CN105030254A - Optical frequency converting device with temperature compensation characteristic, optical frequency converting method and oximeter - Google Patents

Abstract

The invention discloses an optical frequency conversion device and method with temperature compensation characteristics and an oximeter, including a photodiode, an oscillator, a transimpedance amplifier, a transconductance amplifier and a current subtractor; A photodiode and a second photodiode that does not receive an optical signal; the transimpedance amplifiers are respectively a first transimpedance amplifier and a second transimpedance amplifier; the transconductance amplifiers are respectively a first transimpedance amplifier and a second transimpedance amplifier; the first The output terminal of the photodiode is connected to the first transconductance amplifier by the first transimpedance amplifier, and the output terminal of the second photodiode is connected to the second transconductance amplifier by the second transimpedance amplifier; the first transconductance amplifier and the second transconductance amplifier The output terminals are respectively connected to the input terminals of the current subtractor; the output terminals of the current subtractor are connected to the input terminals of the oscillator. The invention can offset the influence of temperature on the dark current of the photodiode and ensure the precision of the photoelectric conversion device.

Description

Optical frequency conversion device, method and oximeter with temperature compensation characteristics

technical field

The invention relates to the field of photoelectric conversion technology, in particular to an optical frequency conversion device, method and oximeter with temperature compensation characteristics.

Background technique

Photoelectric technology is a high-tech combination of traditional optical technology and modern electronic technology. The photoelectric conversion technology with photoelectric conversion circuit as the core has been widely used in many fields such as military, industry, agriculture, environmental science, medical treatment and aerospace. The so-called photoelectric conversion is based on semiconductor material photodiodes. By converting the amount of light flux irradiated on the photodiodes into corresponding current signals, it is further optimized into useful signals after subsequent circuits such as pre-amplification and main amplification. So that the subsequent circuit can process the signal. The optical frequency conversion device is a photoelectric conversion device that can generate a pulse signal of a corresponding frequency according to the detected light intensity, and is widely used in medical devices such as oximeters.

At present, most low-end oximeters on the market are composed of discrete components, such as photodiodes, sensitive amplifiers, ADC/DAC, reference voltage regulators, microprocessors, and LED display and drive. Large volume and high power consumption, and the consistency of accuracy is difficult to guarantee. High-end oximeters use light sensor chips instead of photodiodes, and some also use special devices such as light-to-frequency. The overall development trend is to integrate multiple analog functional modules and photoelectric sensors, and finally realize a small, light, and power-saving oximeter product. However, there is no photoelectric detection analog integrated chip dedicated to the oximeter that integrates modules such as photoelectric sensors, weak signal acquisition, and analog-to-digital conversion. Among them, the optical frequency conversion circuit is one of the key parts in the photoelectric detection analog integrated chip. The optical frequency conversion circuit uses a photodiode to convert the optical signal into a current signal, but the dark current in the output of the photodiode is greatly affected by temperature, which affects the accuracy of the optical frequency conversion circuit.

Therefore, in order to ensure the conversion accuracy, the optical frequency conversion circuit also needs a mechanism responsible for offsetting the influence of temperature on the dark current of the photodiode.

Contents of the invention

The object of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide an optical frequency conversion device with temperature compensation characteristics, which can offset the influence of temperature on the dark current of photodiodes and ensure the accuracy of the photoelectric conversion device.

The second object of the present invention is to provide an optical frequency conversion method implemented by the above-mentioned optical frequency conversion device with temperature compensation characteristics.

The third object of the present invention is to provide an oximeter.

The first object of the present invention is achieved through the following technical solutions: an optical frequency conversion device with temperature compensation characteristics, including a photodiode and an oscillator, and also includes a transimpedance amplifier, a transconductance amplifier and a current subtractor;

The number of the photodiodes is two, which are the first photodiode D1 that receives the light signal and generates a corresponding current signal according to the light intensity, and the second photodiode D2 that does not receive the light signal and generates a related current signal according to the temperature;

The number of the transimpedance amplifiers is two, respectively the first transimpedance amplifier and the second transimpedance amplifier;

The number of the transconductance amplifiers is two, respectively the first transconductance amplifier and the second transconductance amplifier;

The output end of the first photodiode D1 is connected to the first transconductance amplifier through the first transimpedance amplifier, and the output end of the second photodiode D2 is connected to the second transconductance amplifier through the second transimpedance amplifier; The output ends of the amplifier and the second transconductance amplifier are respectively connected to the two input ends of the current subtractor; the output end of the current subtractor is connected to the input end of the oscillator.

Preferably, the first transimpedance amplifier includes a resistor R1 and an operational amplifier A1; the anode of the first photodiode D1 is grounded, and the cathode is connected to the inverting input of the operational amplifier A1; the inverting input of the operational amplifier A1 Terminal is connected with the output terminal of operational amplifier A1 through resistance R1, and the noninverting input terminal of operational amplifier A1 is grounded; The output terminal of operational amplifier A1 is connected the input terminal of the first transimpedance amplifier as the output terminal of the first transimpedance amplifier;

The second transimpedance amplifier includes a resistor R2 and an operational amplifier A2; the anode of the second photodiode D2 is grounded, and the cathode is connected to the inverting input of the operational amplifier A2; the inverting input of the operational amplifier A2 passes through a resistor R2 is connected to the output terminal of the operational amplifier A2, and the non-inverting input terminal of the operational amplifier A2 is grounded; the output terminal of the operational amplifier A2 is connected to the input terminal of the second transimpedance amplifier as the output terminal of the second transimpedance amplifier.

Preferably, the first transimpedance amplifier includes an operational amplifier A3, a resistor R3 and a PMOS transistor P1, the output of the first transimpedance amplifier is connected to the inverting input of the operational amplifier A3, and the output of the operational amplifier A3 is connected to the PMOS The gate of the transistor P1, the non-inverting input terminal of the operational amplifier A3 are connected to the drain of the PMOS transistor P1, the drain of the PMOS transistor P1 is grounded through the resistor R3, and the source of the PMOS transistor P1 is connected to the power supply; the output terminal of the operational amplifier A3 is used as the first The output terminal of the transconductance amplifier is connected to one of the input terminals of the current subtractor;

The second transimpedance amplifier includes an operational amplifier A4, a resistor R4 and a PMOS transistor P2, the output of the second transimpedance amplifier is connected to the inverting input of the operational amplifier A4, and the output of the operational amplifier A4 is connected to the PMOS transistor P2 The gate, the non-inverting input terminal of the operational amplifier A4 is connected to the drain of the PMOS transistor P2, the drain of the PMOS transistor P2 is grounded through the resistor R4, and the source of the PMOS transistor P2 is connected to the power supply; the output terminal of the operational amplifier A4 is used as the second transconductance amplifier The output terminal of is connected to the other input terminal of the current subtractor.

Preferably, the current subtractor includes a PMOS transistor P3, a PMOS transistor P4, an NMOS transistor N1, an NMOS transistor N2, and an NMOS transistor N3, the output end of the first transconductance amplifier is connected to the gate of the PMOS transistor P3, and the second transconductance amplifier The output terminal of the conductance amplifier is connected to the gate of the PMOS transistor P4;

The source stage of the PMOS transistor P3 and the source stage of the PMOS transistor P4 are both connected to the power supply;

The drain of the PMOS transistor P3 is respectively connected to the drain of the NMOS transistor N2, the drain of the NMOS transistor N3, and the gate of the NMOS transistor N3; the drain of the PMOS transistor P4 is respectively connected to the drain of the NMOS transistor N1 and the gate of the NMOS transistor N1 The gate of the NMOS transistor N1 is connected to the gate of the NMOS transistor N2, the source of the NMOS transistor N1, the source of the NMOS transistor N2 and the source of the NMOS transistor N3 are all grounded, and the gate of the NMOS transistor N3 is used as a current subtractor The output terminal of the oscillator is connected to the input terminal of the oscillator.

Preferably, the oscillator includes PMOS transistor P5, PMOS transistor P6, PMOS transistor P7, NMOS transistor N4, NMOS transistor N5, NMOS transistor N6, capacitor C1, capacitor C2, inverter I1, inverter I2, inverter Device I3, inverter I4 and inverter I5;

The gate of NMOS transistor N4 is connected to the output terminal of the current subtractor, the sources of PMOS transistor P5 and PMOS transistor P6 are respectively connected to the power supply, the drain and gate of PMOS transistor P5 are respectively connected to the gate of PMOS transistor P6, and the PMOS transistor P5 The drain of the NMOS transistor N4 is connected to the drain of the NMOS transistor N4, and the source of the NMOS transistor N4 is grounded; the drain of the PMOS transistor P6 is respectively connected to the drain of the NMOS transistor N5, the gate of the NMOS transistor N5, and the gate of the NMOS transistor N6. The source of N5 is grounded;

The gate of the PMOS transistor P7 is connected to the gate of the PMOS transistor P6, the drain of the PMOS transistor P7 is connected to the drain of the NMOS transistor N6, the input terminal of the inverter I1 is connected to the drain of the PMOS transistor P7, and the output of the inverter I1 The terminal is connected to the input terminal of inverter I2 and inverter I3, the output terminal of inverter I2 is connected to the drain of PMOS transistor P7 through capacitor C1, and the output terminal of inverter I3 is respectively connected to inverter I4 and inverter The input terminal of I5 and the output terminal of inverter I4 are connected to the sources of PMOS transistor P7 and NMOS transistor N6, and the drain of PMOS transistor P7 is grounded through capacitor C2; the output terminal of inverter I5 is used as the output terminal of the oscillator to output the corresponding Frequency pulse signal.

The second object of the present invention is achieved through the following technical solution: an optical frequency conversion method based on the above-mentioned optical frequency conversion device with temperature compensation characteristics, the steps are as follows:

S1. The first photodiode D1 receives the light signal and converts it into a corresponding current signal according to the light intensity, and then transmits it to the first transimpedance amplifier; the first photodiode D2 does not receive the light signal, and generates a relevant current signal according to the temperature, and then sent to the second transimpedance amplifier;

S2. After the first transimpedance amplifier receives the current signal, it converts the current signal into a voltage signal, and then transmits it to the first transimpedance amplifier; after the second transimpedance amplifier receives the current signal, it converts the current signal into a voltage signal, and then sent to the second transconductance amplifier;

S3. After the first transconductance amplifier receives the voltage signal, it converts the voltage signal into a current signal in proportion, and transmits it to one of the input terminals of the current subtractor. After receiving the voltage signal, the second transconductance amplifier converts the voltage signal in proportion to The signal is converted into a current signal and sent to the other input of the current subtractor;

S4. The current subtractor performs subtraction processing on the current signals received by the two input terminals, and obtains a temperature-compensated current signal after the subtraction processing, and then transmits it to the oscillator;

S5. The oscillator generates a pulse signal of a corresponding frequency according to the temperature compensation current signal output by the current subtractor.

Preferably, the current signal output by the first transconductance amplifier in the step S3 is input to the current subtractor through the gate of the current subtractor PMOS transistor P3; the current signal output by the second transconductance amplifier is passed through the current subtractor PMOS The gate of the tube P4 is input to the current subtractor.

Preferably, in the step S4, the current subtractor outputs a temperature-compensated current signal to the input terminal of the oscillator through the gate of the NMOS transistor N3.

Preferably, in the step S5, the oscillator inputs a temperature compensation current signal through the gate of the NMOS transistor N4.

The third object of the present invention is achieved by the following technical solution: an oximeter, comprising the above-mentioned optical frequency conversion device with temperature compensation characteristics.

Compared with the prior art, the present invention has the following advantages and effects:

The device of the present invention includes two photodiodes, wherein the first photodiode is used to receive light signals and generate corresponding current signals according to light intensity, the second photodiode does not receive light signals and only generates relevant current signals according to temperature, and the two photodiodes The current signals generated by the diodes are respectively transmitted to two transimpedance amplifiers for impedance transformation, and the current signals output by the two photodiodes are converted into voltage signals through the two transimpedance amplifiers, and then transmitted to the two transimpedance amplifiers respectively. The two transconductance amplifiers respectively convert the input voltage signal into a current signal according to the ratio, and then transmit them to the two input terminals of the current subtractor, and the current subtractor performs subtraction processing on the two input signals to subtract the photodiode Because of the current signal generated by the temperature, a temperature-compensated current signal is obtained, and the temperature-compensated current signal is input into the oscillator. The oscillator generates a pulse signal of a corresponding frequency according to the magnitude of the input current to realize optical frequency conversion with temperature compensation. , offset the influence of temperature on the dark current of the photodiode, and ensure the accuracy of the photoelectric conversion device.

Description of drawings

Fig. 1 is a block diagram of the structure and composition of the optical frequency conversion device of the present invention.

Fig. 2 is a schematic circuit diagram of the optical frequency conversion device of the present invention.

Fig. 3 is a diagram of the pulse signal output by the optical frequency conversion device of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

As shown in Figure 1, this embodiment discloses an optical frequency conversion device with temperature compensation characteristics, including a photodiode, a transimpedance amplifier, a transconductance amplifier, a current subtractor, and an oscillator;

The number of photodiodes is two, which are the first photodiode D1 that receives the light signal and generates a corresponding current signal according to the light intensity, and the second photodiode D2 that does not receive the light signal and generates a related current signal according to the temperature; that is, the first photodiode D1 is used to receive the light signal, the second photodiode does not receive the light signal, but only generates the current signal with light corresponding to the temperature.

The number of transimpedance amplifiers is two, respectively the first transimpedance amplifier 11 and the second transimpedance amplifier 12;

The number of transconductance amplifiers is two, respectively the first transconductance amplifier 21 and the second transconductance amplifier 22;

The output terminal of the first photodiode D1 connects the first transconductance amplifier 21 through the first transimpedance amplifier 11, and the output terminal of the second photodiode D2 connects the second transconductance amplifier 22 through the second transimpedance amplifier 12; The output terminals of the amplifier 21 and the second transconductance amplifier 22 are respectively connected to the two input terminals of the current subtractor 3 ; the output terminal of the current subtractor 3 is connected to the input terminal of the oscillator 4 .

As shown in Figure 2, the first transimpedance amplifier 11 includes a resistor R1 and an operational amplifier A1; the anode of the first photodiode D1 is grounded, and the cathode is connected to the inverting input of the operational amplifier A1; the inverting input of the operational amplifier A1 Terminal is connected with the output terminal of operational amplifier A1 through resistance R1, and the noninverting input terminal of operational amplifier A1 is grounded; The output terminal of operational amplifier A1 is connected the input terminal of first transimpedance amplifier 21 as the output terminal of the first transimpedance amplifier 11; Through The first transimpedance amplifier 11 converts the current output by the first photodiode D1 into a voltage signal. The voltage signal V11 output by the first transimpedance amplifier ₁₁ is:

V ₁₁ =I ₁₁ *R ₁ ;

Wherein I ₁₁ is the current output by the first photodiode D1.

The second transimpedance amplifier 12 comprises resistor R2 and operational amplifier A2; The anode of the second photodiode D2 is grounded, and the negative electrode is connected with the inverting input terminal of described operational amplifier A2; The inverting input terminal of operational amplifier A2 passes resistance R2 and operation The output end of amplifier A2 is connected, and the non-inverting input end of operational amplifier A2 is grounded; The output end of operational amplifier A2 is connected the input end of second transimpedance amplifier 22 as the output end of second transimpedance amplifier 12; Through second transimpedance amplifier 12 The current output by the second photodiode D1 is converted into a voltage signal. The voltage signal V12 output by the second transimpedance amplifier ₁₂ is:

V ₁₂ =I ₁₂ *R ₂ ;

Wherein I ₁₂ is the current output by the second photodiode D2.

The first transimpedance amplifier 21 includes an operational amplifier A3, a resistor R3 and a PMOS transistor P1, the output terminal of the first transimpedance amplifier 11 is connected to the inverting input terminal of the operational amplifier A3, and the output terminal of the operational amplifier A3 is connected to the gate of the PMOS transistor P1 , the non-inverting input terminal of the operational amplifier A3 is connected to the drain of the PMOS transistor P1, the drain of the PMOS transistor P1 is grounded through the resistor R3, and the source of the PMOS transistor P1 is connected to the power supply; the output terminal of the operational amplifier A3 is used as the first transconductance amplifier 21 The output terminal is connected to one of the input terminals of the current subtractor; the voltage signal output by the first transimpedance amplifier is converted into a current signal in proportion through the first transconductance amplifier 21 . Wherein the conversion ratio relationship of the first transconductance amplifier 21 is as follows:

I ₂₁ =V ₁₁ /R ₃ ;

Where V ₁₁ is the voltage signal output by the first transimpedance amplifier.

The second transimpedance amplifier 22 includes an operational amplifier A4, a resistor R4 and a PMOS transistor P2, the output of the second transimpedance amplifier 21 is connected to the inverting input of the operational amplifier A4, and the output of the operational amplifier A4 is connected to the gate of the PMOS transistor P2 , the non-inverting input terminal of the operational amplifier A4 is connected to the drain of the PMOS transistor P2, the drain of the PMOS transistor P2 is grounded through the resistor R4, and the source of the PMOS transistor P2 is connected to the power supply; the output terminal of the operational amplifier A4 is used as the second transconductance amplifier 22 The output terminal is connected to the other input terminal of the current subtractor 3 . The voltage signal output by the second transimpedance amplifier 12 is proportionally converted into a current signal by the second transconductance amplifier 22 .

Wherein the conversion ratio relationship of the first transconductance amplifier 21 is as follows:

I ₂₂ =V ₁₂ /R ₄ ;

Where V ₁₂ is the voltage signal output by the second transimpedance amplifier.

The current subtractor 3 includes a PMOS transistor P3, a PMOS transistor P4, an NMOS transistor N1, an NMOS transistor N2 and an NMOS transistor N3; the output end of the first transconductance amplifier 21 is connected to the gate of the PMOS transistor P3, and the PMOS transistor P3 passes through the mirror image of the PMOS transistor P1 The current signal obtained by the first transconductance amplifier 21 output; the output terminal of the second transconductance amplifier 22 is connected to the gate of the PMOS transistor P4, and the PMOS transistor P4 obtains the output signal of the second transconductance amplifier 22 by mirroring the current of the PMOS transistor P2 current signal;

The source stage of the PMOS transistor P3 and the source stage of the PMOS transistor P4 are both connected to the power supply;

The drain of the PMOS transistor P3 is respectively connected to the drain of the NMOS transistor N2, the drain of the NMOS transistor N3, and the gate of the NMOS transistor N3; the drain of the PMOS transistor P4 is respectively connected to the drain of the NMOS transistor N1 and the gate of the NMOS transistor N1 The gate of the NMOS transistor N1 is connected to the gate of the NMOS transistor N2, the source of the NMOS transistor N1, the source of the NMOS transistor N2 and the source of the NMOS transistor N3 are all grounded, and the gate of the NMOS transistor N3 is used as a current subtractor The output terminal of 3 is connected to the input terminal of oscillator 4 . After the two-way current signals input into the current subtractor 3 are subtracted by the current subtractor, they pass through the gate output of the NMOS transistor N3 of the current subtractor 3, and the current subtractor 3 obtains the subtraction of the two-way signals. The current signal, that is, the influence of temperature on the dark current of the photodiode is offset by subtraction processing, and the current signal after temperature compensation is obtained.

In the current subtractor 3 of this embodiment, the drain of the PMOS transistor P3 is connected with the drain of the NMOS transistor N2 and the drain of the NMOS transistor N3, so part of the current flowing through the PMOS transistor P3 flows into the NMOS transistor N2, and the other part Flow into NMOS tube N3. The NMOS transistor N1 and the PMOS transistor P4 are in the same branch, and the currents flowing through them are equal; and the NMOS transistor N2 mirrors the current of the NMOS transistor N1, that is, the current flowing through the NMOS transistor N2 is equal to the current flowing through the PMOS transistor P4. Therefore, a part of the current flowing through the PMOS transistor P3 having the same magnitude as that of the PMOS transistor P4 flows away through the NMOS transistor N2, and the rest flows into the NMOS transistor N3, thereby achieving the purpose of current subtraction.

The oscillator 4 includes PMOS transistor P5, PMOS transistor P6, PMOS transistor P7, NMOS transistor N4, NMOS transistor N5, NMOS transistor N6, capacitor C1, capacitor C2, inverter I1, inverter I2, inverter I3, inverter phase device I4 and inverter I5;

The gate of the NMOS transistor N4 is connected to the output terminal of the current subtractor 3, the sources of the PMOS transistor P5 and the PMOS transistor P6 are respectively connected to the power supply, the drain and the gate of the PMOS transistor P5 are respectively connected to the gate of the PMOS transistor P6, and the PMOS transistor P6 The drain of P5 is connected to the drain of NMOS transistor N4, and the source of NMOS transistor N4 is grounded; the drain of PMOS transistor P6 is respectively connected to the drain of NMOS transistor N5, the gate of NMOS transistor N5, and the gate of NMOS transistor N6. The source of the tube N5 is grounded;

The gate of the PMOS transistor P7 is connected to the gate of the PMOS transistor P6, the drain of the PMOS transistor P7 is connected to the drain of the NMOS transistor N6, the input terminal of the inverter I1 is connected to the drain of the PMOS transistor P7, and the output of the inverter I1 The terminal is connected to the input terminal of inverter I2 and inverter I3, the output terminal of inverter I2 is connected to the drain of PMOS transistor P7 through capacitor C1, and the output terminal of inverter I3 is respectively connected to inverter I4 and inverter The input terminal of I5 and the output terminal of inverter I4 are connected to the sources of PMOS transistor P7 and NMOS transistor N6, and the drain of PMOS transistor P7 is grounded through capacitor C2; the output terminal of inverter I5 is output as the output terminal of oscillator 4 Pulse signal of corresponding frequency. As shown in FIG. 3 , the pulse signal output by the oscillator 4 of this embodiment is shown.

In the oscillator 4 of this embodiment, it is assumed that the oscillator 4 outputs a high level at this time, that is, the inverter I4 outputs a high level at this time, and the input terminal of the inverter I1 is a low level. At this time, the PMOS transistor P7 is turned on, the NMOS transistor N6 is turned off, the capacitors C1 and C2 are charged by the input current of the PMOS transistor P7, and the potential of the input terminal of the inverter I1 continues to rise. When the potential at the input terminal of the inverter I1 rises beyond the forward threshold voltage of the inverter I1, the outputs of the inverter I1, the inverter I2, the inverter I3, the inverter I4 and the inverter I5 are reversed, Oscillator 4 outputs low level. That is, at this time, the output of the inverter I4 is at a low level, and the input terminal of the inverter I1 is at a high level. At this time, the PMOS transistor P7 is turned off, the NMOS transistor N6 is turned on, the capacitors C1 and C2 are discharged through the current flowing out of the NMOS transistor N6, and the potential of the input terminal of the inverter I1 decreases continuously. When the potential of the input terminal of the inverter I1 drops beyond the reverse threshold voltage of the inverter I1, the outputs of the inverter I1, the inverter I2, the inverter I3, the inverter I4, and the inverter I5 flip and oscillate The device 4 outputs a high level again, and re-enters the above-mentioned cycle, thereby generating oscillation and outputting a pulse signal. The oscillating frequency f _clk of the pulse signal that oscillator 4 obtains in the present embodiment is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; D.</span>}}}<span\; class="notranslate">\; ;</span>$

Among them, V _{t, r} is the forward threshold voltage of inverter I1, V _{t, f} is the reverse threshold voltage of inverter I1, I ₄ is the input voltage of inverter I4, and V _DD is the power supply voltage.

This embodiment also discloses an optical frequency conversion method implemented by the above-mentioned optical frequency conversion device with temperature compensation characteristics, the steps are as follows:

S1. The first photodiode D1 receives the light signal and converts it into a corresponding current signal according to the light intensity, and then transmits it to the first transimpedance amplifier; the first photodiode D2 does not receive the light signal, and generates a relevant current signal according to the temperature, and then sent to the second transimpedance amplifier;

S2. After the first transimpedance amplifier receives the current signal, it converts the current signal into a voltage signal, and then transmits it to the first transimpedance amplifier; after the second transimpedance amplifier receives the current signal, it converts the current signal into a voltage signal, and then sent to the second transconductance amplifier;

In this embodiment, the voltage signal V output by the first transimpedance amplifier ₁₁ is:

V ₁₁ =I ₁₁ *R ₁ ;

Wherein I ₁₁ is the current output by the first photodiode D1.

In the present embodiment, the voltage signal V12 output by the second transimpedance amplifier ₁₂ is:

V ₁₂ =I ₁₂ *R ₂ ;

Wherein I ₁₂ is the current output by the second photodiode D2.

S3. After the first transconductance amplifier receives the voltage signal, it converts the voltage signal into a current signal in proportion, and transmits it to one of the input terminals of the current subtractor. After receiving the voltage signal, the second transconductance amplifier converts the voltage signal in proportion to The signal is converted into a current signal, and sent to the other input terminal of the current subtractor; in this step, the current signal output by the first transconductance amplifier is input into the current subtractor through the gate of the current subtractor PMOS transistor P3; the second transconductance The current signal output by the conductance amplifier is input to the current subtractor through the gate of the current subtractor PMOS transistor P4.

In this embodiment, the conversion ratio of converting the voltage signal of the first transconductance amplifier into a current signal is:

I ₂₁ =V ₁₁ /R ₃ ;

Where V ₁₁ is the voltage signal output by the first transimpedance amplifier.

In this embodiment, the conversion ratio of converting the voltage signal of the second transconductance amplifier into a current signal is:

I ₂₂ =V ₁₂ /R ₄ ;

Where V ₁₂ is the voltage signal output by the second transimpedance amplifier.

S4. The current subtractor performs subtraction processing on the current signals received by the two input terminals, and obtains a temperature-compensated current signal after the subtraction processing, and then transmits it to the oscillator; in this step, the current subtractor passes through the gate of the NMOS transistor N3 The pole outputs a temperature-compensated current signal to the input of the oscillator.

S5. The oscillator generates a pulse signal of a corresponding frequency according to the temperature compensation current signal output by the current subtractor. In this step, the oscillator inputs a temperature compensation current signal through the gate of the NMOS transistor N4. The oscillation frequency _fclk of the pulse signal obtained by the oscillator in the present embodiment is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; D.</span>}}}<span\; class="notranslate">\; ;</span>$

Where V _{t, r} is the forward threshold voltage of the inverter I1 in the oscillator, V _{t, f} is the reverse threshold voltage of the inverter I1 in the oscillator, I ₄ is the input voltage of the inverter I4 in the oscillator, V _DD is the supply voltage.

This embodiment also discloses an oximeter, comprising the above-mentioned optical frequency conversion device with temperature compensation characteristics.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. there is an apparatus for frequency conversion for temperature compensation characteristic, comprise photodiode and oscillator, it is characterized in that, also comprise trans-impedance amplifier, trsanscondutance amplifier and current subtractor;

The number of described photodiode is two, be respectively receiving optical signals according to light intensity produce corresponding current signal the first photodiode D1 and not receiving optical signals to produce the second photodiode D2 of correlated current signal according to temperature;

The number of described trans-impedance amplifier is two, is respectively the first trans-impedance amplifier and the second trans-impedance amplifier;

The number of described trsanscondutance amplifier is two, is respectively the first trsanscondutance amplifier and the second trsanscondutance amplifier;

The outfan of described first photodiode D1 connects the first trsanscondutance amplifier by the first trans-impedance amplifier, and the outfan of described second photodiode D2 connects the second trsanscondutance amplifier by the second trans-impedance amplifier; First trsanscondutance amplifier and the outfan of the second trsanscondutance amplifier are connected two inputs of current subtractor respectively; The outfan of current subtractor connects the input of oscillator.

2. the apparatus for frequency conversion with temperature compensation characteristic according to claim 1, is characterized in that, described first trans-impedance amplifier comprises resistance R1 and operational amplifier A 1; The plus earth of the first photodiode D1, negative electrode is connected with the inverting input of described operational amplifier A 1; The inverting input of described operational amplifier A 1 is connected with the outfan of operational amplifier A 1 by resistance R1, the in-phase input end ground connection of operational amplifier A 1; The outfan of operational amplifier A 1 connects the input of the first trsanscondutance amplifier as the outfan of the first trans-impedance amplifier;

Described second trans-impedance amplifier comprises resistance R2 and operational amplifier A 2; The plus earth of the second photodiode D2, negative electrode is connected with the inverting input of described operational amplifier A 2; The inverting input of described operational amplifier A 2 is connected with the outfan of operational amplifier A 2 by resistance R2, the in-phase input end ground connection of operational amplifier A 2; The outfan of operational amplifier A 2 connects the input of the second trsanscondutance amplifier as the outfan of the second trans-impedance amplifier.

3. the apparatus for frequency conversion with temperature compensation characteristic according to claim 1, it is characterized in that, described first trsanscondutance amplifier comprises operational amplifier A 3, resistance R3 and PMOS P1, the inverting input of the outfan concatenation operation amplifier A3 of described first trans-impedance amplifier, the outfan of operational amplifier A 3 connects the grid of PMOS P1, the in-phase input end of operational amplifier A 3 connects the drain electrode of PMOS P1, the drain electrode of PMOS P1 is by resistance R3 ground connection, and the source electrode of PMOS P1 connects power supply; The outfan of operational amplifier A 3 connects one of them input of current subtractor as the outfan of the first trsanscondutance amplifier;

Described second trsanscondutance amplifier comprises operational amplifier A 4, resistance R4 and PMOS P2, the inverting input of the outfan concatenation operation amplifier A4 of described second trans-impedance amplifier, the outfan of operational amplifier A 4 connects the grid of PMOS P2, the in-phase input end of operational amplifier A 4 connects the drain electrode of PMOS P2, the drain electrode of PMOS P2 is by resistance R4 ground connection, and the source electrode of PMOS P2 connects power supply; The outfan of operational amplifier A 4 connects another input of current subtractor as the outfan of the second trsanscondutance amplifier.

4. the apparatus for frequency conversion with temperature compensation characteristic according to claim 1, it is characterized in that, described current subtractor comprises PMOS P3, PMOS P4, NMOS tube N1, NMOS tube N2 and NMOS tube N3, the outfan of described first trsanscondutance amplifier connects the grid of PMOS P3, and the outfan of the second trsanscondutance amplifier connects the grid of PMOS P4;

The source class of PMOS P3 and the source class of PMOS P4 all connect power supply;

The drain electrode of PMOS P3 connects the grid of the drain electrode of NMOS tube N2, the drain electrode of NMOS tube N3 and NMOS tube N3 respectively; The drain electrode of PMOS P4 connects the drain electrode of NMOS tube N1 and the grid of NMOS tube N1 respectively; The grid of NMOS tube N1 is connected with the grid of NMOS tube N2, the source grounding of the source electrode of NMOS tube N1, the source electrode of NMOS tube N2 and NMOS tube N3, and wherein the grid of NMOS tube N3 connects the input of oscillator as the outfan of current subtractor.

5. the apparatus for frequency conversion with temperature compensation characteristic according to claim 1, it is characterized in that, described oscillator comprises PMOS P5, PMOS P6, PMOS P7, NMOS tube N4, NMOS tube N5, NMOS tube N6, electric capacity C1, electric capacity C2, phase inverter I1, phase inverter I2, phase inverter I3, phase inverter I4 and phase inverter I5;

The grid of NMOS tube N4 connects the outfan of current subtractor, the source electrode of PMOS P5 and PMOS P6 connects power supply respectively, the drain and gate of PMOS P5 is connected with the grid of PMOS P6 respectively, and the drain electrode of PMOS P5 connects the drain electrode of NMOS tube N4, the source ground of NMOS tube N4; The drain electrode of PMOS P6 connects the grid of the drain electrode of NMOS tube N5, the grid of NMOS tube N5 and NMOS tube N6 respectively, the source ground of NMOS tube N5;

The grid of PMOS P7 connects the grid of PMOS P6, the drain electrode of PMOS P7 is connected with the drain electrode of NMOS tube N6, the input of phase inverter I1 connects the drain electrode of PMOS P7, the outfan of phase inverter I1 connects the input of phase inverter I2 and phase inverter I3, the outfan of phase inverter I2 connects the drain electrode of PMOS P7 by electric capacity C1, the outfan of phase inverter I3 connects the input of phase inverter I4 and phase inverter I5 respectively, the outfan of phase inverter I4 connects the source electrode of PMOS P7 and NMOS tube N6, and the drain electrode of PMOS P7 is by electric capacity C2 ground connection; The outfan of phase inverter I5 exports the pulse signal of corresponding frequencies as the outfan of oscillator.

6., based on the light frequency conversion method that the apparatus for frequency conversion with temperature compensation characteristic according to claim 1 realizes, it is characterized in that, step is as follows:

S1, the first photodiode D1 receiving optical signals convert thereof into corresponding current signal according to light intensity, then send the first trans-impedance amplifier to; The non-receiving optical signals of first photodiode D2, produces correlated current signal according to temperature, then sends the second trans-impedance amplifier to;

After S2, the first trans-impedance amplifier receive current signal, convert current signal to voltage signal, then send the first trsanscondutance amplifier to; After second trans-impedance amplifier receives current signal, convert current signal to voltage signal, then send the second trsanscondutance amplifier to;

After S3, the first trsanscondutance amplifier receive voltage signal, proportionally convert voltage signal to current signal, and send one of them input of current subtractor to, after second trsanscondutance amplifier receives voltage signal, proportionally convert voltage signal to current signal, and send another input of current subtractor to;

The current signal that two inputs receive by S4, current subtractor carries out subtracting each other process, obtains the current signal of temperature-compensating, then transmit to oscillator after subtracting each other process;

S5, oscillator produce the pulse signal of corresponding frequencies according to the temperature-compensated current signal that current subtractor exports.

7. light frequency conversion method according to claim 6, is characterized in that, the current signal that in described step S3, the first trsanscondutance amplifier exports is input in current subtractor by the grid of current subtractor PMOS P3; The current signal that described second trsanscondutance amplifier exports is input in current subtractor by the grid of current subtractor PMOS P4.

8. light frequency conversion method according to claim 6, is characterized in that, in described step S4, the current signal that current subtractor is compensated by the grid output temperature of NMOS tube N3 is to the input of oscillator.

9. light frequency conversion method according to claim 6, is characterized in that, in described step S5, described oscillator is by the grid input temp compensating current signal of NMOS tube N4.

10. a BOLD contrast, is characterized in that, comprises the apparatus for frequency conversion with temperature compensation characteristic according to any one of claim 1 to 5.