TWI409610B - Temperature coefficient modulating circuit and temperature compensation circuit - Google Patents

Abstract

The temperature compensation circuit uses thermal resistor to correct the detecting signal, but the compensation range is limited due to the thermal resistor. The present invention discloses a programmable temperature coefficient circuit that amplifies the temperature coefficient of the thermal resistor, so as to provide wider compensation range for wider range of application conditions.

Description

Temperature coefficient adjustment circuit and temperature compensation circuit

The invention relates to a temperature coefficient adjusting circuit and a temperature compensating circuit, in particular to a temperature coefficient adjusting circuit and a temperature compensating circuit which can improve the temperature coefficient.

The characteristics of electronic components vary depending on the operating temperature. In order to avoid temperature changes affecting the performance of electronic components, temperature compensation is generally used to correct the effects of temperature changes. The most common reference component for temperature compensation is the thermistor, which uses the characteristic that the resistance value of the thermistor changes with temperature to correct the variation of the characteristics of the electronic component with temperature, so that the performance temperature of the electronic component does not change with temperature. .

Since the thermistor itself can provide a limited temperature coefficient range, it is not suitable for applications that require a large temperature coefficient value as a temperature compensation reference. In the case where such a large temperature coefficient value is required for temperature compensation, the conventional technique uses a temperature compensation circuit as shown in the first figure to increase a large temperature coefficient value. The temperature compensation circuit shown in the first figure comprises a current source IDC, a thermistor RNTC, an analog-to-digital converter A/D and an adjustment current source IC. The current source IDC provides a steady current that does not change with temperature and flows through the thermistor RNTC, and the thermistor RNTC is a resistor having a negative temperature coefficient resistance value. Therefore, when the temperature rises, the voltage across the thermistor RNTC drops. The analog-to-digital converter A/D detects the voltage change across the thermistor RNTC and converts it into a digital control signal to control the output current IOUT_TC of the current source IC so that the output current IOUT_TC changes with temperature. The ratio of the voltage across the thermistor RNTC is amplified by the analog digital converter A/D to adjust the current change of the output current IOUT_TC of the current source IC, so that a temperature coefficient larger than the temperature coefficient value of the thermistor itself can be obtained. .

However, the use of an analog-to-digital converter not only increases the circuit area of the circuit, but also increases the circuit cost, and also increases the complexity of the circuit. In addition, the accuracy of the temperature coefficient is also affected by the A/D accuracy.

In view of the high cost and complicated circuit of the temperature compensation circuit in the prior art, the present invention uses one or more coefficient adjustment circuits to increase the temperature coefficient compensation value, so that the temperature coefficient can be amplified according to the application environment, and the temperature coefficient adjustment circuit can be simplified. The analog amplifier is achieved, so the circuit is simple in construction, accurate in temperature coefficient and low in cost.

To achieve the above object, the present invention provides a temperature coefficient adjustment circuit including a first coefficient adjustment circuit, a resistor, and a second coefficient adjustment circuit. The first coefficient adjustment circuit has a first temperature coefficient, and the first coefficient adjustment circuit receives an input signal and outputs a first current according to the input signal and the first temperature coefficient. The resistor has a first opposite temperature coefficient and the first opposite temperature coefficient and the first temperature coefficient are different numbers, and the resistor is coupled to the first coefficient adjusting circuit to generate a first voltage according to the first current. The second coefficient adjustment circuit has a second temperature coefficient component and the second temperature coefficient component has a second temperature coefficient, and the second coefficient adjustment circuit receives the first voltage and outputs a second current according to the first voltage and the second temperature coefficient, The first temperature coefficient and the second temperature coefficient are the same number.

The invention also provides a temperature compensation circuit comprising a detection circuit, a resistor and a coefficient adjustment circuit. The detecting circuit has a first temperature coefficient and is coupled to a unit to be tested to output a first current, wherein the temperature coefficient of the unit to be tested and the first temperature coefficient are the same number. The resistor has a first opposite temperature coefficient and the first opposite temperature coefficient and the first temperature coefficient are different numbers, and the resistor is coupled to the detecting circuit to generate a first voltage according to the first current. The coefficient adjustment circuit has a second temperature coefficient, and the coefficient adjustment circuit receives the first voltage and outputs a second current according to the first voltage and the second temperature coefficient, wherein the first temperature coefficient and the second temperature coefficient are the same number.

The above summary and the following detailed description are exemplary in order to further illustrate the scope of the claims. Other objects and advantages of the present invention will be described in the following description and drawings.

Referring to the second figure, there is shown a circuit diagram of a temperature coefficient adjusting circuit according to a first embodiment of the present invention. The temperature coefficient adjustment circuit includes a coefficient adjustment circuit TCB and a current mirror circuit CM. The coefficient adjustment circuit TCB includes a first thermistor RP, an amplifier EA, a transistor M, and a second thermistor RN, wherein the first thermistor RP has a positive temperature coefficient and the second thermistor RN Has a negative temperature coefficient. The coefficient adjustment circuit TCB receives an input signal ITC, which in this embodiment is a current signal, generates a voltage across the first thermistor RP and inputs the non-inverting input of the amplifier EA. The transistor M has a first end, a second end and a control end. The first end provides an amplification current ITC', and the second end is connected to the second thermistor RN to generate a signal to the inverting input of the amplifier EA. . The output of the amplifier EA The control terminal of the transistor M is connected. Since the amplifier EA and the transistor M form a voltage follower, the voltages of the inverting input and the non-inverting input of the amplifier EA are the same, so that: Itc*Rp=Itc'*Rn; where Itc is the input The current magnitude of the signal ITC, Itc' is the current magnitude of the amplification current ITC', Rp is the resistance value of the first thermistor RP, and Rn is the resistance value of the second thermistor RN.

The above formula can be rewritten as: Itc’=Itc*(Rp/Rn)

Therefore, the current of the input signal ITC is amplified to the amplification current ITC' at the ratio of (Rp/Rn). In this embodiment, the resistance value Rn of the second thermistor RN has a negative temperature coefficient (<1), and thus decreases as the temperature rises, and the resistance value Rn of the first thermistor RP has a positive temperature coefficient ( >1), so (Rp/Rn) will have a higher temperature coefficient than Rp and achieve the effect of amplifying the temperature coefficient.

Since the current direction of the amplification current ITC' is the inflow coefficient adjustment circuit TCB, for some applications requiring the current direction to flow out, the current mirror circuit CM can be connected as in the present embodiment to provide a current direction as an output current signal IBPTC. . The two P-type MOS field-effect transistors constituting the current mirror circuit CM have a channel width to length ratio of 1:N, so that the supplied current can be further adjusted to match different current demands.

The input signal ITC can be a detection signal or a signal that does not change with temperature. If it is a detection signal, the temperature coefficient adjustment circuit of the present invention can compensate for the temperature influence of the detection signal, so that the output current signal IBPTC can represent the detection result that is not affected by the temperature. If the input signal ITC is a signal that does not change with temperature, the output current signal IBPTC is a signal that changes with temperature, and can provide a reference for other circuits to change according to temperature. These applications can be referred to other embodiments described below.

Referring to the third figure, there is shown a circuit diagram of a temperature coefficient adjusting circuit according to a second embodiment of the present invention. The temperature coefficient adjustment circuit includes a bandgap reference circuit VBG, a coefficient adjustment circuit TCB, and a current mirror circuit CM. This embodiment differs from the embodiment shown in the second figure in the coefficient adjustment circuit TCB. The coefficient adjustment circuit TCB includes a dual carrier transistor BJT and a temperature coefficient element Rtc. The bandgap voltage reference circuit VBG provides a stable voltage signal that does not vary with temperature to the base of the bipolar transistor BJT. The emitter of the bipolar transistor BJT is coupled to the temperature coefficient element Rtc. The temperature coefficient element Rtc can be a negative temperature coefficient thermistor. The on-voltage Vbe of the bipolar transistor BJT has a negative temperature coefficient, so when the temperature rises, the voltage across the temperature coefficient element Rtc rises, so that the slope of the current flowing through the temperature coefficient element Rtc rises with temperature (ie, the temperature coefficient). The slope caused by the temperature coefficient element Rtc alone is also large. Therefore, the current supplied by the bipolar transistor BJT, that is, the temperature coefficient of the current flowing through the temperature coefficient element Rtc is amplified, and an output current signal IBPTC is generated after passing through the current mirror circuit CM.

Next, please refer to the fourth figure, which is a circuit diagram of a temperature coefficient adjusting circuit according to a third embodiment of the present invention. The temperature coefficient adjustment circuit includes a first coefficient adjustment circuit TCB1, a resistor RP1, a second coefficient adjustment circuit TCB2, a first current mirror circuit CM1, and a second current mirror circuit CM2. The first coefficient adjustment circuit TCB1 has a first temperature coefficient component. In this embodiment, a first negative temperature coefficient thermistor RN0 and a second negative temperature coefficient thermistor RN1 are connected in series. The first coefficient adjustment circuit TCB1 includes a voltage follower composed of an amplifier and a transistor to receive the input signal Vbg generated by a bandgap voltage reference circuit VBG, so that the voltage across the first temperature coefficient component is equal to the input. The voltage of the signal Vbg, wherein the voltage of the input signal Vbg is a stable voltage that does not change with temperature. See the description of the second figure for a description of the voltage follower. Therefore, the first temperature coefficient component and the transistor will flow through a first current ITC1, and the current magnitude is the voltage across the first temperature coefficient component divided by the resistance value of the first temperature coefficient component, so the first current ITC1 has a positive Temperature Coefficient.

The first current mirror circuit CM1 is coupled between the first coefficient adjustment circuit TCB1 and the resistor RP1 to proportionally amplify the first current ITC1 into an amplification current ITC2 to be supplied to the resistor RP1. In this embodiment, the temperature coefficient of the resistor RP1 and the temperature coefficient of the first temperature coefficient component in the first coefficient adjustment circuit TCB1 are different numbers, that is, when the temperature coefficient of the resistor RP1 is a positive temperature coefficient, the first temperature The temperature coefficient of the coefficient element is a negative temperature coefficient, and vice versa. In the present embodiment, the resistor RP1 has a positive temperature coefficient. Therefore, the temperature signal generated by the amplification current ITC2 flowing through the resistor RP1 will be further improved. The circuit structure of the second coefficient adjustment circuit TCB2 is similar to that of the first coefficient adjustment circuit TCB1, and includes a voltage follower composed of an amplifier and a transistor and a second temperature coefficient element RN2, and the second temperature coefficient element RN2 in this embodiment. The thermistor with a negative temperature coefficient has the same temperature coefficient as the temperature coefficient of the first temperature coefficient component. Therefore, the temperature coefficient of the voltage signal generated by the resistor RP1 is again increased, and is amplified by the second current mirror circuit CM2 to output an output current signal IBPTC.

Compared with the foregoing two embodiments, the embodiment shown in the fourth embodiment has more resistance RP1 and second coefficient adjustment circuit TCB2 to improve the temperature coefficient, so the temperature coefficient lifting effect of the embodiment is more obvious.

Referring to FIG. 5, a circuit block diagram of a temperature coefficient adjusting circuit according to a fourth embodiment of the present invention. The input signal ITC0 is multiplied by the first coefficient adjustment circuit ITCB1, the first resistor Rt1, the second coefficient adjustment circuit ITCB2, the second resistor Rt2, ..., the nth coefficient adjustment circuit ITCBn, and the nth resistor Rtn to become an output signal. ITCn. The first coefficient adjustment circuit ITCB1, the second coefficient adjustment circuit ITCB2, ..., the nth coefficient adjustment circuit ITCBn may be the coefficient adjustment circuit in the above embodiment, and the temperature coefficient adjustment amount of each coefficient adjustment circuit (ie, the output The signal/received signal) are all the same number. In addition, the first resistor Rt1, the second resistor Rt2, ..., and the nth resistor Rtn may be determined whether the output signal is a voltage or a current or a signal type that can be processed by a circuit of a subsequent stage. As shown in the second to fourth figures, the coefficient adjustment circuit is an input voltage signal and outputs a current signal. Therefore, the output current signal is converted into a voltage signal through the conversion of the resistors Rt1 to Rtn.

Referring again to the sixth figure, there is shown a circuit diagram of a temperature compensation circuit according to the present invention. The temperature compensation circuit includes a detection circuit DET, a resistor Rtc2, and a coefficient adjustment circuit TCB3. The detection circuit DET has a first temperature coefficient component Rtc1, and is coupled to a device under test DUT through the first detection terminal D1 and the second detection terminal D2 to output a first current IDE. In this embodiment, the first detecting end D1 and the second detecting end D2 are two input ends of the amplifier in the detecting circuit DET. The temperature coefficient of the first temperature coefficient component Rtc1 is the same as the temperature coefficient of the unit to be tested, and the temperature coefficient of the resistor Rtc2 is an opposite sign, in order to compensate for the change in the voltage Vde caused by the temperature change of the DUT to be tested. number. The first current IDE is amplified by a first current mirror circuit CM1 to be an amplification current ITCC1 and then input to a resistor Rtc2 to generate a voltage signal input coefficient adjustment circuit TCB3. The coefficient adjustment circuit TCB3 has a third temperature coefficient element Rtc3 which is a temperature coefficient of the same number as the first temperature coefficient element Rtc1, and outputs a current according to the voltage signal and its own temperature coefficient, and passes through a second current mirror circuit. The CM2 ratio is amplified to an amplified current ITCC2 output.

The DUT to be tested may be a detecting resistor (for example, a feedback detecting resistor used in a circuit for feedback control), an on-resistance of a MOS field-effect transistor, a light-emitting diode or the like. Electronic components that change the performance of a feature are even circuits. The equivalent temperature coefficient of the temperature compensating circuit of the present invention can be changed by adjusting the temperature coefficient of the coefficient adjusting circuit and the thermistor so as to be the reciprocal of the temperature coefficient of the DUT of the unit to be tested, thereby obtaining compensation and compensation. Temperature independent of a signal output.

Since the temperature coefficient adjustment of the present invention is achieved by simple analog circuits and components such as amplifiers, thermistors, and transistors, the circuit configuration is relatively simple and the cost is relatively low, and the adjustment coefficient adjustment circuit can be adjusted depending on the application environment. The number or temperature coefficient is obtained to meet the required temperature compensation effect.

As described above, the present invention fully complies with the three requirements of the patent: novelty, advancement, and industrial applicability. The invention has been described above in terms of the preferred embodiments, and it should be understood by those skilled in the art that the present invention is not intended to limit the scope of the invention. It should be noted that variations and permutations equivalent to those of the embodiments are intended to be included within the scope of the present invention. Therefore, the scope of the invention is defined by the scope of the following claims.

Prior art:

IDC‧‧‧current source

RNTC‧‧‧Thermistor

A/D‧‧‧ analog digital converter

IC‧‧‧Adjust current source

IOUT_TC‧‧‧Output current

this invention:

RP, RN‧‧‧ thermistor

EA‧‧Amplifier

M‧‧‧O crystal

ITC, Vbg, ITC0‧‧‧ input signals

ITC’, ITC2, ITCC1, ITCC2‧‧‧Amplify current

IBPTC‧‧‧ output current signal

VBG‧‧‧gap voltage reference circuit

BJT‧‧‧ double carrier transistor

Rtc, Rtc1, Rtc3‧‧‧ temperature coefficient components

Vbe‧‧‧ turn-on voltage

TCB, TCB1, TCB2, TCB3, ITCB1, ITCB2, ITCBn‧‧‧ coefficient adjustment circuit

RP1, Rtc2, Rt1, Rt2, Rtn‧‧‧ resistor

CM, CM1, CM2‧‧‧ current mirror circuit

RNO, RN1, RN2‧‧‧negative temperature coefficient thermistor

ITCn‧‧‧ output signal

DET‧‧‧Detection Circuit

D1, D2‧‧‧Detection

DUT‧‧‧ unit to be tested

IDE‧‧‧ Current

ITC1‧‧‧First current

Vde‧‧‧cross pressure

Vbe‧‧‧ turn-on voltage

The first figure is a schematic circuit diagram of a conventional temperature compensation circuit.

The second figure is a circuit diagram of a temperature coefficient adjustment circuit according to a first embodiment of the present invention.

The third figure is a circuit diagram of a temperature coefficient adjustment circuit according to a second embodiment of the present invention.

The fourth figure is a circuit diagram of a temperature coefficient adjusting circuit according to a third embodiment of the present invention.

Figure 5 is a circuit block diagram of a temperature coefficient adjustment circuit in accordance with a fourth embodiment of the present invention.

Figure 6 is a circuit diagram of a temperature compensation circuit in accordance with the present invention.

TCB1. . . First coefficient adjustment circuit

RP1. . . resistance

TCB2. . . Second coefficient adjustment circuit

CM1. . . First current mirror circuit

CM2. . . Second current mirror circuit

RN0, RN1, RN2. . . Negative temperature coefficient thermistor

VBG. . . Bandgap voltage reference circuit

Vbg. . . Input signal

IBPTC. . . Output current signal

Claims (14)

A temperature coefficient adjustment circuit includes: a first coefficient adjustment circuit having a first temperature coefficient, the first coefficient adjustment circuit receiving an input signal and outputting a first current according to the input signal and the first temperature coefficient; The first resistor has a first opposite temperature coefficient and the first opposite temperature coefficient and the first temperature coefficient are different numbers, and the first resistor is coupled to the first coefficient adjusting circuit to generate a first according to the first current a first voltage; and a second coefficient adjustment circuit having a second temperature coefficient element and the second temperature coefficient element having a second temperature coefficient, the second coefficient adjustment circuit receiving the first voltage and according to the first voltage And the second temperature coefficient outputs a second current, wherein the first temperature coefficient and the second temperature coefficient are the same number, and the ratio of the first temperature coefficient to the second temperature coefficient is greater than 1. The temperature coefficient adjustment circuit of claim 1, wherein the first coefficient adjustment circuit comprises: a first amplifier having a first input end, a second input end, and a first output end, the first An input terminal receives the input signal; a first transistor having a first end, a second end, and a first control terminal and providing the first current; and a first temperature coefficient component having a first temperature a coefficient of resistance, the first temperature coefficient is coupled to the second end of the first transistor to generate a first temperature coefficient adjustment signal according to the first current to the second input end of the first amplifier; wherein The first amplifier outputs a first control signal to the first control end of the first transistor according to the input signal and the first temperature coefficient adjustment signal to adjust the first current. The temperature coefficient adjustment circuit of claim 1, further comprising a first current mirror circuit coupled to the first coefficient adjustment circuit Between the circuit and the first resistor, and proportionally amplifying the first current to be supplied to the first resistor. The temperature coefficient adjustment circuit according to claim 3, further comprising: a second resistor having a second opposite temperature coefficient and the second opposite temperature coefficient and the second temperature coefficient being different numbers, the first a second resistor coupled to the second coefficient adjusting circuit to generate a second voltage according to the second current; and a third coefficient adjusting circuit having a third temperature coefficient element and the third temperature coefficient element having a third temperature a third coefficient adjustment circuit receives the second voltage and outputs a third current according to the second voltage and the third temperature coefficient, wherein the second temperature coefficient and the third temperature coefficient are the same number. The temperature coefficient adjustment circuit of claim 4, further comprising a second current mirror circuit coupled between the second coefficient adjustment circuit and the second resistor to scale up The second current is a second amplified current. The temperature coefficient adjustment circuit of claim 3, wherein the second coefficient adjustment circuit comprises: a second amplifier having a third input end, a fourth input end, and a second output end, the The third input terminal receives the first voltage; a second transistor having a third end, a fourth end, and a second control end and providing the second current; and the second temperature coefficient component having a second a temperature coefficient resistance, the second temperature coefficient is coupled to the fourth end of the second transistor to generate a second temperature coefficient adjustment signal according to the second current to the fourth input end of the second amplifier; The second amplifier adjusts a signal according to the first voltage and the second temperature coefficient to output a second control signal to the second control end of the second transistor to adjust the second current. The temperature coefficient adjustment circuit of claim 1, wherein the first coefficient adjustment circuit comprises: a dual carrier transistor having a base, an emitter and a collector, the base receiving the input The signal provides the first current at the collector; and a first temperature coefficient component coupled to the emitter of the bipolar transistor. A temperature compensation circuit includes: a detection circuit having a first temperature coefficient coupled to a unit to be tested to output a first current, wherein a temperature coefficient of the unit to be tested and the first temperature coefficient are the same number a first resistor having a first opposite temperature coefficient and the first opposite temperature coefficient and the first temperature coefficient being an odd number, the first resistor coupled to the detecting circuit to generate a a first voltage; and a coefficient adjustment circuit having a second temperature coefficient, the coefficient adjustment circuit receiving the first voltage and outputting a second current according to the first voltage and the second temperature coefficient, wherein the first temperature coefficient And the second temperature coefficient is the same number. The temperature compensation circuit of claim 8, wherein the detection circuit comprises: a first amplifier having a first input end, a second input end, and a first output end, the first input end The first transistor has a first end, a second end, and a first control end and provides the first current; and a first temperature coefficient component coupled to the first The second end of the transistor and the other end of the unit to be tested generate a first temperature coefficient adjustment signal according to the first current to the second input end of the first amplifier to adjust the first current. The temperature compensation circuit of claim 8, further comprising a first current mirror circuit coupled to the detection circuit and the first The first current is proportionally amplified and supplied to the first resistor. The temperature compensation circuit of claim 10, further comprising a second resistor having a second opposite temperature coefficient and the second temperature coefficient and the second temperature coefficient being different numbers, the second resistor The coefficient adjustment circuit is coupled to generate a second voltage according to the second current. The temperature compensation circuit of claim 11, further comprising a second current mirror circuit coupled between the coefficient adjustment circuit and the second resistor to scale up the second The current is a second amplified current. The temperature compensation circuit of claim 10, wherein the coefficient adjustment circuit comprises: a second amplifier having a third input terminal, a fourth input terminal and a second output terminal, the third input terminal Receiving the first voltage; a second transistor having a third end, a fourth end, and a second control end and providing the second current; and the second temperature coefficient component having a second temperature coefficient resistor The second temperature coefficient is coupled to the fourth end of the second transistor to generate a second temperature coefficient adjustment signal according to the second current to the fourth input end of the second amplifier; wherein the second The amplifier adjusts a signal according to the first voltage and the second temperature coefficient to output a second control signal to the second control end of the second transistor to adjust the second current. The temperature compensation circuit of claim 8, wherein the detection circuit comprises: a dual carrier transistor having a base, an emitter and a collector, the base being coupled to the unit to be tested One end of the first current is provided at the collector; and a first temperature coefficient element coupled to the emitter of the bipolar transistor and the The other end of the unit to be tested.