TWI789671B - Reference circuit with temperature compensation - Google Patents

Abstract

The present invention discloses a reference circuit with temperature compensation, which is characterized in that a current output circuit is designed to receive a reference voltage from a bias voltage generation circuit, generates two reference currents with opposite temperature variation characteristics, and then merge them into a precise current with temperature compensation. In addition, a voltage output circuit is designed to receive a reference voltage from a bias voltage generation circuit, which includes several field-effect transistors operating in saturation regions, and a precision voltage is increased with threshold voltages of the field-effect transistors to compensate for the temperature variation. Resistors can be incorporated or sizes of the field effect transistors can be changed to adjust the output current, output voltage or the temperature variation characteristics.

Description

Reference circuit with temperature compensation function

The present invention relates to a reference circuit, especially a reference circuit with temperature compensation function, which outputs stable voltage and current values when the temperature changes.

Reference circuits are widely used in various electronic components to provide precise voltage or current. For example, comparators need precise reference voltage as a comparison reference, or in the design of high-speed input and output circuits, USB interfaces, and SATA interfaces. It is necessary to use precise reference voltage and reference current for impedance matching. The ideal reference voltage and reference current are stable and will not change with the process, temperature, and power supply voltage. In addition, the power consumption of the reference circuit should be as small as possible.

Taiwan Patent No. I367412 discloses a reference circuit that provides precise voltage and precise current at the same time, using a differential voltage reference circuit, a positive temperature coefficient correction circuit, a threshold voltage superposition circuit and a precise current generation circuit to compensate for temperature variation effects . However, the band-drop voltage reference circuit needs to use a bipolar junction transistor (BJT), which consumes more power than a field-effect transistor. In addition, the positive temperature coefficient correction circuit includes an operational amplifier, which requires a larger circuit area to realize .

In Taiwan Patent No. I485546, a reference circuit for providing precise voltages is disclosed, which only uses a combination of a plurality of field effect transistors and two resistors. However, the precise current is not provided, and another resistor is directly connected between the output voltage and ground, A large resistance value or current value is required to output a precise voltage with a high voltage value, which will increase the circuit area or power consumption, and introduce more noise interference at the same time.

In Taiwan Patent No. I521325, a reference circuit for providing precise voltage and precise current is disclosed, which is only composed of a plurality of field effect transistors and three resistors. However, the precise voltage and the precise current cannot be adjusted separately. In addition, the same disadvantage as Taiwan Patent No. I485546 is that there is a resistor directly connected between the output voltage and ground, which requires a large resistance value or current value to output a precise voltage with a higher voltage value, so it will increase Circuit area or power consumption, while introducing more noise interference. Based on the above problems, the present invention discloses a reference circuit that simultaneously generates a precise voltage and a precise current, and can separately adjust the numerical value and temperature variation characteristics of the precise voltage and precise current, while taking into account the advantages of saving circuit area and low power.

The invention discloses a precise current reference circuit with temperature compensation function, which includes a bias voltage generation circuit and a current output circuit. The bias voltage generation circuit is used to generate a first reference voltage and a second reference voltage. The current output circuit uses a field effect transistor to receive the first reference voltage, and the temperature variation characteristic is consistent with the current of the bias voltage generation circuit. A first reference current, and use a plurality of field effect transistors and a resistor to receive the second reference voltage, wherein the field effect transistors are all operated in the saturation region, and generate a second reference current, so that the first The current value of the two reference currents is positively correlated with the threshold voltage of the field effect transistor, and the temperature variation characteristic is opposite to the current of the bias voltage generating circuit. The first reference current and the second reference current are combined to form the precision current, which has the effect of compensating temperature variation.

The above precision current reference circuit with temperature compensation function, wherein the bias generating circuit includes: a first resistor, one end of which is grounded; a first N-type field effect transistor, with a source connected to the first resistor The other end of the device; a second N-type field effect transistor with a source grounded, and with a gate and a drain connected to the gate of the first N-type field effect transistor; a third N-type field effect transistor A type field effect transistor with a source connected to the drain of the first N-type field effect transistor; a fourth N-type field effect transistor with a source connected to the second N-type field effect transistor The drain, and has a gate and a drain are connected to the gate of the third N-type field effect transistor; a first P-type field effect transistor, has a source connected to a power supply, and has A gate and a drain are both connected to the drain of the third N-type field effect transistor; a second P-type field effect transistor has a source connected to the power supply and a gate connected to the first A gate of a P-type field effect transistor, and a drain connected to the drain of the fourth N-type field effect transistor; wherein the voltage of the gate of the first P-type field effect transistor is the voltage of the first P-type field effect transistor A reference voltage, the gate voltage of the third N-type field effect transistor is the second reference voltage.

The above precision current reference circuit with temperature compensation function, wherein the current output circuit includes: a fifth P-type field effect transistor, having a source connected to the power supply, and a gate connected to the first reference voltage, And have a drain to generate a first reference current; a sixth N-type field effect transistor with a gate connected to the second reference voltage; a second resistor with one end connected to ground and the other end connected to the sixth The source of the N-type field effect transistor; a sixth P-type field effect transistor, with a source connected to the power supply, a gate and a drain both connected to the sixth N-type field effect transistor drain; a seventh P-type field effect transistor having a source connected to the power supply, having a gate connected to the gate of the sixth P-type field effect transistor, and having a drain generating a second reference current, and connected to the drain of the fifth P-type field effect transistor.

The above precision current reference circuit with temperature compensation function, wherein the fifth P-type field effect transistor, the sixth P-type field effect transistor or the seventh P-type field effect transistor can be changed size, so as to adjust the magnitude of the first reference current or the second reference current, and adjust the magnitude of the precision current and the temperature variation characteristic.

The above precision current reference circuit with temperature compensation function further includes a voltage output circuit for outputting a precision voltage, including a plurality of field effect transistors, receiving the first reference voltage or the second reference voltage to generate the precision voltage ; Wherein the field effect transistors are operated in the saturation region, and the precision voltage rises with the threshold voltage of the field effect transistors to compensate the temperature variation effect.

In the above precision current and precision voltage reference circuit with temperature compensation function, the voltage output circuit includes: an eighth P-type field effect transistor, with a source connected to the power supply, and a gate connected to the first reference Voltage; an eighth N-type field effect transistor, having a source grounded, having a gate and a drain all connected to the drain of the eighth P-type field effect transistor, and using the eighth P-type field effect transistor The junction between the effect transistor and the eighth N-type field effect transistor is used as the precise voltage; wherein the eighth N-type field effect transistor can be replaced by a ninth P-type field effect transistor, which has a source The electrode is connected to the drain electrode of the eighth P-type field effect transistor, and a gate electrode and a drain electrode are both grounded.

In the above precision current and precision voltage reference circuit with temperature compensation function, the voltage output circuit further includes a third resistor connected between the eighth P-type field effect transistor and the eighth N-type field effect transistor between the eighth P-type field effect transistor and the ninth P-type field effect transistor, or between the gate and the drain of the eighth N-type field effect transistor, and can Adjust the resistance value of the third resistor, the size of the eighth N-type field effect transistor or the size of the ninth P-type field effect transistor to change the voltage value of the precision voltage.

The present invention discloses a precision voltage reference circuit with temperature compensation function, which includes a bias voltage generating circuit to generate a first reference voltage; a voltage output circuit including a plurality of field effect transistors to receive the first reference voltage and generate the first reference voltage precision voltage; where the field effects The transistors all operate in the saturation region, and the precision voltage increases with the threshold voltage of the field effect transistors to compensate for temperature variation effects.

The above precision voltage reference circuit with temperature compensation function, wherein the bias generating circuit includes: a first resistor, one end of which is grounded; a first N-type field effect transistor, with a source connected to the first resistor The other end, and has a gate and a drain; a second N-type field effect transistor, has a source grounded, and has a gate and a drain are connected to the first N-type field effect transistor A gate of the crystal; a first P-type field effect transistor having a source connected to a power supply, and having a gate and a drain both connected to the drain of the first N-type field effect transistor; The second P-type field effect transistor has a source connected to the power supply, a gate connected to the gate of the first P-type field effect transistor, and a drain connected to the second N-type field effect transistor. The drain of the field effect transistor, wherein the gate voltage of one of the field effect transistors is the first reference voltage.

The above precision voltage reference circuit with temperature compensation function, wherein the bias voltage generating circuit further includes: a third N-type field effect transistor, having a source and a drain, connected to the first N-type field effect transistor and between the first P-type field effect transistor; a fourth N-type field effect transistor, having a source and a drain, connected to the second N-type field effect transistor and the second P-type field effect transistor Between the effect transistors, there is a gate connected to the drain of the second P-type field effect transistor and the gate of the third N-type field effect transistor.

In the above precision voltage reference circuit with temperature compensation function, the voltage output circuit includes: an eighth P-type field effect transistor, having a source connected to the power supply, and a gate connected to the first reference voltage; The eighth N-type field effect transistor has a source grounded, has a gate and a drain connected to the drain of the eighth P-type field effect transistor, and uses the eighth P-type field effect transistor And the contact between the eighth N-type field effect transistor is used as the precise voltage; wherein the eighth N-type field effect transistor can be replaced by a ninth P-type field effect transistor, which has a source connected to The drain of the eighth P-type field effect transistor has a gate and a drain both grounded.

The above precision voltage reference circuit with temperature compensation function, wherein the voltage output circuit further includes a third resistor connected between the eighth P-type field effect transistor and the eighth N-type field effect transistor, or connected between the eighth P-type field effect transistor and the ninth P-type field effect transistor, or between the gate and the drain of the eighth N-type field effect transistor, and can adjust the The resistance value of the three resistors, the size of the eighth N-type field effect transistor or the size of the ninth P-type field effect transistor change the voltage value of the precision voltage.

Compared with the previous proposal, the above-mentioned reference circuit with temperature compensation function has the advantage of good power supply rejection ratio (PSRR), which means that when the power supply is disturbed by noise, the output reference voltage variation is relatively small; in addition, it has A wide operating range of power supply voltage can be operated within the commonly used range of 1.8V to 5.5V, and the output reference voltage and reference current can be adjusted. For example, the commonly used reference voltage is 1.2V, and the output The reference voltage is adjusted around the threshold voltage (Vth) of the field effect transistor. In addition, this architecture can be realized only by using field effect transistors. Compared with the previous solution requiring bipolar junction transistors (BJT), the manufacturing process is simpler, and the circuit area and power consumption can be saved.

This paragraph extracts and compiles some features of the present invention; other features will be described in subsequent paragraphs. It is intended to cover various modifications and similar arrangements included within the spirit and scope of claims that follow.

10: Bias voltage generating circuit

20: Current output circuit

30: Voltage output circuit

Mn1: the first N-type field effect transistor

Mn2: the second N-type field effect transistor

Mn3: the third N-type field effect transistor

Mn4: the fourth N-type field effect transistor

Mn5: fifth N-type field effect transistor

Mn6: the sixth N-type field effect transistor

Mn7: the seventh N-type field effect transistor

Mn8: Eighth N-type field effect transistor

Mp1: the first P-type field effect transistor

Mp2: The second P-type field effect transistor

Mp3: The third P-type field effect transistor

Mp4: The fourth P-type field effect transistor

Mp5: the fifth P-type field effect transistor

Mp6: the sixth P-type field effect transistor

Mp7: the seventh P-type field effect transistor

Mp8: Eighth P-type field effect transistor

Mp9: the ninth P-type field effect transistor

R1: first resistor

R2: second resistor

R3: Third resistor

FIG. 1 shows the structure of a precision current reference circuit with temperature compensation function according to the first embodiment of the present invention.

Figure 2 shows the architecture of a precision current and precision voltage reference circuit with temperature compensation.

Figure 3 shows the structure of a precision voltage reference circuit with temperature compensation function.

Fig. 4 shows another state of the voltage output circuit in Fig. 3.

Fig. 5 shows another state of the voltage output circuit in Fig. 3.

Fig. 6 shows another state of the voltage output circuit in Fig. 4.

FIG. 7 shows another state of the bias generating circuit in FIG. 3 .

The present invention will be more specifically described with reference to the following examples. Please note that the following descriptions of the embodiments of the present invention are for descriptive purposes only; it is not meant to describe the present invention exhaustively or to limit it to the disclosed form.

Please refer to FIG. 1 for the first embodiment of the present invention, which shows a precision current reference circuit with temperature compensation function, including a bias voltage generation circuit 10 and a current output circuit 20 . The bias generating circuit 10 is used to generate a first reference voltage Vref1 and a second reference voltage Vref2. The current output circuit 20 uses a field effect transistor (fifth P-type field effect transistor Mp5) to receive the first reference voltage Vref1, and generates a first reference current Iref1 whose temperature variation characteristic is consistent with the current of the bias voltage generating circuit 10. , and use a plurality of field effect transistors (sixth P-type field effect transistor Mp6, seventh P-type field effect transistor Mp7, sixth N-type field effect transistor Mn6) and a second resistor R2 to receive the first Two reference voltage Vref1. Wherein the field effect transistors are all operated in the saturation region, and generate a second reference current Iref2, so that the current value of the second reference current Iref2 is positively correlated with the threshold voltage (Vth) of the field effect transistors, and the temperature variation The characteristic is opposite to the current of the bias generating circuit 10 . The first reference current Iref1 and the second reference current Iref2 are combined to form the precision current Icomp, which has the effect of compensating temperature variation.

The above precision current reference circuit with temperature compensation function, wherein the bias voltage generating circuit 10 includes: a first resistor R1, one end of which is grounded; a first N-type field effect transistor Mn1, with a source connected to the The other end of the first resistor R1; a second N-type field effect transistor Mn2 having a source grounded, and having a gate and a drain all connected to the gate of the first N-type field effect transistor Mn1 pole; a third N-type field effect transistor Mn3, with a source connected to the drain of the first N-type field effect transistor Mn1; a fourth N-type field effect transistor Mn4, with a source connected to The drain of the second N-type field effect transistor Mn2, and a gate and a drain are connected to the gate of the third N-type field effect transistor Mn3; a first P-type field effect transistor Mp1 , having a source connected to a power supply, and having a gate and a drain both connected to the drain of the third N-type field effect transistor Mn3; a second P-type field effect transistor Mp2 having a source has a gate connected to the gate of the first P-type field effect transistor Mp1, and has a drain connected to the drain of the fourth N-type field effect transistor Mn4. The gate voltage of the first P-type field effect transistor Mp1 is the first reference voltage Vref1, and the gate voltage of the third N-type field effect transistor Mn3 is the second reference voltage.

The above precision current reference circuit with temperature compensation function, wherein the current output circuit 20 includes: a fifth P-type field effect transistor Mp5, having a source connected to the power supply, and a gate connected to the first reference Voltage Vref1, and has a drain to generate a first reference current Iref1; a sixth N-type field effect transistor Mn6, has a gate connected to the second reference voltage Vref2; a second resistor R2, one end of which is grounded, The other end is connected to the source of the sixth N-type field effect transistor Mn6; a sixth P-type field effect transistor Mp6 has a source connected to the power supply, a gate and a drain connected to the The drain of the sixth N-type field effect transistor Mn6; a seventh P-type field effect transistor Mp7, having a source connected to the power supply, and a gate connected to the sixth P-type field effect transistor Mp6 The gate and a drain generate a second reference current Iref2, and are connected to the drain of the fifth P-type field effect transistor Mp5.

In the above-mentioned precise current reference circuit with temperature compensation function, the current of the fifth P-type field effect transistor Mp5 is the first reference current Iref1, and the current of the bias voltage generating circuit 10 increases with temperature rise The temperature variation characteristics of the current value; the current of the sixth N-type field effect transistor Mn6 is the same as the current of the second resistor R2, marked as I _R2 , and the relationship is: "V _GSN1 +V _GSN3 =V _GSN6 +( I _R2 *R2)", wherein V _GSN1 is the voltage between the gate and the source of the first N-type field effect transistor Mn1, and the rest are analogized. The above relational formula can be organized as: "I _R2 =(V _GSN1 +V _GSN3 -V _GSN6 )/R2", when other parameters are fixed, V _GSN1 , V _GSN3 and V _GSN6 will all increase with the field effect voltage The threshold voltage (Vth) of the crystal is positively correlated, but the threshold voltage (Vth) has a temperature variation characteristic that decreases as the temperature rises, so the current of the sixth N-type field effect transistor Mn6 and the second resistor R2 I _R2 also has a temperature variation characteristic that decreases as the temperature rises, so that the currents of the sixth P-type field effect transistor Mp6 and the seventh P-type field effect transistor Mp7 (that is, the second reference current Iref2) also have A characteristic of temperature variation that decreases with increasing temperature. To sum up, the first reference current Iref1 and the second reference current Iref2 have opposite temperature variation characteristics, so that the summed precision current Icomp has the effect of compensating temperature variation.

The above precision current reference circuit with temperature compensation function, wherein the size of the fifth P-type field effect transistor Mp5, the sixth P-type field effect transistor Mp6 or the seventh P-type field effect transistor Mp7 can be changed, The magnitude of the first reference current Iref1 or the second reference current Iref2 is adjusted, and the magnitude of the precision current Icomp and temperature variation characteristics are adjusted.

The above precision current reference circuit with temperature compensation function further includes a voltage output circuit 30 for outputting the precision voltage Vcomp, please refer to FIG. 2 . The voltage output circuit 30 includes a plurality of field effect transistors (the eighth P-type field effect transistor Mp8 and the eighth N-type field effect transistor Mn8), which receive the first reference voltage Vref1 to generate the precision voltage Vcomp; wherein The field effect transistors are all operated in the saturation region, and the precise voltage Vcomp rises with the threshold voltage (Vth) of the field effect transistors to compensate the temperature variation effect.

In the above-mentioned voltage output circuit 30, regardless of the situation of adding the third resistor R3 (R3=0), the precise voltage Vcomp is the distance between the gate and the source of the eighth N-type field effect transistor Mn8 The voltage value of the voltage difference V _GSN8 is positively correlated with the current of the bias generating circuit 10 and the threshold voltage (Vth) of the field effect transistor. Since the current of the bias voltage generating circuit 10 has a temperature variation characteristic that increases as the temperature rises, and the threshold voltage (Vth) of the field effect transistor has a temperature variation characteristic that decreases as the temperature rises, the two temperature variation characteristics The temperature variation characteristics can be compensated by adding the opposite physical quantities. Adding the third resistor R3 can be used to adjust the voltage value of the precision voltage Vcomp.

Please refer to FIG. 3 for the third embodiment of the present invention, which shows a precision voltage reference circuit with temperature compensation function, including a bias voltage generation circuit 10 and a voltage output circuit 30 . The structure of the bias voltage generating circuit 10 and the voltage output circuit 30 is the same as that of Figure 2. This figure is used to illustrate that the precise voltage Vcomp and the precise current Icomp can be designed and adjusted separately, and based on the structure of this figure, it is explained that the Variations of the voltage output circuit 30.

Fig. 4 shows another state of the voltage output circuit 30 in Fig. 3. The difference between this Fig. 3 and Fig. 3 is that the positions of the eighth N-type field effect transistor Mn8 and the third resistor R3 are interchanged. The precision voltage Vcomp also has the effect of compensating the temperature variation characteristic.

Figure 5 shows another state of the voltage output circuit 30 in Figure 3. The difference between this figure and Figure 3 lies in the adjustment and connection method of the eighth N-type field effect transistor Mn8 and the third resistor R3. The source of the eighth N-type field effect transistor Mn8 is grounded, the gate is connected to the drain of the eighth P-type field effect transistor Mp8, and the drain is connected to one end of the third resistor R3. The third resistor The other end of the device R3 is connected to the gate of the eighth N-type field effect transistor Mn8, and the precise voltage Vcomp is obtained from the eighth N-type field effect transistor Mn8. The drains of the eight N-type field effect transistors Mn8 are connected, and this connection method also has the effect of compensating for temperature variation characteristics.

FIG. 6 shows another state of the voltage output circuit 30 in FIG. 4. The difference between this figure and FIG. 4 is that the eighth N-type field effect transistor Mn8 is replaced by a ninth P-type field effect transistor Mp9, The source of the ninth P-type field effect transistor Mp9 is connected to the drain of the eighth P-type field effect transistor Mp8, the gate and the drain are connected to one end of the third resistor R3, and the ninth P The type field effect transistor Mp9 can also exchange positions with the third resistor R3, and the above connection methods can make the precision voltage Vcomp have the effect of compensating temperature variation characteristics.

FIG. 7 shows another state of the bias generating circuit 10 in FIG. 3 . Wherein the bias generating circuit 10 comprises: a first resistor R1, one end of which is grounded; a first N-type field effect transistor Mn1, having a source connected to the other end of the first resistor R1, and having a a gate and a drain; a second N-type field effect transistor Mn2 having a source grounded, and having a gate and a drain both connected to the gate of the first N-type field effect transistor Mn1; A first P-type field effect transistor Mp1 has a source connected to a power supply, and a gate and a drain are connected to the drain of the first N-type field effect transistor Mn1; a second P Type field effect transistor Mp2 has a source connected to the power supply, a gate connected to the gate of the first P-type field effect transistor Mp1, and a drain connected to the second N-type field effect The drain of the transistor Mn2, wherein the gate voltage of the first P-type field effect transistor Mp1 is the first reference voltage Vref1.

The voltage output circuit 30 mentioned above can adjust the resistance value of the third resistor R3, the size of the eighth N-type field effect transistor Mn8 or the size of the ninth P-type field effect transistor Mp9, so as to change the precise voltage The voltage value of Vcomp.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field will not depart from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the appended patent application.

10: Bias voltage generating circuit

20: Current output circuit

30: Voltage output circuit

Mn1: the first N-type field effect transistor

Mn2: the second N-type field effect transistor

Mn3: the third N-type field effect transistor

Mn4: the fourth N-type field effect transistor

Mn5: fifth N-type field effect transistor

Mn6: the sixth N-type field effect transistor

Mp1: the first P-type field effect transistor

Mp2: The second P-type field effect transistor

Mp3: The third P-type field effect transistor

Mp4: The fourth P-type field effect transistor

Mp5: the fifth P-type field effect transistor

Mp6: the sixth P-type field effect transistor

Mp7: the seventh P-type field effect transistor

R1: first resistor

R2: second resistor

R3: Third resistor

Claims (8)

A reference circuit with temperature compensation function, comprising: a bias generating circuit, including a plurality of N-type field effect transistors, a plurality of P-type field effect transistors, and a first resistor, wherein the P-type field effect transistors The voltage of the gate of one of the crystals is set to a first reference voltage, and the voltage of the gate of one of the N-type field effect transistors is set to a second reference voltage; a current output circuit uses a field effect The transistor receives the first reference voltage, generates a first reference current whose temperature variation characteristics are consistent with the current of the bias voltage generating circuit, and uses a plurality of field effect transistors and a resistor to receive the second reference voltage, wherein the These field effect transistors all operate in the saturation region, and generate a second reference current, so that the current value of the second reference current is positively correlated with the threshold voltage of the field effect transistor, and the temperature variation characteristic and the bias generating circuit The current is opposite; the first reference current and the second reference current are merged into the precise current, and have the effect of compensating the temperature variation effect, wherein the current output circuit includes: a fifth P-type field effect transistor, with a source pole is connected to a power supply, has a gate connected to the first reference voltage, and has a drain to generate a first reference current; a sixth N-type field effect transistor has a gate connected to the second reference voltage; a second resistor, one end is grounded, and the other end is connected to the source of the sixth N-type field effect transistor; a sixth P-type field effect transistor has a source connected to the power supply, and a gate A pole and a drain are both connected to the drain of the sixth N-type field effect transistor; and A seventh P-type field effect transistor having a source connected to the power supply, a gate connected to the gate of the sixth P-type field effect transistor, and a drain generating a second reference current, And connected to the drain of the fifth P-type field effect transistor. The reference circuit as described in item 1 of the scope of the patent application, wherein one end of the first resistor is grounded; the N-type field effect transistors include: a first N-type field effect transistor with a source connected to the The other end of the first resistor; a second N-type field effect transistor having a source grounded, and having a gate and a drain both connected to the gate of the first N-type field effect transistor; The third N-type field effect transistor has a source connected to the drain of the first N-type field effect transistor; and a fourth N-type field effect transistor has a source connected to the second N-type field effect transistor The drain of the field effect transistor, and a gate and a drain connected to the gate of the third N-type field effect transistor; the P-type field effect transistors include: a first P-type field effect transistor Transistor having a source connected to a power supply, and having a gate and a drain both connected to the drain of the third N-type field effect transistor; and a second P-type field effect transistor having a The source is connected to the power supply, has a gate connected to the gate of the first P-type field effect transistor, and has a drain connected to the drain of the fourth N-type field effect transistor; wherein the first The gate voltage of the P-type field effect transistor is the first reference voltage, and the gate voltage of the third N-type field effect transistor is the second reference voltage. For the reference circuit described in item 1 of the scope of the patent application, the size of the fifth P-type field effect transistor, the sixth P-type field effect transistor or the seventh P-type field effect transistor can be changed, and the first P-type field effect transistor can be adjusted. The magnitude of the reference current or the second reference current, and adjust the magnitude of the precise current and the temperature variation characteristics. The reference circuit as described in item 1, item 2 or item 3 of the scope of the patent application, which further includes a voltage output circuit, including a plurality of field effect transistors, receiving the first reference voltage or the second reference voltage, A precise voltage is generated; wherein the field effect transistors are operated in a saturation region, and the precise voltage rises with the threshold voltage of the field effect transistors to compensate temperature variation effect. The reference circuit as described in item 4 of the scope of the patent application, wherein the voltage output circuit comprises: an eighth P-type field effect transistor having a source connected to the power supply and a gate connected to the first reference voltage and an eighth N-type field effect transistor having a source grounded, having a gate and a drain both connected to the drain of the eighth P-type field effect transistor, and with the eighth P-type field effect transistor The junction between the effect transistor and the eighth N-type field effect transistor is used as the precision voltage. The reference circuit described in item 5 of the scope of the patent application, wherein the voltage output circuit further includes a third resistor connected between the eighth P-type field effect transistor and the eighth N-type field effect transistor, or connected between the gate and the drain of the eighth N-type field effect transistor, and the resistance value of the third resistor and the size of the eighth N-type field effect transistor can be adjusted to change the precise voltage The voltage value. The reference circuit described in item 4 of the scope of the patent application, wherein the voltage output circuit includes: An eighth P-type field effect transistor having a source connected to the power supply and a gate connected to the first reference voltage; and a ninth P-type field effect transistor having a source connected to the first reference voltage The drains of the eight P-type field effect transistors have a gate and a drain that are both grounded. The reference circuit described in item 7 of the scope of the patent application, wherein the voltage output circuit further includes a third resistor connected between the eighth P-type field effect transistor and the ninth P-type field effect transistor, And the resistance value of the third resistor and the size of the ninth P-type field effect transistor can be adjusted to change the voltage value of the precision voltage.

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