverting amplifier circuit 340, and a constant current source 351 of the differential amplifier circuit 350 in the comparator circuit 380. A gate input node is shared with the constant current source 361 of the circuit 360 to form a current mirror circuit. Current mirror load circuit 2
40 is a resistance element 24 whose one end is connected to the current source 121.
It consists of 1. Each constant current source 331, 341, 351 and 3
Reference numeral 61 is a current source 1 based on the current flowing through the resistance element 241.
The current is proportional to the size of each constant current source transistor with respect to the transistor size of 21.

In such a circuit configuration, the current source composed of the current mirror circuit 110 and the NchMOS transistor 113, the 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 that of the conventional circuit of FIG. Here, the description of the operation of generating the reference voltage is omitted, and the operation of the start-up circuit 400 will be described.

This reference voltage generating circuit is similar to the conventional example,
Both the outputs 214, 2 of the first and second voltage generating circuits 210, 220 are supplied with current from the first current source shown above.
In addition to the normal operating point where 24 has the same potential, it has another operating point. This is a case where almost no current is supplied from the first current source, and at this time, the first and second voltage generation circuits 21
Both outputs 0 and 220 have a potential closer to the GND level than the normal operating point, and in this case also both outputs have substantially the same potential level. When the reference voltage generating terminal (reference voltage output) 230 reaches an operating point of a low potential level other than the normal operating point, the start-up circuit 400 operates as follows.

When the potential of the reference voltage output 230 is lower than that of the output 253 of the third voltage generating circuit 250, the current flowing in the PchMOS transistor 352 of the differential amplifier circuit 350 in the comparator circuit 380 increases in the direction of increasing the PchMOS transistor. The current flowing through 353 tries to shift the operating point in the decreasing direction. On the other hand, two NchMOS transistors 354 and 3
Since the current mirror circuit composed of 55 tries to pass the same current to the PchMOS transistors 352 and 353, the source-drain voltage of the PchMOS transistor 352 becomes small, and the source-drain voltage of the PchMOS transistor 353 becomes small.
The voltage between the drains increases and tries to maintain balance. As a result, the potential of the differential circuit output 356 is lowered to the Low level. The inverting amplifier circuit 360 outputs the differential amplifier circuit output 356.
The current flowing through the NchMOS transistor 362 tends to decrease in response to the change of the
Tries to maintain a constant current, the NchMOS transistor 3
The source-drain voltage of 62 increases and the output 36
3 shifts to High level.

By the operation of the comparator circuit 380, the NchMOS transistor switch 411 is turned on and a current is supplied to the first and second voltage generating 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 operation point shifts to the normal operation stable point where the desired reference voltage is obtained. When the reference voltage output 230 becomes higher than the output 253 of the third voltage generating circuit 250 during this transition, the comparator circuit 38
0 performs the reverse operation to the above operation and output 363 is Low
It becomes a level. As a result, NchMOS transistor switch 4
11 is turned off and the output of the control circuit is in a high impedance state to stop the operation of flowing a current into the first and second voltage generating circuits 210 and 220.

By the above-mentioned operation, it becomes 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 level of the two input signal levels, and the judgment level does not change depending on the supplied power supply voltage, so that a wide range of power supplies can be used. It becomes possible to avoid such an abnormal operating point in the voltage range.

The output 2 of the third voltage generating circuit 250
Since the voltage of 53 is determined by the ON voltage of the diode, it is possible to suppress the fluctuation of the output potential level due to the fluctuation of the power supply voltage. The configuration of the third voltage generation circuit 250 is
It is similar to the first and second voltage generating circuits 210 and 220 in that a diode element in which a cathode is connected to GND is used. Therefore, when the first and second voltage generating circuits are at the abnormal operating point, the first and second voltage generating circuits 210,
While the diode elements 213 and 223 in 220 are in the off state and the reference voltage output is at a low potential level, the diode element 25 in the third voltage generating circuit 250 is
2 is always on, and at this time, the third voltage generating circuit 2
The output 253 of 50 is always at a higher potential 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 operating point. As a result, the comparator circuit 380 reliably generates a signal for shifting from the abnormal operation point to the normal operation stable point.

On the other hand, the first and second voltage generating circuits 210,
When 220 is at the normal operating point, the diode elements 213, 2 in the first and second voltage generating circuits 210, 220
23 is in the 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 generating circuit 250 is always lower than the reference voltage output. . This indicates that in FIG. 3, the output potential V3 of the third voltage generation circuit 250 is always located on the left side of the normal operating point P. As a result, the comparator circuit 380, which sets the output of the third voltage generation circuit 250, which is determined only by the ON voltage of the diode, as the determination level, can reliably invert the output after the transition to the normal operating point P 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 generating circuits and the output of the third voltage generating circuit have similar temperature characteristics. Since it has, 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 generating circuit according to the second embodiment of the present invention.

In the reference voltage generating circuit of the second embodiment, the reference voltage generating circuit of the first embodiment of FIG.
Method for configuring third voltage generating circuit 250 and control circuit 410
The configuration of is different. That is, the third voltage generation circuit 250
Is 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 configured by the constant current source 351 of the differential amplifier circuit 350 in 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 generating circuit of FIG. 1 are deleted. Further, the control circuit 410
An NchMOS transistor switch 411 having a gate input whose one end is connected to a power supply terminal as a control input terminal and this NchM
It is composed of an NchMOS transistor 412 that is connected between the other end of the OS transistor switch 411 and the control output terminal and has its gate input connected to the other end of the NchMOS transistor switch 411 and is diode-connected. The control output terminal is the 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 parts having the same functions as those in FIG. 1 are designated by the same reference numerals and the detailed description thereof will be omitted.

In such a circuit configuration, the current source composed of the current mirror circuit 110 and the NchMOS transistor 113, the 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 that of the conventional circuit of FIG. Here, description of the operation of generating the reference voltage is omitted, and the start-up circuit 400
The operation related to is explained.

Similar to the first embodiment, this reference voltage generating circuit is supplied with current from the above-mentioned first current source to output both outputs of the first and second voltage generating circuits 210 and 220. It has another operating point other than the normal operating point where the potential is the same.
When the reference voltage output 230 reaches an operating point of a low potential level other than the normal operating point, the start-up circuit 4
00 operates as shown below.

When the potential of the reference voltage output 230 is lower than the output 253 of the third voltage generating circuit 250, the comparator circuit output 363 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. As a result, NchMOS transistor 1
The current flowing through 13 increases, and in proportion to this, the constant current source 11
The current of 1 increases. By this operation, the voltage generating circuit 2
The voltage across each element in 10, 220 increases and the reference voltage output 230 is raised to a high level. When the reference voltage output 230 rises, the operation point shifts to a normal operation stable point where a desired reference voltage is obtained.
When the reference voltage output 230 becomes a level higher than the output 253 of the third voltage generating circuit 250 during this transition, the comparator circuit 380 performs an operation opposite to the above operation and the output 363 becomes a low level. As a result, the control circuit 410
The NchMOS transistor switch 411 is turned off and the control circuit output 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 output terminal and the switch, the current is supplied when the switch is turned on and current is supplied to VDD -2Vt. The supply is stopped 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 excessively higher than the voltage obtained at the normal operating point.

FIG. 4A shows an operation waveform when the reference voltage output shifts from the abnormal operation point to the normal operation point P. In the case of the conventional circuit of FIG. 5, the control circuit 420 once raises the reference voltage output to a level close to the power supply voltage.
The reference voltage output becomes considerably larger than the normal operating point (cross point) P shown in FIG. 3, and the effect of returning to the cross point P by the feedback control is the differential amplifier circuit 3.
Works great at 30. As a result, cross point P
4B, the reference voltage output oscillates as shown in FIG. 4B. On the other hand, in the case of the circuit according to the second embodiment of the present invention in FIG. 2, the potential level at the normal operating point P does not become higher than the potential level, but rather approaches from the left side of the cross point P shown in FIG. It moves smoothly to the normal operating point without causing any movement.

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 generating circuit can be avoided. can do.

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

[0071]

According to the start-up circuit of the reference voltage generating circuit of claim 1, when the potential level of the reference voltage output of the reference voltage generating terminal is compared with a preset potential level and is at the Low level, By controlling the supply current that determines the potential level of the reference voltage, the reference voltage output level is raised, and it is possible to reliably prevent falling into an abnormal operation point other than the normal operation stable point where the desired reference voltage is obtained when the power is turned on. It becomes possible. Further, by using the comparator circuit for the determination of the potential level, the level determination depends only on the preset comparison target potential level, and the determination result of the comparator circuit does not depend on the power supply voltage, so that it operates stably in a wide power supply voltage range. It becomes possible. Further, since the preset potential level for comparison uses the ON voltage of the diode whose cathode is grounded to GND, it can be set to a potential level that is not affected by the power supply voltage. Furthermore, two of the voltage generating circuit of the reference voltage generator in circuit diode
Since a diode element with the same characteristics as the diode element is used, the potential level between the abnormal operation point and the normal stable operation point can be reliably set, and the temperature characteristics of the on-voltage are the same, so the temperature Stable operation is possible even with fluctuations.

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

According to the start-up circuit of the reference voltage generating circuit of the fifth aspect, the same effect as in the fourth aspect can be obtained.

According to the start-up circuit of the reference voltage generating circuit of claim 6, the same effect as that of claim 1 can be obtained.

According to the start-up circuit of the reference voltage generating circuit described in claim 7, the same effect as in claim 6 can be obtained.

According to the start-up circuit of the reference voltage generating circuit of the invention described in claim 8, in addition to the same effect as in claim 1, the reference voltage output is a potential at the normal operating point at the time of shifting to the normal operating point. You can prevent it from becoming too big above the level. Therefore, it becomes unnecessary for the circuit side using this reference voltage to take measures against malfunction when an abnormal voltage larger than the desired reference voltage is input.

According to the start-up circuit of the reference voltage generating circuit of the invention described in claim 9, claim 6 or claim 7.
In addition to the effect similar to, the layout area and the DC current can be reduced by sharing the load circuit of the current mirror circuit necessary for forming the circuit and the circuit for generating the comparison target potential level.

According to the start-up circuit of the reference voltage generating circuit of the invention described in claim 10, the same effect as in claim 4, claim 5, or claim 9 can be obtained.

[Brief description of 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 the first and second voltage generation circuits with respect to a reference voltage output potential.

4 is a diagram showing a waveform of a reference voltage output when shifting from an abnormal operating point to a normal operating point, (a) of FIG.
In the case of the above embodiment, (b) is the case of the conventional example of FIG.

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

[Explanation of symbols]

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 amplification circuit 331 Constant current source 332, 333 Differential amplification section PchMOS transistor 334, 335 Current mirror circuit section NchMOS transistor 336 Differential Amplifier circuit output 340 Inverting amplifier circuit 341 Constant current source 342 Inverting amplifier section 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 Electric power Generation circuit output 400 Startup 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 section NchMOS transistor 356 Differential amplification circuit output 360 Inversion amplification circuit 361 Constant current source 362 Inversion amplification section NchMOS transistor 363 Comparator circuit output (inversion amplification circuit output) 370 Inverter circuit 371 PchMOS transistor 372 NchMOS transistor 373 Inverter circuit Output Vout Reference voltage output V1 First voltage generator output potential V2 Second voltage generator output potential V3 Third voltage generator output potential

Continuation of front page (56) Reference JP-A-9-297626 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G05F 1 / 445,1 / 56 G05F 1 / 613,1 / 618 H03F 3/45

Claims (10)

(57) [Claims] 1. A first resistance element having a reference voltage generation terminal, one end of which is connected to the reference voltage generation terminal, and an anode connected to the other end of the first resistance element and a cathode of which is a low voltage source. A first diode element connected to the first diode element, and a connection point between the first resistance element and the first diode element is a first point.
A first voltage generating circuit which is an internal point of the second voltage generating circuit, a second voltage generating circuit having the same reference voltage generating terminal as that of the first voltage generating circuit, and 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 a low voltage source. And 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, the first internal point and the second internal point A constant voltage is generated by feedback-controlling the current supplied to the reference voltage generation terminal so that both voltages at the points have the same potential.
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 same and the voltage value of the second internal point match, and an operating point other than the normal operating point, A third structure having an internal point and having a diode element interposed between the third internal point and the low voltage source.
Voltage generating circuit and two input terminals, and the two input terminals are the third input terminals.
Comparator circuit connected to the third internal point of the voltage generating circuit and the reference voltage generating terminals of the first and second voltage generating circuits for comparing the potential levels of both voltages, and a control input terminal and a control circuit. An output terminal is provided, the control input terminal is connected to the output of the comparator circuit, and the signal from the control output terminal upon receiving the comparison result signal of the comparator circuit further controls the current supplied to the reference voltage generation terminal. By doing so, a control circuit is provided that shifts the reference voltage output from a stable point different from normal operation to the normal operation point, has the third internal point, and has the third internal point and the low power source.
Characteristics of the diode element provided between the pressure source,
The first diode element and the second diode
Start-up circuit of the reference voltage generation circuit with the same element characteristics . 2. The control circuit, when the reference voltage output is lower than the potential of the third internal point as a result of comparison between the reference voltage generating terminal and the third internal point by the comparator circuit, sends the reference voltage to the reference voltage generating terminal. The start-up circuit of the reference voltage generation 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 the supply current of the reference voltage generator. 3. The feedback control is performed by an operational amplifier circuit having two input terminals, the two input terminals being connected to a first internal point and a second internal point, respectively. Start-up circuit of the reference voltage generation circuit described. 4. The operational amplifier circuit has a differential amplifier circuit, and the differential amplifier circuit is provided with a constant current source, current supplied from the constant current source, and the first and second voltage generators. Both the voltage at the first internal point and the voltage at the second internal point of the circuit are input as a differential signal, and a differential amplifier that amplifies this differential signal and an amplified differential signal of this differential amplifier are input. A first and a second current input terminal, and a current having a value proportional to the value of the signal input to the first current input terminal and having the same polarity as the signal is output from the second current input terminal. The start-up circuit of the reference voltage generating circuit according to claim 3, further comprising a current mirror circuit for extracting the current mirror circuit, wherein the second current input terminal serves as 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, and the inverting amplifier circuit has a constant current source and inversely amplifies the voltage at the output terminal of the differential amplifier circuit. Circuit start-up circuit. 6. The comparator circuit has a differential amplifier circuit, and the differential amplifier circuit is provided with a constant current source, a current is supplied from the constant current source, and a reference voltage of the reference voltage generating terminal and the reference voltage. A third internal point is input as a differential signal, and a differential amplifier section that amplifies this differential signal and first and second current input terminals to which the amplified differential signal of this differential amplifier section is input are connected. A current mirror circuit for extracting a current having a value proportional to the value of the signal input to the first current input terminal and having the same polarity as the signal from the second current input terminal, The start-up circuit of the reference voltage generating circuit according to claim 1, wherein the current input terminal of is the output terminal of the differential amplifier circuit. 7. The comparator circuit further includes an inverting amplifier circuit, and the inverting amplifier circuit has a constant current source, and
7. The inverting amplification of the voltage of the output terminal of the differential amplifier circuit.
Start-up circuit of the reference voltage generation circuit described. 8. The control circuit is a switch circuit interposed between a constant voltage source and a control output terminal, wherein the control input terminal is a switch on / off control terminal, and a reference voltage generating terminal and a third voltage control terminal are provided. If the reference voltage output is lower than the potential of the third internal point as a result of comparison of the internal points by the comparator circuit, it is turned on by the output signal from the comparator circuit, and the potential level of the control output terminal immediately before turning on and the constant voltage source potential. The reference voltage according to claim 1, wherein the supply current is reduced when the voltage reaches a constant voltage intermediate between the level and the voltage, and the constant voltage is maintained at least in a time range in which the operation of shifting the reference voltage generating circuit to the normal operating point is completed. Start-up circuit of the generation circuit. 9. The constant current source of each of the differential amplifier circuit and the inverting amplifier circuit in the comparator circuit has two values which are proportional to the current value flowing in the third voltage generating circuit and which draw out currents of the same polarity. 8. A current mirror circuit is provided, wherein each of the current mirror circuit outputs serves as a constant current source output, and the third voltage generating circuit is shared as a load circuit of the two current mirror circuits. Start-up circuit of the reference voltage generation circuit described. 10. The constant current source of each of the differential amplifier circuit and the inverting amplifier circuit in the operational amplifier circuit has two pieces which draw a current having a value proportional to the current value flowing in the third voltage generating circuit and having the same polarity. 5. The current mirror circuit according to claim 4, wherein each of the current mirror circuit outputs serves as a constant current source output, and the third voltage generating circuit is shared as a load circuit for the two current mirror circuits. 5 or claim 9
Start-up circuit of the reference voltage generation circuit described.