Temperature voltage frequency conversion hybrid integrated circuit

Abstract

The invention discloses a temperature voltage frequency conversion hybrid integrated circuit, and belongs to the technical field of signal processing. The circuit comprises a temperature detection circuit, a voltage reference circuit, a differential amplification circuit, an integrator circuit, a comparator circuit, a trigger circuit, an electronic switch circuit and a constant current source circuit. The output ends of the temperature detection circuit and the voltage reference circuit are connected with the non-inverting input end and the inverting input end of the differential amplification circuit; the differential amplification circuit, the integrator circuit, the comparator circuit and the trigger circuit are sequentially connected in series; the output end of the trigger circuit and the input end of the integrator circuit form a closed loop through the electronic switch circuit; the constant current source circuit is connected with the input end of the integrator circuit through the electronic switch circuit. The temperature, voltage and frequency conversion hybrid integrated circuit provided by the invention can flexibly set a temperature demarcation point, and is high in conversion accuracy, strong in anti-interference capability, small in size and strong in universality.

Description

Technical Field

[0001] The invention belongs to the technical field of signal processing and relates to a temperature-voltage-frequency conversion hybrid integrated circuit. Background Art

[0002] The temperature voltage to frequency conversion circuit converts the induced temperature signal into a counting pulse signal. The frequency of the counting pulse is proportional to the size of the temperature signal. This technology is widely used in the fields of temperature measurement and control, data acquisition and communication systems. However, the temperature voltage to frequency conversion circuit in the prior art has problems such as poor anti-interference ability, small temperature measurement range and low accuracy. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a temperature-voltage-frequency conversion hybrid integrated circuit with high accuracy, strong anti-interference capability and small size.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] The present invention provides a temperature-voltage-frequency conversion hybrid integrated circuit, comprising: a temperature detection circuit, a voltage reference circuit, a differential amplifier circuit, an integrator circuit, a comparator circuit, a trigger circuit, an electronic switch circuit and a constant current source circuit;

[0006] The output end of the temperature detection circuit is connected to the non-inverting input end of the differential amplifier circuit;

[0007] The output end of the voltage reference circuit is connected to the inverting input end of the differential amplifier circuit;

[0008] The differential amplifier circuit, the integrator circuit, the comparator circuit and the trigger circuit are connected in series in sequence;

[0009] The output end of the trigger circuit forms a closed loop with the input end of the integrator circuit through the electronic switch circuit;

[0010] The constant current source circuit is connected to the input end of the integrator circuit through the electronic switch circuit.

[0011] Furthermore, the temperature detection circuit includes a reference voltage source, a temperature sensor, a sampling resistor and an operational amplifier; the reference voltage source, the temperature sensor and the operational amplifier are connected in series in sequence, one end of the sampling resistor is connected between the temperature sensor and the operational amplifier, and the other end is grounded

[0012] Furthermore, the temperature detection circuit is used to collect the temperature signal T of the object to be measured and convert the collected temperature signal T into an electrical signal V 01 ; The voltage reference circuit is used to provide a reference voltage V 02 ;

[0013] When V 01 =V 02 When the output voltage of the differential amplifier circuit is V 03 =0, at this time the temperature of the object to be measured T=0℃;

[0014] When V 01 >V 02 When the output voltage of the differential amplifier circuit is V 03 >0, at this time the temperature of the object to be measured T>0℃;

[0015] When V 01 <V 02 When the output voltage of the differential amplifier circuit is V 03 <0, at this time the temperature of the object to be measured T<0℃.

[0016] Furthermore, the voltage reference circuit includes a reference voltage source ADR02, whose reference voltage V 02 =+5V.

[0017] Further, the differential amplifier circuit includes an instrumentation amplifier AD620;

[0018] A resistor is provided between the differential amplifier circuit and the integrator circuit to convert the output voltage V 03 After being converted into a current signal, it is input into the integrator circuit.

[0019] Further, the comparator circuit includes a first comparator circuit and a second comparator circuit; the trigger circuit includes a first trigger circuit and a second trigger circuit;

[0020] The output end of the first comparator circuit is connected to the input end of the first trigger circuit; the output end of the second comparator circuit is connected to the input end of the second trigger circuit.

[0021] Furthermore, it also includes a frequency division circuit and a clock;

[0022] The clock is respectively connected to the clock pulse input terminals of the first trigger circuit and the second trigger circuit through a frequency dividing circuit.

[0023] Furthermore, the frequency division circuit includes a dual D flip-flop.

[0024] Furthermore, when the differential amplifier circuit outputs a voltage V 03 =0, under the drive of the clock signal, the output frequency of the first trigger circuit and the second trigger circuit is 0;

[0025] When the differential amplifier circuit outputs a voltage V 03>0, under the drive of the clock signal, the first trigger circuit outputs the frequency signal FO+, and the second trigger circuit has no frequency output;

[0026] When the differential amplifier circuit outputs a voltage V 03 <0, under the drive of the clock signal, the second trigger circuit outputs the frequency signal FO-, and the first trigger circuit has no frequency output.

[0027] Further, the constant current source circuit is a positive and negative constant current source circuit, which is used to provide a reset current for the integrator circuit;

[0028] When the output frequency signal FO+ of the first trigger circuit is at a high level, the switch in the electronic switch circuit is turned on, and the current generated by the negative constant current source is connected to the integrator circuit;

[0029] When the output frequency signal FO- of the second trigger circuit is at a high level, the switch in the electronic switch circuit is turned on, and the current generated by the positive constant current source is connected to the integrator circuit.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The temperature-voltage-frequency conversion hybrid integrated circuit provided by the present invention has a temperature detection circuit capable of flexibly setting a temperature dividing point; a voltage-frequency conversion circuit composed of an integrator circuit, a comparator circuit, a trigger circuit, a frequency division circuit, a constant current source circuit and an electronic switch circuit has high resolution; a voltage reference circuit adopts a reference voltage source ADR02, has an operating temperature range of -55°C to 125°C, has high precision and good stability; a differential amplifier circuit adopts an instrument amplifier such as AD620, has an amplification factor of 1, does not require peripheral resistors, has good stability, and significantly improves the accuracy of the temperature-voltage-frequency conversion circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 2 is a schematic diagram of the structure of a temperature detection circuit in the prior art;

[0033] Figure 2 1 is a circuit schematic diagram of a temperature detection circuit in the prior art;

[0034] Figure 3 A schematic diagram of the structure of a temperature-voltage-frequency conversion hybrid integrated circuit provided by an embodiment of the present invention;

[0035] Figure 4 is a circuit schematic diagram of a temperature detection circuit in an embodiment of the present invention;

[0036] Figure 5 is a circuit schematic diagram of a voltage reference circuit in an embodiment of the present invention;

[0037] Figure 6is a circuit schematic diagram of a differential amplifier circuit in an embodiment of the present invention;

[0038] Figure 7 is a circuit schematic diagram of a frequency division circuit in an embodiment of the present invention;

[0039] Figure 8 is a circuit schematic diagram of positive and negative constant current sources in an embodiment of the present invention;

[0040] Fig. 9 4 is a circuit schematic diagram of a voltage-to-frequency conversion circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. The embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0042] The term "and / or" herein is only a description of the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " herein generally indicates that the front and back associated objects are in an "or" relationship. The orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, and is only used to explain the relative position relationship, movement, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure / application.

[0043] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0044] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0045] like Figure 1 and Figure 2 As shown in the figure, the patent number CN 101446494 A discloses a temperature detection circuit for a satellite-borne fiber optic gyroscope. The circuit includes a temperature sensor, a voltage reference, a temperature-voltage conversion circuit, a differential operational amplifier unit, an analog-to-digital conversion unit and a digital signal processing unit. It is a typical temperature detection circuit with the following disadvantages: 1) The voltage reference uses a three-terminal adjustable reference diode, and its temperature drift coefficient is 30ppm / ℃~150ppm / ℃. The drift of the peripheral resistors R1, R2, R3 and the follower amplifier U1B is superimposed. In the full temperature range, the temperature drift of the output reference voltage is large, the reference voltage is unstable, and the accuracy of the output voltage Vout of the error operational amplifier unit is reduced, so that the accuracy of the entire temperature measurement circuit is low; 2) The differential operational amplifier unit uses an ordinary in-phase proportional amplifier, and the error is large; 3) The entire circuit transmits voltage signals, and the key component of the analog-to-digital conversion unit uses an A / D converter, which has poor anti-interference ability; 4) The temperature measurement range is small, which is -20℃~55℃. Therefore, based on these shortcomings, the present invention designs a temperature-voltage-frequency conversion hybrid integrated circuit with high accuracy, strong anti-interference ability and small size.

[0046] like Figure 3 As shown, an embodiment of the present invention provides a temperature-voltage-frequency conversion hybrid integrated circuit, comprising: a temperature detection circuit, a voltage reference circuit, a differential amplifier circuit, an integrator circuit, a comparator circuit, a trigger circuit, an electronic switch circuit and a constant current source circuit;

[0047] The output end of the temperature detection circuit is connected to the in-phase input end of the differential amplifier circuit;

[0048] The output end of the voltage reference circuit is connected to the inverting input end of the differential amplifier circuit;

[0049] The differential amplifier circuit, the integrator circuit, the comparator circuit and the trigger circuit are connected in series in sequence;

[0050] The output end of the trigger circuit forms a closed loop with the input end of the integrator circuit through the electronic switch circuit;

[0051] The constant current source circuit is connected to the input end of the integrator circuit through the electronic switch circuit.

[0052] The temperature detection circuit is used to collect the temperature signal T of the object to be measured and convert the temperature signal T into an electrical signal V 01 .

[0053] like Figure 4 As shown, in an embodiment of the present invention, the temperature detection circuit includes a reference voltage source U1, a temperature sensor AD590, a sampling resistor R1 and an operational amplifier U2; the reference voltage source U1, the temperature sensor AD590 and the operational amplifier U2 are connected in series in sequence, one end of the sampling resistor R1 is connected to the connection path between the temperature sensor AD590 and the operational amplifier U2, and the other end is grounded.

[0054] The reference voltage source U1 provides the operating voltage for the temperature sensor AD590, and the operational amplifier U2 forms a voltage follower. As the temperature T of the object to be detected changes, the resistance value of the sampling resistor R1 changes accordingly. Correspondingly, the temperature detection circuit outputs a voltage V 01 And the temperature T of the object to be detected is related to the output voltage V of the temperature detection circuit. 01 There is a linear relationship.

[0055] The voltage reference circuit is used to provide a reference voltage V 02 .

[0056] like Figure 5 As shown, in the embodiment of the present invention, a reference voltage source ADR02 is used as a voltage reference circuit. The reference voltage V output by the reference voltage source ADR02 is 02 =+5V, output voltage temperature drift ≤3ppm / ℃, long-term stability typical value is 50ppm / 1000Hr, operating temperature range is -55℃~125℃, high precision and good stability.

[0057] Electrical signal V 01 and reference voltage V 02 They are respectively connected to the non-inverting input terminal and the inverting input terminal of the differential amplifier circuit for differential amplification.

[0058] The temperature detection circuit of the present invention can flexibly set the temperature demarcation point T0 (the corresponding demarcation point voltage is +5V). For example, the temperature demarcation point T0 is set to 0°C, at which time the conversion circuit output frequency is 0; when the temperature T of the object to be measured is greater than T0, the conversion circuit output frequency FO+; when the temperature T of the object to be measured is less than T0, the conversion circuit output frequency FO-, which can accurately determine the temperature demarcation point of the object.

[0059] The differential amplifier circuit is used to amplify the input voltage signal. Figure 6As shown, in the embodiment of the present invention, the differential amplifier circuit uses an instrument amplifier U4, specifically AD620U4, and its gain is:

[0060] ,

[0061] when When , G=1, that is, the gain is 1.

[0062] When V 01 >V 02 When V 01 <V 02 When , the output voltage of the differential amplifier circuit is negative.

[0063] Specifically, when V 01 =V 02 When the output voltage of the differential amplifier circuit is V 03 =0, then the temperature of the object to be measured is T=0℃; when V 01 >V 02 When the output voltage of the differential amplifier circuit is V 03 >0, then the temperature of the object to be measured T>0℃; when V 01 <V 02 When the output voltage of the differential amplifier circuit is V 03 <0, at this time the temperature of the object to be measured T<0℃.

[0064] A resistor is also provided on the connection path between the output end of the differential amplifier circuit and the input end of the integrator circuit to convert the output voltage V 03 After being converted into a current signal I, it is input into the integrator circuit.

[0065] The integrator circuit is used to obtain the current signal I and the reset current signal (IO+ or IO-) generated by the positive and negative constant current source circuits and perform integration processing.

[0066] As shown in Figure 1, the comparator circuit includes a first comparator circuit and a second comparator circuit; the trigger circuit includes a first trigger circuit and a second trigger circuit; the output end of the first comparator circuit is connected to the input end of the first trigger circuit; the output end of the second comparator circuit is connected to the input end of the second trigger circuit. The first comparator circuit and the second comparator circuit are used to obtain the output signal of the integrator circuit and compare it with its threshold voltage; the first trigger circuit is used to obtain the first comparator circuit and the clock signal and generate a pulse signal; the first trigger circuit is used to obtain the second comparator circuit and the clock signal and generate a pulse signal.

[0067] Correspondingly, the temperature-voltage-frequency conversion hybrid integrated circuit of the present invention further includes a frequency division circuit and a clock; the clock is respectively connected to the clock pulse input terminals of the first trigger circuit and the second trigger circuit through the frequency division circuit. The frequency division circuit is used to convert the high-frequency clock signal CLK0 into the clock signal CLK1 required by the first trigger circuit and the second trigger circuit, and drive the trigger circuit to output the frequency signal FO+ or FO-.

[0068] like Figure 7 As shown, in the embodiment of the present invention, the frequency division circuit uses a dual D flip-flop D1.

[0069] When the output voltage V 03 =0, the current signal I=0, and under the drive of the clock signal, the output frequency of the first trigger circuit and the second trigger circuit is 0;

[0070] When the output voltage V 03 >0, the current signal I>0, the current flows into the integrator circuit, and the first comparator circuit and the first trigger circuit start working. Driven by the clock signal, the first trigger circuit outputs the frequency signal FO+, and the second trigger circuit has no frequency output;

[0071] When the output voltage V 03 <0, the current signal I<0, the current flows out of the integrator circuit, at which time the second comparator circuit and the second trigger circuit start to work. Driven by the clock signal, the second trigger circuit outputs a frequency signal FO-, and the first trigger circuit has no frequency output.

[0072] The above process realizes the conversion from temperature to voltage and then to frequency.

[0073] The constant current source circuit of the present invention is a positive and negative constant current source circuit, which is used to provide a reset current for the integrator circuit. The positive and negative output frequencies are used as control signals of the electronic switch circuit to control the electronic switch to switch from an off state to an on state. After the electronic switch is turned on, the positive and negative constant current sources apply corresponding currents to the integrator circuit to control the discharge of the integrator circuit.

[0074] like Figure 8 As shown, in the embodiment of the present invention, the positive and negative constant current sources include a reference voltage source U5, a voltage follower U6, and a sampling resistor R5 and a sampling resistor R6 connected in series. The reference voltage output by the reference voltage source U5 passes through the voltage follower U6, and then passes through the sampling resistor R5 to generate a reset current IO+, or passes through the sampling resistor R6 to generate a reset current IO-, and the reset current discharges the integrator circuit through the electronic switch circuit.

[0075] When the output frequency signal FO+ of the first trigger circuit is at a high level, the switch in the electronic switch circuit is turned on, and the current generated by the negative constant current source is connected to the integrator circuit, so that the integrator is reset; when the output frequency signal FO- of the second trigger circuit is at a high level, the switch in the electronic switch circuit is turned on, and the current generated by the positive constant current source is connected to the integrator circuit, so that the integrator is reset.

[0076] like Fig. 9 As shown, the present invention forms a voltage-frequency conversion circuit by sequentially connecting an integrator, a dual-channel comparator, a dual-channel trigger and a four-channel analog switch in series. The circuit adopts the principle of a charge-balanced voltage-frequency conversion circuit. After the input voltage passes through the integrator, the integrator outputs a sawtooth wave output in the opposite direction with a bias voltage according to the polarity of the input. The comparator compares the corresponding comparison voltages respectively, outputs a sharp pulse signal with the same frequency as the sawtooth wave, and the sharp pulse signal passes through a dual D-type trigger to output a square wave signal with a pulse width the same as the period of the peripheral clock signal.

[0077] During the positive pulse period of the output frequency signal, the positive and negative constant current source signals are sent to the input of the integrator. Since the current signal (IO+ or IO-) generated by the constant current source is much larger than the input signal current I, the primary integrator enters the forced reset stage. The reset time is constant, while the charging time changes with the input, thus realizing voltage-controlled oscillation and completing the voltage-frequency conversion.

[0078] The voltage-frequency conversion circuit of the present invention has high resolution. When the temperature demarcation point T0 is set to 0°C, when the temperature changes from 0°C to 125°C, the output frequency FO+ changes from 0Hz to 100kHz, and its conversion equivalent is 125°C / 100000Hz=0.00125°C / Hz, that is, the resolution is 0.00125°C / Hz; when the temperature changes from 0°C to -55°C, the output frequency FO- changes from 0Hz to 44kHz, and its conversion equivalent is 125°C / 44000Hz=0.00125°C / Hz, that is, the resolution is 0.00125°C / Hz. Therefore, in the entire temperature range of -55°C to 125°C, the resolution of the voltage-frequency conversion circuit can reach 0.00125°C / Hz.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of this disclosure / application.

Claims

1. A temperature-voltage-frequency conversion hybrid integrated circuit, characterized in that: include: Temperature detection circuit, voltage reference circuit, differential amplifier circuit, integrator circuit, comparator circuit, trigger circuit, electronic switch circuit and constant current source circuit; The output end of the temperature detection circuit is connected to the non-inverting input end of the differential amplifier circuit; The output end of the voltage reference circuit is connected to the inverting input end of the differential amplifier circuit; The differential amplifier circuit, the integrator circuit, the comparator circuit and the trigger circuit are connected in series in sequence; The output end of the trigger circuit forms a closed loop with the input end of the integrator circuit through the electronic switch circuit; The constant current source circuit is connected to the input end of the integrator circuit through the electronic switch circuit.

2. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 1, characterized in that: The temperature detection circuit includes a reference voltage source, a temperature sensor, a sampling resistor and an operational amplifier; the reference voltage source, the temperature sensor and the operational amplifier are connected in series in sequence, one end of the sampling resistor is connected to the connection path between the temperature sensor and the operational amplifier, and the other end is grounded.

3. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 1, characterized in that: The temperature detection circuit is used to collect the temperature signal of the object to be measured and convert the collected temperature signal into an electrical signal V 01 ; The voltage reference circuit is used to provide a reference voltage V 02 ; When V 01 =V 02 When the output voltage of the differential amplifier circuit is V 03 =0, at this time the temperature of the object to be measured T=0℃; When V 01 >V 02 When the output voltage of the differential amplifier circuit is V 03 >0, at this time the temperature of the object to be measured T>0℃; When V 01 <V 02 When the output voltage of the differential amplifier circuit is V 03 <0, at this time the temperature of the object to be measured T<0℃.

4. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 3, characterized in that: The voltage reference circuit includes a reference voltage source ADR02, whose reference voltage V 02 =+5V.

5. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 3, characterized in that: The differential amplifier circuit includes an instrument amplifier AD620; A resistor is provided on the connection path between the differential amplifier circuit and the integrator circuit to convert the output voltage V 03 After being converted into a current signal, it is input into the integrator circuit.

6. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 3, characterized in that: The comparator circuit includes a first comparator circuit and a second comparator circuit; the trigger circuit includes a first trigger circuit and a second trigger circuit; The output end of the first comparator circuit is connected to the input end of the first trigger circuit; the output end of the second comparator circuit is connected to the input end of the second trigger circuit.

7. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 6, characterized in that: It also includes frequency division circuit and clock; The clock is respectively connected to the clock pulse input terminals of the first trigger circuit and the second trigger circuit through a frequency dividing circuit.

8. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 7, characterized in that: The frequency division circuit includes a dual-path D flip-flop.

9. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 8, characterized in that: When the output voltage V 03 =0, under the drive of the clock signal, the output frequency of the first trigger circuit and the second trigger circuit is 0; When the output voltage V 03 >0, under the drive of the clock signal, the first trigger circuit outputs the frequency signal FO+, and the second trigger circuit has no frequency output; When the differential amplifier circuit outputs a voltage V 03 <0, under the drive of the clock signal, the second trigger circuit outputs the frequency signal FO-, and the first trigger circuit has no frequency output.

10. The temperature-voltage-frequency conversion hybrid integrated circuit according to claim 8, characterized in that: The constant current source circuit is a positive and negative constant current source circuit, which is used to provide a reset current for the integrator circuit; When the output frequency signal FO+ of the first trigger circuit is at a high level, the switch in the electronic switch circuit is turned on, and the current generated by the negative constant current source is connected to the integrator circuit; When the output frequency signal FO- of the second trigger circuit is at a high level, the switch in the electronic switch circuit is turned on, and the current generated by the positive constant current source is connected to the integrator circuit.

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