KR19980065781A - Single power reference voltage generator circuit - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference voltage generator circuit of an analog-to-digital converter. More specifically, the present invention relates to an analog signal that converts an analog signal into a digital signal using differential voltages of the reference voltages output by applying a single power supply to the reference voltage generator circuit of the analog-digital converter. A short power supply reference voltage generation circuit of the converter, the first reference voltage generation unit receiving a power supply voltage from an external device and outputting a first reference voltage; A second reference voltage generator which receives the first reference voltage and outputs a second reference voltage; And a third reference voltage generator configured to receive the second reference voltage and the first reference voltage and output a third reference voltage. By applying the single power supply by such a device, there is an effect that the path of voltage supply is shortened.

Description

Single power reference voltage generator circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference voltage generator circuit of an analog-digital converter. Specifically, a differential voltage, that is, a positive reference voltage and a negative reference voltage applied by applying a single power supply to the reference voltage generator circuit of an analog-digital converter is applied. The present invention relates to a single power supply reference voltage generator circuit of an analog-to-digital converter that converts an analog signal into a digital signal.

The reference voltage generating circuit of the analog-to-digital converter sets ground, and when a positive power is applied, a positive reference voltage (+ Vref) and a negative reference voltage (-Vref) are output based on the ground.

Figure 1 shows a positive voltage reference voltage generator circuit of a conventional analog-to-digital converter.

As shown in FIG. 1, the positive voltage reference voltage generation circuit of the analog-to-digital converter includes a bandgap reference voltage generator 10, a negative reference voltage generator 20, and a positive reference voltage generator 30. have.

The bandgap reference voltage generator 10 receives the first power supply voltage VCC and the second power supply voltage VEE from the outside and outputs a bandgap reference voltage Vbg. The bandgap reference voltage generator 10 is disposed between the first power supply terminal 1 to which the first power supply voltage VCC is applied and the second power supply terminal 2 to which the second power supply voltage VEE is applied. Connected.

The negative reference voltage generator 20 receives the bandgap reference voltage Vbg and the ground voltage GROUND to output a negative reference voltage -Vref. The negative reference voltage generator 20 has a non-inverting ground connected to a first resistor R11 to which one end of the bandgap reference voltage Vbg is applied and an inverting terminal connected to the other end of the first resistor R11. And an operational amplifier including a terminal and a second resistor (R12) connected between the inverting terminal and an output terminal on which a negative reference voltage (-Vref) is output.

The positive reference voltage generator 30 receives the negative reference voltage (-Vref) and the ground voltage (GROUND) to output a positive reference voltage (+ Vref). The positive reference voltage generator 30 has a non-inverting ground connected to a third resistor R13 receiving one of the negative reference voltages -Vref and an inverting terminal connected to the other end of the third resistor R13. An operational amplifier including a terminal and a fourth resistor (R14) connected between the inverting terminal and the output terminal to which the positive reference voltage (+ Vref) is output.

Referring to FIG. 1, a reference voltage generation circuit of a positive power supply of a conventional analog-to-digital converter is as follows.

The first resistor R11, the second resistor R12, the third resistor R13 and the fourth resistor of the positive reference voltage generator 20 and the negative reference voltage generator 30 of the positive power reference voltage generator circuit ( R14) have the same resistance value.

The bandgap reference voltage generator 10 applies a VCC voltage to the first power supply terminal 1 to which the first power supply voltage is applied, and applies a VEE voltage to the second power supply terminal 2 to which the second power supply voltage is applied. When applied, the bandgap reference voltage Vbg is output.

The bandgap reference voltage generator 10 outputs a stable reference voltage at a constant level without being affected when the power supply voltage applied from the outside rises or falls or when the temperature changes rapidly.

The negative reference voltage generator 20 receives the bandgap reference voltage Vbg and the ground voltage GROUND to output a negative reference voltage -Vref. Since the negative reference voltage generator 10 is an inverted operational amplifier having the same value as the first resistor R11 and the second resistor R12, the negative reference voltage Vbg is input to receive the negative reference voltage of −Vbg. Vref) outputs. The positive reference voltage generator 30 receives a negative reference voltage (−Vref) of −Vbg to output a positive reference voltage (+ Vref). Since the positive reference voltage generator 30 is an inverted operational amplifier having the same value as the third resistor R13 and the fourth resistor R14, the positive reference voltage generator 30 receives a negative reference voltage (-Vref) of the -Vbg value to generate a positive Vbg value. Output the reference voltage (+ Vref).

As described above, a sufficient reference voltage can be obtained by applying a positive power supply to the reference voltage generating circuit of the analog-to-digital converter and designing a negative reference voltage (-Vref) and a positive reference voltage (+ Vref) based on the ground. . The negative reference voltage -Vref and the positive reference voltage + Vref generate a positive reference voltage level above the ground and a negative reference voltage level below the ground. If + 5V is applied to the first power supply terminal 1 and -5V is applied to the second power supply terminal 2, the reference voltage generating circuit generates a positive reference voltage of + 5V upward relative to ground, and ground Below, a reference voltage of -5V occurs.

However, according to the positive power supply voltage generator circuit of the conventional analog-to-digital converter as described above, there is a trouble of setting the ground and separately supplying the two power supply voltages from the outside. When the two power supplies are separately applied to the reference voltage generating circuit, the voltage supply path of the voltage supply unit is somewhat complicated.

Therefore, an object of the present invention has been proposed to solve the above-mentioned problems, it is necessary to apply only a single power supply to the reference voltage generator circuit of the analog-digital converter instead of the positive power supply to shorten the voltage path of the voltage supply and to set the ground separately. To provide a reference voltage generator circuit of the analog-to-digital converter.

1 is a reference circuit for generating a positive voltage source of an analog-to-digital converter according to the related art.

2 is a single power supply reference voltage generation circuit of an analog-to-digital converter according to the present invention;

Explanation of symbols for the main parts of the drawings

10: band gap reference voltage generator 20: negative reference voltage generator

30: both reference voltage generator 40: the first reference voltage generator

50: second reference voltage generator 60: third reference voltage generator

According to one aspect of the present invention for achieving the above object, a single power supply reference voltage generation circuit of an analog-to-digital converter includes a first reference voltage generator, a second reference voltage generator, and a third reference voltage generator. It contains wealth.

In a preferred embodiment of this circuit, the first reference voltage generator includes a first resistor and a second resistor connected in series between a power supply terminal and a ground terminal.

In a preferred embodiment of this circuit, the second reference voltage generator includes a bandgap reference voltage generator, a third resistor, a fourth resistor, and an operational amplifier.

In a preferred embodiment of this circuit, the third reference voltage generator includes a fifth resistor, a sixth resistor, and an operational amplifier.

By such a circuit, it is possible to implement a single power supply reference voltage generator of an analog-to-digital converter that generates a positive reference voltage (+ Vref) and a negative reference voltage (-Vref) when a power supply voltage is applied from the outside.

Hereinafter, the present invention will be described in detail with reference to FIG. 2.

2 shows a positive power supply reference voltage generator circuit of an analog-to-converter.

The reference voltage generator circuit of the analog-to-digital converter shown in FIG. 2 includes a first reference voltage generator 40, a second reference voltage generator 50, and a third reference voltage generator 60. .

The first resistor R1, the second resistor R2, and the third resistor of the first reference voltage generator 40, the second reference voltage generator 50, and the third reference voltage generator 60. The fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 have the same resistance value.

The first reference voltage generator 40 receives the power supply voltage VCC from the outside and outputs the first reference voltage VC. The first reference voltage generator 40 includes a first resistor R1 and a second resistor R2 connected in series between a power supply terminal 1 and a ground terminal 3 to which a power supply voltage VCC is applied. have.

The second reference voltage generator 50 receives the first reference voltage VC and outputs a second reference voltage + Vref. The second reference voltage generator 50 has a third resistor R3 having one end applied with the first reference voltage VC and a voltage VB lowered by a predetermined level by receiving the first reference voltage VC. Comprising a band gap reference voltage generator 10 for outputting a, a reverse terminal connected to the other end of the third resistor (R3) and a non-inverting terminal connected to the output terminal of the band gap reference voltage generator 10 An amplifier OP AMP and a fourth resistor R4 connected between the inverting terminal and the output terminal.

The third reference voltage generator 60 receives the first reference voltage VC and the second reference voltage + Verf and outputs a third reference voltage -Vref. The third reference voltage generator 60 may include a fifth resistor R5 to which one end is applied the second reference voltage (+ Vref), an inverting terminal connected to the other end of the fifth resistor R5, and the third resistor. An operational amplifier OP AMP including a non-inverting terminal receiving a first reference voltage VC and a sixth resistor R6 connected between the inverting terminal and the output terminal.

The operation of the single power supply reference voltage generation circuit of the analog-digital converter according to the present invention will be described in detail with reference to FIG. 2 as follows.

Since the first reference voltage generator 40 of the reference voltage generator shown in FIG. 2 receives the power supply voltage VCC from the outside, the values of the first resistor R1 and the second resistor R2 are the same. The voltage is output as the first reference voltage VC.

The second reference voltage generator 50 receives the first reference voltage VC to generate a second reference voltage (+ Vref). In the second reference voltage generator 50, the bandgap reference voltage generator 10 generates a bandgap reference voltage Vbg of VB-VC. When the first reference voltage VC is applied, the second reference voltage generator 50 generates a second reference voltage + Vref by the following equation.

Equation 1a

, R3 = R4

+ Vref from Equation 1a is expressed by the following equation.

[Equation 1b]

Substituting Vbg = VB-VC into the above formula (1b) yields a second reference voltage (+ Vref) of + Verf = VB + Vbg.

The third reference voltage generator 60 outputs a third reference voltage -Vref when the first reference voltage VC and the second reference voltage + Vref are applied. A third reference voltage (-Vref) can be obtained by the following equation.

Equation 2a

, R5 = R6

From the Equation 2a, -Vref is represented by the following equation.

[Equation 2b]

Substituting the formula of + Vref = VB + Vbg into Equation (2b), a third reference voltage (-Vref) of -Vref = 2VC-VB-Vbg is output. It can be seen that the third reference voltage -Vref is generated based on the first reference voltage VC instead of the ground.

When the difference between the second reference voltage (+ Vref) and the third reference voltage (-Vref) is obtained, a value of + Vref-(-Vref) = 4Vbg is obtained. If 5V is applied to the first power supply terminal 1, the reference voltages are generated based on VCC / 2, that is, 2.5V. Therefore, it can be seen that when the analog signal is changed to a digital signal at a short power supply, the reference voltage is reduced by half than when the analog signal at a power supply is converted to a digital signal.

This is because the reference voltage output from the ground of the conventional analog-to-digital converter of the reference voltage generator circuit has an absolute value, whereas the reference voltages of the reference voltage generator circuit of the single power supply are generated by the above equations. To convert analog signals to digital signals.

As described above, by reducing the power supply in the conventional positive power supply applied to the reference voltage generating circuit of the analog-to-digital converter, the voltage supply path of the power supply voltage supply unit is reduced, and the reference voltage of the analog-to-digital converter is generated even with a single power supply. have.

Claims (4)

A first reference voltage generator 40 receiving a power supply voltage VCC from the outside and outputting a first reference voltage VC; A second reference voltage generator 50 receiving the first reference voltage VC and outputting a second reference voltage + Vref; And a third reference voltage generator (50) for receiving the first reference voltage (VC) and the second reference voltage (+ Vref) and outputting a third reference voltage (-Vref). The first reference voltage generator 40 includes a first resistor R1 connected in series between a power supply terminal 1 and a ground terminal 3 to which a power supply voltage VCC is applied from the outside. A reference voltage generation circuit comprising a second resistor (R2). The method of claim 1, wherein the second reference voltage generator 50 comprises: a third resistor (R3), one end of which is applied with the second reference voltage (+ Vref); A bandgap reference voltage generator 10 receiving the first reference voltage VC at an input terminal; An operational amplifier (OP AMP) including an inverting terminal connected to the other end of the third resistor R3 and a non-inverting terminal connected to an output terminal of the bandgap reference voltage generator 10; And a fourth resistor (R4) connected between the inverting terminal and the output terminal. The third reference voltage generator (60) of claim 1, further comprising: a fifth resistor (R5) having one end applied with the second reference voltage (+ Vref); An operational amplifier (OP AMP) including an inverting terminal connected to the other end of the fifth resistor R5 and a non-inverting terminal to which the first reference voltage VC is applied; And a sixth resistor (R6) connected between the inverting terminal and the output terminal.