TWI803969B - Power-up circuit with temperature compensation - Google Patents

Abstract

A power-up circuit with temperature compensation including a first current source, a current amplifier and a temperature compensation circuit is disclosed. The first current source is coupled to a first system voltage, and configured to generate an internal operating current according to an internal operating voltage. The current amplifier is coupled to the first current source and the first system voltage, and configured to generate an amplified current and a reference voltage corresponding to the amplified current according to the internal operating voltage and a parameter, wherein the internal operating voltage and the reference voltage have positive temperature coefficients, and the internal operating current and the amplified current have negative temperature coefficients. The temperature compensation circuit is coupled to the current amplifier, and configured to generate an output voltage with temperature compensation according to the reference voltage.

Description

Power startup circuit with temperature compensation

The invention refers to a power starting circuit, especially a power starting circuit with temperature compensation.

The traditional power start-up circuit can be composed of multiple metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, hereinafter referred to as MOSFET), in which the resistance value of MOSFET has a negative temperature coefficient (Negative Temperature Coefficient, NTC) . When the operating temperature rises, the carrier concentration of the MOSFET will increase and the conductivity will increase; that is, the conductivity of the MOSFET will increase at high temperature, causing the resistance of the MOSFET to decrease, so the resistance of the MOSFET has a negative temperature coefficient. Therefore, the output voltage generated by the traditional power startup circuit also has a negative temperature coefficient. In practical applications, when the operating temperature rises, the resistance value and the threshold voltage (Threshold Voltage, Vth) of the MOSFET decrease, causing the operation of the traditional power startup circuit to change accordingly, thereby changing the magnitude of the output voltage. In some cases, since the output voltage generated by the power startup circuit varies with temperature, subsequent circuits will not operate normally.

Therefore, how to provide a power startup circuit with temperature compensation is one of the important issues in this field.

Therefore, an object of the present invention is to provide a power starting circuit with temperature compensation, which includes a first current source, a current amplifier and a temperature compensation circuit. The first current source is coupled to a first system voltage for generating an internal operating current according to an internal operating voltage. The current amplifier is coupled to the first current source and the first system voltage, and is used to generate an amplified current and a reference voltage corresponding to the amplified current according to the internal operating current and a parameter; wherein the internal operating voltage and The reference voltage has a positive temperature coefficient, and the internal operating current and the amplified current have negative temperature coefficients. The temperature compensation circuit is coupled to the current amplifier and is used for generating an output voltage with temperature compensation according to the reference voltage.

Compared with the prior art, the power starting circuit with temperature compensation of the present invention uses resistance to generate a reference voltage with a positive temperature coefficient, and then inputs the reference voltage with a positive temperature coefficient into the temperature compensation circuit, so that the temperature compensation circuit changes with temperature To adaptively compensate the output voltage, so that a stable output voltage is generated, thereby ensuring the normal operation of subsequent circuits. In addition, the temperature-compensated power starting circuit of the present invention does not need to be provided with a bandgap circuit and a deviation circuit, which has the advantage of simplifying the design, thereby reducing the production cost.

FIG. 1 is a schematic diagram of a power starting circuit 1 . The circuit structure of the power start-up circuit 1 is shown in Figure 1, which includes complementary metal-oxide-semiconductor (Complementary Metal-Oxide-Semiconductor, hereinafter referred to as CMOS) circuits of the front and rear stages, and the front-stage CMOS circuit includes serially connected A P-type transistor and a plurality of N-type transistors, and the subsequent CMOS circuit includes a P-type transistor and an N-type transistor connected in series. The front-stage and rear-stage CMOS circuits can respectively divide the system voltage VDD through transistors connected in series. In operation, when the system voltage VDD is greater than the sum of the threshold voltages (Threshold Voltage, Vth) of multiple N-type transistors in the front-stage CMOS circuit, it means that the system power supply is stable, and the subsequent CMOS circuit can be started to provide high voltage reference voltage VCOMP.

Under the circuit structure of the power start-up circuit 1 , the reference voltage VCOMP will vary with the operating temperature of the circuit itself or the temperature of the surrounding environment. Specifically, since the power starting circuit 1 is composed of multiple transistors with negative temperature coefficients, the reference voltage VCOMP also has negative temperature coefficients. For example, when the operating temperature rises, the resistance value of the MOSFET and the critical voltage Vth decrease, causing the voltage division ratio of the front-stage and subsequent-stage CMOS circuits to change, thereby changing the judgment conditions and timing for the latter-stage CMOS circuit to provide the reference voltage VCOMP, At the same time, the magnitude of the reference voltage VCOMP will also be changed. Unfortunately, if the power start-up circuit 1 cannot provide the reference voltage VCOMP at the correct judgment condition and timing, or cannot provide the correct reference voltage VCOMP, subsequent circuits may fail to operate normally.

FIG. 2 is a schematic diagram of a power starting circuit 2 with temperature compensation. The power starting circuit 2 includes a comparator 20 , a bandgap (Bandgap) circuit 21 , a bias (Bias) circuit 22 and resistors R3 and R4 . The circuit structure of the power starting circuit 2 is shown in FIG. 2 . In operation, the bias circuit 22 is used to provide the bias current of the bandgap circuit 21; the bandgap circuit 21 is used to generate the bandgap voltage VBG to the negative input terminal of the comparator 20 according to the bias current. Resistors R3 and R4 can be equivalent to the post-stage COMS circuit of the power start-up circuit 1 , and are used to divide the system voltage VDD to generate a reference voltage VCOMP to the positive input terminal of the comparator 20 . Next, the comparator 20 is used to compare the reference voltage VCOMP with the bandgap voltage VBG to generate the output voltage OUT.

FIG. 3 is a voltage timing diagram of the power starting circuit 2 with temperature compensation in FIG. 2 . In FIG. 3 , when the reference voltage VCOMP is less than the bandgap voltage VBG, the output voltage OUT is a low voltage; when the reference voltage VCOMP is greater than the bandgap voltage VBG, the output voltage OUT is a high voltage. In simple terms, since the bandgap circuit 21 can generate a stable bandgap voltage VBG, even if the reference voltage VCOMP changes with temperature, the comparison of the reference voltage VCOMP and the bandgap voltage VBG through the comparator 20 can be used in the comparator 20 The output terminal produces a stable output voltage OUT. In this way, the output voltage OUT generated by the power starting circuit 2 will not vary with temperature, thereby ensuring normal operation of subsequent circuits.

However, the applicant noticed that the circuit design of the bandgap circuit 21 and the deviation circuit 22 is relatively complicated, resulting in higher production costs. How to provide a power start-up circuit with simplified design and temperature compensation to reduce production cost is also one of the important issues in this field.

FIG. 4 is a schematic diagram of a power starting circuit 4 with temperature compensation according to an embodiment of the present invention. The power starting circuit 4 with temperature compensation can replace the power starting circuit 2 in FIG. 2 , and includes a current source 40 , a current amplifier 41 and a temperature compensation circuit 5 . The current source 40 is coupled to a system voltage VDD for generating an internal operating current I according to an internal operating voltage VI. The current amplifier 41 is coupled to the current source 40 and the system voltage VDD for generating an amplified current I*k and a reference voltage VREF corresponding to the amplified current I*k according to the internal operating current I and a parameter k. In this embodiment, the internal operating voltage VI and the reference voltage VREF have positive temperature coefficients, and the internal operating current I and the amplified current I*k have negative temperature coefficients. The temperature compensation circuit 5 is coupled to the current amplifier 41 for generating an output voltage OUT_COMP with temperature compensation according to the reference voltage VREF.

Structurally, the current source 40 includes a plurality of transistors M1 , M2 , M3 , M4 and a resistor R1 . The transistor M1 includes a first terminal coupled to the system voltage VDD; a second terminal coupled to a first node N1; and a control terminal coupled to a second node N2. The transistor M2 includes a first terminal coupled to the first node N1; a second terminal coupled to a second system voltage; and a control terminal coupled to the first node N1. The transistor M3 includes a first terminal coupled to the system voltage VDD; a second terminal coupled to the second node N2; and a control terminal coupled to the second node N2. The transistor M4 includes a first terminal coupled to the second node N2; a second terminal coupled to the resistor R1; and a control terminal coupled to the first node N1. The resistor R1 includes a first terminal coupled to the second terminal of the transistor M4 ; and a second terminal coupled to a second system voltage (such as but not limited to ground voltage). In this embodiment, the internal operating voltage VI is the voltage between the first terminal of the resistor R1 and the second terminal of the transistor M4, and the internal operating current I is the current flowing through the resistor R1.

The current amplifier 41 includes a transistor M5 and a resistor R2. The transistor M5 includes a first terminal coupled to the system voltage VDD; a second terminal coupled to the reference voltage VREF; and a control terminal coupled to the second node N2. The resistor R2 includes a first terminal coupled to the reference voltage VREF; and a second terminal coupled to a second system voltage (such as but not limited to ground voltage). In this embodiment, the amplified current I*k is the current flowing through the resistor R2.

In operation, in the current source 40, a plurality of transistors M1, M2, M3, M4 can be regarded as a current mirror, when the system voltage VDD turns on the transistors M1 and M2 to generate a current, the transistors M3 and M4 can generate A mirror current of the same magnitude as this current (i.e. the internal operating current I). Next, since the control terminal of the transistor M3 is coupled to the control terminal of the transistor M5, and the first terminals of the transistors M3 and M5 are coupled to the system voltage VDD, under the same semiconductor process conditions, the transistors M3 and M5 The voltage-to-current conversion characteristics can be regarded as linearly correlated (Linearly Correlated). In one embodiment, the aspect ratio (W/L Ratio) between the transistor M3 and the transistor M5 is 1:k. In this case, the conduction current of the transistor M5 is theoretically equal to the conduction current of the transistor M3 k times the size. Therefore, in the current amplifier 41, the amplified current I*k generated by the transistor M5 is k times the internal operating current I generated by the transistor M3.

（1）；

（2）； 其中VREF是參考電壓，k是參數，I是內部操作電流，m*R是電阻R2的電阻值，VI是內部操作電壓，且 n*R是電阻R1的電阻值。於一實施例中，電阻R1與電阻R2之間的電阻值比例為n：m，且電阻R1、R2的單位電阻值是R。 Furthermore, since the internal operating voltage VI is the cross-voltage generated by the internal operating current I flowing through the resistor R1, and the reference voltage VREF is the cross-voltage generated by the amplified current I*k flowing through the resistor R2, so according to Ohm's law, they can be deduced respectively Out of the size of the internal operating current I and the reference voltage VREF. Accordingly, the internal operating current I and the reference voltage VREF can be expressed by the following equations (1) and (2):

(1);

(2); where VREF is the reference voltage, k is the parameter, I is the internal operating current, m*R is the resistance value of the resistor R2, VI is the internal operating voltage, and n*R is the resistance value of the resistor R1. In one embodiment, the resistance ratio between the resistor R1 and the resistor R2 is n:m, and the unit resistance value of the resistors R1 and R2 is R.

According to the equation (1), since the internal operating voltage VI is a voltage across the resistor R1, the internal operating voltage VI has a positive temperature coefficient, that is, the internal operating voltage VI will increase as the temperature rises. According to equation (2), the reference voltage VREF is the product of the internal operating voltage VI and multiple parameters k, m, and n. Therefore, the reference voltage VREF has a positive temperature coefficient and will increase with temperature. In practical applications, those skilled in the art can select appropriate parameters k, m, and n according to different application requirements, so as to obtain an appropriate reference voltage VREF.

In one embodiment, the transistors M1, M3 and M5 are P-type transistors, the first terminals of the transistors M1, M3 and M5 are sources (Source), and the second terminals of the transistors M1, M3 and M5 are drains. Pole (Drain), and the control terminals of transistors M1, M3 and M5 are gates (Gate). In one embodiment, the transistors M2 and M4 are N-type transistors, the first ends of the transistors M2 and M4 are drains, the second ends of the transistors M2 and M4 are sources, and the control of the transistors M2 and M4 terminal is the gate, and the internal operating voltage VI is the voltage of the source of transistor M4.

FIG. 5 is a schematic diagram of a temperature compensation circuit 5 according to an embodiment of the present invention. The temperature compensation circuit 5 can replace the comparator 20 , the bandgap circuit 21 and the bias circuit 22 of FIG. 2 . The temperature compensation circuit 5 includes a current source 50 and a transistor M6. Structurally, the current source 50 is coupled between the system voltage VDD and the output voltage OUT_COMP for generating a positive temperature coefficient current I_BS according to the system voltage VDD, where the positive temperature coefficient is represented by +TC. In one embodiment, the current source 50 may be coupled to another system voltage different from the system voltage VDD, and generate the positive temperature coefficient current I_BS according to the other system voltage. The transistor M6 includes a first terminal coupled to the current source 50 and the output voltage OUT_COMP; a second terminal coupled to the second system voltage (such as but not limited to ground voltage); and a control terminal coupled to the reference The voltage VREF; wherein the transistor M6 generates a negative temperature coefficient current I_M6 according to the reference voltage VREF, and the negative temperature coefficient is represented by -TC here. In one embodiment, the transistor M6 is an N-type transistor, the first terminal of the transistor M6 is a drain, the second terminal of the transistor M6 is a source, and the control terminal of the transistor M6 is a gate.

In operation, when the operating temperature of the power startup circuit 4 rises, the reference voltage VREF rises to turn on the transistor M6, so that the transistor M6 pulls the output voltage OUT_COMP to the magnitude of the second system voltage (such as but not limited to ground voltage); At the same time, the system voltage VDD increases to increase the positive temperature coefficient current I_BS generated by the current source 50 , thereby pulling up the magnitude of the output voltage OUT_COMP. That is, when the operating temperature of the power start-up circuit 4 increases, the negative temperature coefficient current I_M6 decreases to decrease the output voltage OUT_COMP, and the positive temperature coefficient current I_BS increases to compensate the output voltage OUT_COMP. On the other hand, when the operating temperature of the power start-up circuit 4 drops, the negative temperature coefficient current I_M6 increases to increase the output voltage OUT_COMP, and the positive temperature coefficient current I_BS decreases to compensate the output voltage OUT_COMP.

To put it simply, in the embodiments of FIG. 4 and FIG. 5 of the present invention, the power starting circuit 4 uses resistors R1 and R2 to generate a reference voltage VREF with a positive temperature coefficient (the actual value of the reference voltage VREF can be obtained through the parameters k, m , n to set), and then input the reference voltage VREF with a positive temperature coefficient to the temperature compensation circuit 5, so that the temperature compensation circuit 5 adaptively compensates the output voltage OUT_COMP as the temperature changes, thus generating a stable output voltage OUT_COMP, This ensures that subsequent circuits can operate normally. It is worth noting that, compared with the power starting circuit 2 with temperature compensation in FIG. 2 , the power starting circuit 4 with temperature compensation of the present invention does not need to be equipped with a comparator 20, a bandgap circuit 21 and a deviation circuit 22, and has a simplified design. advantages, thereby reducing production costs.

To sum up, in the power start-up circuit 1 of FIG. 1 , it has the advantages of simple circuit design and low cost, but it does not have a temperature compensation function, which will cause subsequent circuits to fail to operate normally. In the power start-up circuit 2 of FIG. 2 , it has a temperature compensation function, but it has disadvantages of complex circuit design and high cost. In contrast, the temperature-compensated power starting circuit of the present invention can generate a stable output voltage, thereby ensuring normal operation of subsequent circuits, and also has the advantage of simplified design, thereby reducing production costs.

The present invention has been described by the above-mentioned related embodiments, but the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and equivalent arrangements included in the spirit and scope of the patent claims are included in the scope of the present invention.

1, 2, 4: Power start circuit 5: Temperature compensation circuit 20: Comparator 21:Band gap circuit 22: Deviation circuit 40, 50: current source 41: Current amplifier I: Internal operating current I*k: amplified current I_BS: positive temperature coefficient current I_M6: negative temperature coefficient current M1, M2, M3, M4, M5, M6: Transistor N1, N2: nodes +TC: positive temperature coefficient -TC: negative temperature coefficient R: resistance value R1, R2, R3, R4: Resistors k, m, n: parameters VBG: bandgap voltage VDD: system voltage VCOMP, VREF: reference voltage VI: Internal operating voltage Vth: critical voltage OUT, OUT_COMP: output voltage

Figure 1 is a schematic diagram of the power starting circuit. FIG. 2 is a schematic diagram of a power startup circuit with temperature compensation. FIG. 3 is a voltage timing diagram of the power starting circuit with temperature compensation in FIG. 2 . FIG. 4 is a schematic diagram of a power starting circuit according to an embodiment of the present invention. FIG. 5 is a schematic diagram of a temperature compensation circuit according to an embodiment of the present invention.

4: Power start circuit

40: Current source

41: Current amplifier

5: Temperature compensation circuit

I: Internal operating current

I*k: amplified current

M1, M2, M3, M4, M5: Transistor

N1, N2: nodes

R: resistance value

R1, R2: resistance

k, m, n: parameters

VDD: system voltage

VI: Internal operating voltage

VREF: reference voltage

OUT_COMP: output voltage

Claims (9)

A power starting circuit, comprising: a first current source, coupled to a first system voltage, used to generate an internal operating current according to an internal operating voltage; a current amplifier, coupled to the first current source and the The first system voltage is used to generate an amplified current and a reference voltage corresponding to the amplified current according to the internal operating current and a parameter; wherein the internal operating voltage and the reference voltage have a positive temperature coefficient, and the internal operating current and the amplified current has a negative temperature coefficient; and a temperature compensation circuit, coupled to the current amplifier, includes: a second current source, coupled between the first system voltage and the output voltage, for according to the The first system voltage generates a positive temperature coefficient current; a first transistor includes a first terminal coupled to the second current source and the output voltage; a second terminal coupled to the second system voltage and a control terminal coupled to the reference voltage; wherein the first transistor generates a negative temperature coefficient current according to the reference voltage; wherein when an operating temperature of the power starting circuit rises, the negative temperature coefficient current decreases causing the output voltage to drop and the positive temperature coefficient current to rise to compensate for the output voltage; and wherein when the operating temperature of the power startup circuit drops, the negative temperature coefficient current rises to raise the output voltage and the positive The temperature coefficient current drops to compensate for this output voltage. The power starting circuit as described in claim 1, wherein the first current source includes: a second transistor, including a first terminal, coupled to the first system voltage; a second terminal, coupled to a first system voltage a node; and a control terminal coupled to a second node; A third transistor includes a first terminal coupled to the first node; a second terminal coupled to a second system voltage; and a control terminal coupled to the first node; a fourth The transistor includes a first terminal coupled to the first system voltage; a second terminal coupled to the second node; and a control terminal coupled to the second node; a fifth transistor, Including a first end, coupled to the second node; a second end; and a control end, coupled to the first node; and a first resistor, including a first end, coupled to the fifth the second terminal of the transistor; and a second terminal coupled to the second system voltage; wherein the internal operating voltage is the voltage of the first terminal of the first resistor and the second terminal of the fifth transistor , and the internal operating current is the current flowing through the first resistor. The power starting circuit as described in claim 2, wherein the current amplifier comprises: a sixth transistor comprising a first terminal coupled to the first system voltage; a second terminal coupled to a reference voltage; and a control terminal, coupled to the second node; and a second resistor, including a first terminal, coupled to the reference voltage; and a second terminal, coupled to the second system voltage; wherein the amplifying The current is the current flowing through the second resistor. The power starting circuit as claimed in claim 3, wherein the aspect ratio between the fourth transistor and the sixth transistor is 1:k, and k is the parameter. The power starting circuit as described in claim item 3, wherein the reference voltage is expressed by the following equation:

Where VREF is the reference voltage, k is the parameter, I is the internal operating current, m*R is the resistance value of the second resistor, VI is the internal operating voltage, and n*R is the resistance value of the first resistor . The power starting circuit as described in claim 3, wherein the second transistor, the fourth transistor and the sixth transistor are P-type transistors, and the second transistor, the fourth transistor and the sixth transistor The first end of the transistor is a source, the second end of the second transistor, the fourth transistor, and the sixth transistor is a drain, and the second transistor, the fourth transistor, and The control end of the sixth transistor is a gate. The power starting circuit as described in claim 2, wherein the third transistor and the fifth transistor are N-type transistors, the first terminals of the third transistor and the fifth transistor are drains, the The second terminals of the third transistor and the fifth transistor are sources, and the control terminals of the third transistor and the fifth transistor are gates. The power starting circuit as claimed in claim 7, wherein the internal operating voltage is the voltage of the source of the fifth transistor. The power starting circuit as claimed in claim 1, wherein the first transistor is an N-type transistor, the first terminal of the first transistor is a drain, and the second terminal of the first transistor is a source , and the control terminal of the first transistor is a gate.

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