TWI416301B - Voltage and current reference circuit - Google Patents

Abstract

A voltage and current reference circuit is provided, including a voltage and current reference circuit with a positive temperature coefficient and a voltage and current reference circuit with a negative temperature coefficient connected in parallel. The voltage and current reference circuit with a positive temperature coefficient uses the positive temperature coefficient of the Vgs difference to generate a current with positive temperature coefficient, and the voltage and current reference circuit with a negative temperature coefficient uses the negative temperature characteristic of BJT to generate a current with negative temperature coefficient. By adding the two currents together, the output current reference is insensitive to temperature changes. A temperature-insensitive voltage reference can also be obtained.

Description

Reference voltage and current circuit

The present invention relates to a reference voltage and current circuit, and more particularly to a reference voltage and current circuit that is less affected by ambient operating temperatures.

In theory, the primary function of an ideal reference voltage and current circuit is to generate a fixed voltage or current regardless of device loading, power supply variation, or temperature. Therefore, the reference voltage and current circuit is the core of a voltage source or a current source, and is also widely used in various circuit devices, such as a Line Voltage Rated (LVR) device and a constant current device.

However, due to process, circuit design, and material characteristics, the reference voltage and current circuits that are actually fabricated typically do not produce the desired fixed voltage or current. Therefore, in the specification of the reference voltage and current circuit, it is often necessary to list the actual electrical characteristics of the reference voltage and current circuit, for example, temperature coefficient, temperature hysteresis, and other temperature-related indicators. For the designer's reference. Among them, the temperature coefficient is a parameter that designers often must incorporate into design considerations. The temperature coefficient refers to the degree of change of the reference voltage and current output by the reference voltage and current circuit with the external operating temperature, and may be a positive temperature coefficient or a negative temperature coefficient. The positive temperature coefficient refers to the increase of the reference voltage and current of the output as the external operating temperature increases, and the negative temperature coefficient refers to the decrease of the reference voltage and current of the output as the external operating temperature increases. Since the change in temperature may have different effects on the constituent elements in the circuit, the effect of the temperature change easily makes the electrical characteristics of the circuit less than expected. Therefore, a stable reference voltage and current circuit is an important issue for designers, and it is also a top priority in the industry.

Based on the above-mentioned shortcomings of the prior art, the main purpose of the present invention is to provide a reference voltage and current circuit that is less affected by ambient operating temperature to maintain circuit stability, and is suitable for various circuit designs and reduces the design of circuit designers. Difficulty.

Another object of the present invention is to provide a reference voltage and current circuit that is less affected by ambient operating temperature, and has a simple structure, a small area, is easy to manufacture, and is competitive in the market.

To achieve the above object, the present invention provides a reference voltage and current circuit comprising a positive temperature coefficient reference voltage and current circuit, and a negative temperature coefficient reference voltage and current circuit in parallel. Wherein the positive temperature coefficient reference voltage and current circuit generates a positive temperature coefficient current by using a positive temperature coefficient of a potential difference (Vgs) between a gate and a source of the transistor, and the current The negative temperature coefficient reference voltage and current circuit uses the negative temperature characteristic of BJT to generate a negative temperature system. The number of currents. In turn, the two currents are added to produce a reference current that is less affected by temperature, thereby obtaining an output reference voltage value that is less affected by temperature.

For a more detailed and detailed understanding of the objects, functions and structural features of the invention, the embodiments can be implemented and illustrated in the drawings.

The first figure shows a schematic diagram of the design of the reference voltage and current circuit of the present invention. In order to generate a reference current that is less affected by temperature, the main structure must therefore be carefully selected to produce a positive temperature coefficient current and a negative temperature coefficient current, and then the positive temperature coefficient current and the negative temperature coefficient The currents are added together, and by a temperature effect that cancels out each other, a reference current that is less affected by temperature is obtained. As shown, the reference voltage and current circuit design architecture 100 of the present invention includes a positive temperature coefficient reference voltage and current circuit 101, and a negative temperature coefficient reference voltage and current circuit 102 in parallel, and the two currents are added together. It is a reference current 103 that is less affected by temperature.

It is worth noting that the positive temperature coefficient reference voltage and current circuit uses a positive temperature coefficient of the difference between the potential (Vgs) between the gate and the source of the transistor to generate a positive temperature coefficient. The current, and the negative temperature coefficient reference voltage and current circuit utilizes a negative temperature characteristic of a bipolar junction transistor (BJT) to generate a negative temperature coefficient current. In turn, the two currents are added to produce one A reference current that is less affected by temperature, thereby obtaining an output reference voltage value that is less affected by temperature.

The second figure shows a schematic diagram of an embodiment of a PMOS current mirror of a reference voltage and current circuit of the present invention. As shown, the positive temperature coefficient reference voltage and current circuit 101 is implemented by a PMOS current mirror 201, which is composed of a transistor M _S1 , a transistor M _S2 , and a resistor R _S , wherein the transistor M _S1 and the source of the transistor M _S2 are respectively connected to the power source, and the inflowing power is represented by I _S1 and I _S2 respectively; the transistor M _S1 is connected to the gate of the transistor M _S2 and connected to the transistor M _S2 The source; the drain of the transistor M _S2 is grounded, and the drain of the transistor M _S1 is the series resistor R _S and then grounded. In contrast, the negative temperature coefficient reference voltage and current circuit 102 is implemented by a PMOS current mirror 202, which is composed of a current mirror 202 transistor M _B1 , a transistor M _B2 , a bipolar transistor BJT , and a resistor R _B . The source of the transistor M _B1 and the transistor M _B2 are respectively connected to the power source, and the inflowing electricity is represented by I _B1 and I _B2 respectively; the transistor M _B1 is connected to the gate of the transistor M _B2 and connected to the electricity. M _B2 source transistor pole; M _B2 crystal drain electrode is electrically grounded with a bipolar transistor BJT, and the drain electrode electrically M _B1 crystals series resistor R _B is then ground.

The positive temperature coefficient reference voltage and current circuit 101 and the negative temperature coefficient reference voltage and current circuit 102 are connected in parallel through a PMOS current mirror 203. The current mirror 201 and the current mirror 202 are respectively connected to the current mirror 203, and the current after the two currents are added is the reference current outputted by the present invention, and the voltage difference obtained by taking out the reference current flowing through the resistor R _O is The reference voltage output by the present invention.

The relationship between the voltage and current generated by the implementation of the second graph can be explained by the following equation.

The third figure shows a schematic diagram of the reference current I _REF calculated according to the simulation of the circuit of the second figure. The X axis is the scan VDD voltage, and the Y axis is the IREF current value. The IREF current value is scanned every 20 ° C from -40 ° C to 140 ° C. The portion indicated by the broken line is the positive temperature coefficient reference voltage and the reference current output by the current circuit 101, and the solid line portion is the reference current output by the reference voltage and current circuit of the present invention. As shown, the reference current IREF current value output by the conventional circuit (ie, the positive temperature coefficient reference voltage and current circuit 101) increases as the temperature increases, and the reference voltage and current circuit of the present invention outputs The reference current IREF current value is relatively stable and does not change with temperature rise.

Similarly, the fourth figure shows a schematic diagram of the reference voltage V _REF obtained by the simulation of the circuit of the second figure. The X axis is the scan VDD voltage, and the Y axis is the V _REF voltage value, which is a VREF voltage value that is scanned every 20 ° C from -40 ° C to 140 ° C. The portion indicated by the broken line is the negative temperature coefficient reference voltage and the reference current output by the current circuit 102, and the solid line portion is the reference voltage output by the reference voltage and current circuit of the present invention. As shown, the reference voltage VREF voltage value output by the conventional circuit (ie, the negative temperature coefficient reference voltage and current circuit 102) decreases as the temperature increases, and the reference voltage and current circuit of the present invention outputs The reference voltage VREF voltage value is relatively stable and does not change with temperature rise.

Through the above embodiments of the present invention, compared with the prior art, the present invention has the advantage that it is less affected by the ambient operating temperature to maintain circuit stability, and is suitable for various circuit designs, reducing the design difficulty of the circuit designer. The utility model has the advantages of simple structure, small area, easy manufacture and market competitiveness.

Therefore, the reference voltage and current circuit of the present invention can achieve the intended purpose and effect by the disclosed technology, and conforms to the novelty, advancement and industrial utilization requirements of the invention patent.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

100‧‧‧Reference voltage and current circuits

101‧‧‧ Positive temperature coefficient reference voltage and current circuit

102‧‧‧Negative temperature coefficient reference voltage and current circuit

103‧‧‧Reference current not affected by temperature

201‧‧‧current mirror

M _S1 ‧‧‧O crystal

M _S2 ‧‧‧O crystal

R _S ‧‧‧resistance

202‧‧‧current mirror

M _B1 ‧‧‧O crystal

M _B2 ‧‧‧O crystal

BJT‧‧‧ bipolar transistor

R _B ‧‧‧resistance

203‧‧‧current mirror

R _O ‧‧‧resistance

The first figure shows the design of the reference voltage and current circuit of the present invention. intention.

The second figure shows a schematic diagram of an embodiment of a PMOS current mirror of a reference voltage and current circuit of the present invention.

The third figure shows a schematic diagram of the reference current I _REF calculated according to the simulation of the circuit of the second figure.

The fourth figure shows a schematic diagram of the reference voltage V _REF obtained from the simulation of the circuit of the second figure.

100. . . Reference voltage and current circuit

101. . . Positive temperature coefficient reference voltage and current circuit

102. . . Negative temperature coefficient reference voltage and current circuit

103. . . Reference current unaffected by temperature

Claims (4)

A reference voltage and current circuit comprising a positive temperature coefficient reference voltage and current circuit, and a negative temperature coefficient reference voltage and current circuit in parallel; wherein the positive temperature coefficient reference voltage and current circuit utilizes a gate in the transistor (gate) a positive temperature coefficient of the potential difference (Vgs) with the source to generate a positive temperature coefficient, and the negative temperature coefficient reference voltage and current circuit utilizes the negative temperature characteristic of the BJT to generate a negative temperature coefficient The current is further added to generate a reference current that is less affected by temperature, thereby obtaining an output voltage reference value that is less affected by temperature. The reference voltage and current circuit according to claim 1, wherein the positive temperature coefficient reference voltage and current circuit is a current mirror, wherein the current mirror is composed of a transistor (M _S1 ), a transistor ( M _S2 ), and a resistor (R _S ), wherein the transistor (M _S1 ) and the transistor (M _S2 ) source are respectively connected to a power source; the transistor (M _S1 ) and the transistor ( M _S2) gates connected and connected to the source of the transistor (M _S2) of the electrode; the transistor (M _S2) of the drain is grounded, and the power drain crystal (M _S1) of the electrode is connected in series the resistance (R _S ) and then ground. The reference voltage and current circuit according to claim 1, wherein the negative temperature coefficient reference voltage and current circuit is a current mirror, wherein the current mirror is composed of a transistor (M _B1 ), a transistor ( M _B2 ), a bipolar transistor (BJT), and a resistor (R _B ), wherein the transistor (M _B1 ) and the transistor (M _B2 ) source are respectively connected to a power source; the transistor (M _B1) a gate connected to the transistor (M _B2), and connected to the power source transistor (M _B2) of the electrode; the transistor (M _B2) of the drain in series of the bipolar transistor (BJT) After grounding, the drain of the transistor (M _B1 ) is connected to the series resistor (R _B ) and then grounded. For example, the reference voltage and current circuit described in claim 1 wherein the positive temperature coefficient reference voltage and current circuit and the negative temperature coefficient reference voltage and current circuit are connected in parallel through a current mirror, and the two currents are added. The subsequent current is the reference current outputted by the present invention.