An IV conversion circuit and infrared receiver chip resistant to strong light interference

Abstract

This invention discloses an I-V conversion circuit resistant to strong light interference, relating to the field of integrated circuit technology. It includes an infrared photodiode VD, resistors R1 and R2, an amplifier AMP, and PMOS transistors M1, M2, and C. The invention also discloses an I-V conversion circuit resistant to strong light interference, including an infrared photodiode VD, resistors R1 and R2, amplifiers AMP1 and AMP2, NMOS transistors M1, M2, and M3, and capacitor C. Furthermore, the invention discloses an infrared receiving chip incorporating the aforementioned I-V conversion circuit resistant to strong light interference. Under strong light conditions, this invention prevents the output voltage OUT from continuously increasing, effectively receiving, identifying, and amplifying the input signal, thus improving signal quality and reducing distortion.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to an IV conversion circuit and an infrared receiving chip that are resistant to strong light interference. Background Technology

[0002] In nature, almost all quantities that can represent information are analog quantities. However, in signal processing, appropriate conversions are needed, generally converting analog signals into digital signals or quantities that are beneficial for subsequent processing. Infrared photodiodes, also called infrared receiving diodes, convert light signals into electrical signals. In existing photoelectric IV conversion circuits, the negative input terminal of amplifier AMP1 is the reference voltage VREF1, and the reverse bias voltage of infrared photodiode VD1 is the feedback voltage. Ambient light signals are converted into photocurrents by infrared photodiode VD1, and then converted into output voltage OUT1 after passing through a 300K fixed resistor R1. As the ambient light intensity gradually increases, the photocurrent gradually increases, and the output voltage OUT1 also gradually increases, approaching the power supply voltage. When infrared light is received from the transmitter, a small signal is generated, namely a current signal with a very small amplitude, which is added to the photocurrent. As the ambient light intensity gradually increases, the output voltage OUT1 gradually rises to the power supply voltage due to the increasing photocurrent, and the distortion of the small signal becomes increasingly severe. Existing technology addresses small-signal distortion using a variable resistor structure. This structure exhibits a small resistance value under high current input to prevent amplifier saturation distortion, and a large resistance value under low current input. However, under different process conditions, the current flowing through the resistor can become very small, resulting in a significant reduction in the reverse voltage applied to the diode, thus presenting a drawback.

[0003] Therefore, those skilled in the art are dedicated to developing an IV conversion circuit and an infrared receiving chip that are resistant to strong light interference. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to prevent the output voltage OUT1 from continuously increasing under strong light conditions, causing small signal distortion and signal quality reduction, so as to enable accurate processing of small signals.

[0005] The inventors discovered through research that by shunting the photocurrent to prevent the current flowing through the resistor from continuously increasing, and by adjusting the amplifier's output voltage through feedback voltage changes, the range of output voltage variation can be further adjusted, thus preventing small signals from being distorted and allowing small signals to be processed better.

[0006] In one embodiment of the present invention, an IV conversion circuit resistant to strong light interference is provided, including an infrared photodiode VD2, a resistor R2, a resistor R3, an amplifier AMP2, a PMOS transistor M2, an NMOS transistor M3, and a capacitor C1;

[0007] The forward terminal of infrared photodiode VD2 is grounded. The reverse terminal of infrared photodiode VD2 is connected to the source of NMOS transistor M3, the non-inverting terminal of amplifier AMP2, and one end of resistor R2. The other end of resistor R2 is connected to one end of resistor R3 and the drain of PMOS transistor M2. The other end of resistor R3 is connected to the gate of NMOS transistor M3 and one end of capacitor C1. The other end of capacitor C1 is grounded. The drain of NMOS transistor M3 and the source of PMOS transistor M2 are connected to the power supply voltage VDD. The reverse terminal of amplifier AMP2 is connected to the reference voltage VREF2. The output of amplifier AMP2 is connected to the gate of PMOS transistor M2.

[0008] As the ambient light intensity gradually increases, the photocurrent gradually increases. The photocurrent flowing through resistor R2 gradually increases, the drain voltage of PMOS transistor M2 (i.e., the output voltage OUT2) gradually increases, the gate voltage of NMOS transistor M3 gradually increases, NMOS transistor M3 turns on, the photocurrent is shunted, the output voltage of amplifier AMP2 increases, the absolute value of the gate-source voltage of PMOS transistor M2 decreases, the photocurrent flowing through PMOS transistor M2 is adjusted to decrease, the drain voltage of PMOS transistor M2 (i.e., the output voltage OUT2) decreases, fluctuating within a small range, so that small signals do not become distorted.

[0009] Furthermore, in the IV conversion circuit for resisting strong light interference in the above embodiment, the value of resistor R2 is greater than or equal to 200KΩ and less than or equal to 300KΩ, and the value of resistor R3 is at least 100 times greater than the value of resistor R2.

[0010] Preferably, in the IV conversion circuit for resisting strong light interference in the above embodiment, the resistor R2 = 300KΩ.

[0011] Furthermore, in the IV conversion circuit for resisting strong light interference in the above embodiment, the capacitor C1 is greater than 10pF.

[0012] Furthermore, in the IV conversion circuit for resisting strong light interference in the above embodiment, the capacitor C1 has a value of 20pF.

[0013] Furthermore, in the strong light interference-resistant IV conversion circuit of the above embodiment, the open-loop gain of amplifier AMP2 is greater than 70dB.

[0014] Furthermore, in the strong light interference-resistant IV conversion circuit of the above embodiment, the open-loop gain of amplifier AMP2 is 80dB.

[0015] Furthermore, in the strong light interference-resistant IV conversion circuit of the above embodiment, the applicable light intensity is within 10,000 LUX.

[0016] The inventors analyzed that when the light intensity exceeds 10,000 LUX, the NMOS transistor M3 will generate some noise, resulting in a large photocurrent, excessive amplification, and small-signal distortion. Considering the diversity of application scenarios, the inventors continued to improve the IV conversion circuit to combat strong light interference.

[0017] In another embodiment of the present invention, an IV conversion circuit resistant to strong light interference is provided, including an infrared photodiode VD3, a resistor R4, a resistor R5, an amplifier AMP3, an amplifier AMP4, an NMOS transistor M6, a PMOS transistor M4, a PMOS transistor M5, and a capacitor C2.

[0018] The forward terminal of infrared photodiode VD3 is grounded, and the reverse terminal is connected to the non-inverting terminal of amplifier AMP4, the source of NMOS transistor M6, and the drain of PMOS transistor M5. The non-inverting terminal of amplifier AMP3 is connected to the drain of PMOS transistor M4, the source of PMOS transistor M5, and one end of resistor R4. The other end of resistor R4 is connected to the drain of NMOS transistor M6 and one end of resistor R5. The other end of resistor R5 is connected to one end of capacitor C1 and the gate of PMOS transistor M5. The other end of capacitor C2 is grounded. The source of PMOS transistor M4 is connected to the power supply voltage VDD. The reverse terminals of amplifier AMP3 and amplifier AMP4 are connected to the reference voltages VREF3 and VREF4, respectively. The output of amplifier AMP3 is connected to the gate of PMOS transistor M4, and the output of amplifier AMP4 is connected to the gate of NMOS transistor M6.

[0019] As the light intensity gradually increases, the photocurrent of the infrared photodiode VD3 gradually increases, the drain voltage (output voltage OUT) of the PMOS transistor M4 gradually increases, the source voltage of the PMOS transistor M5 gradually increases, and the absolute value of the gate-source voltage gradually increases. The PMOS transistor M5 turns on, the photocurrent is shunted, the gate voltage of the PMOS transistor M4 increases, and the absolute value of the gate-source voltage decreases, thus regulating the overall photocurrent to decrease. The drain voltage (output voltage OUT) of the PMOS transistor M4 decreases, fluctuating within a small range to prevent distortion of small signals.

[0020] Furthermore, in the IV conversion circuit for resisting strong light interference in the above embodiment, the value of resistor R4 is greater than or equal to 200KΩ and less than or equal to 300KΩ, and the value of resistor R5 is at least 100 times greater than the value of resistor R4.

[0021] Preferably, in the IV conversion circuit for resisting strong light interference in the above embodiment, the resistor R4 = 300KΩ.

[0022] Furthermore, in the IV conversion circuit for resisting strong light interference in the above embodiment, the capacitor C2 is greater than 10pF.

[0023] Furthermore, in the IV conversion circuit for resisting strong light interference in the above embodiment, the capacitor C2 has a value of 20pF.

[0024] Furthermore, in the strong light interference-resistant IV conversion circuit of the above embodiment, the open-loop gain of amplifiers AMP3 and AMP4 is greater than 70dB.

[0025] Furthermore, in the strong light interference-resistant IV conversion circuit of the above embodiment, the open-loop gain of amplifier AMP3 and amplifier AMP4 is 80dB.

[0026] Based on any of the above embodiments, in another embodiment of the present invention, an infrared receiving chip is provided, the infrared receiving chip being provided with an IV conversion circuit for resisting strong light interference as described in any of the above embodiments.

[0027] This invention improves upon existing IV conversion circuits by feeding back the reverse voltage of the infrared photodiode to the output voltage, thereby controlling the range of output voltage OUT3. This prevents small signals from being distorted and avoids the continuous increase of output voltage OUT3 under strong light conditions. It can effectively receive, identify, and amplify input signals, improving signal quality and reducing distortion.

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the structure of a prior art photoelectric IV conversion circuit according to an exemplary embodiment;

[0030] Figure 2 This is a schematic diagram of the structure of an IV conversion circuit that resists strong light interference according to an exemplary embodiment;

[0031] Figure 3 The diagram illustrates the structure of an IV conversion circuit resistant to strong light interference according to an exemplary embodiment.

[0032] Figure 4 This is a schematic diagram illustrating the structure of an infrared receiver chip according to an exemplary embodiment. Detailed Implementation

[0033] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0034] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of components is schematically exaggerated in some places in the drawings.

[0035] The inventors analyzed existing photoelectric IV conversion circuits, such as... Figure 1 As shown, the negative input terminal of amplifier AMP1 is the reference voltage VREF1, and the reverse bias voltage of infrared photodiode VD1 is the feedback voltage. The ambient light signal is converted into a photocurrent by infrared photodiode VD1, and then converted into an output voltage OUT1 after passing through a 300K fixed resistor R1. As the ambient light intensity gradually increases, the photocurrent gradually increases, and the output voltage OUT1 also gradually increases, approaching the power supply voltage. When infrared light emitted from the transmitter is received, a small signal is generated, namely a current signal with a very small amplitude, which is added to the photocurrent. As the ambient light intensity gradually increases, the output voltage OUT1 gradually rises to the power supply voltage due to the increasing photocurrent, and the small signal distortion becomes increasingly severe. Existing technology treats small signal distortion through a variable resistor structure, which presents a small resistance value when the input current is large to avoid saturation distortion of the amplifier, and a large resistance value when the input current is small. However, under different process corners, the current flowing through the resistor can be very small, which greatly reduces the reverse voltage applied to the diode.

[0036] The inventors discovered through research that by shunting the photocurrent to prevent the current flowing through the resistor from continuously increasing, and by adjusting the output voltage of the amplifier through changes in the feedback voltage of the amplifier, the range of output voltage variation can be further adjusted, so that small signals will not be distorted and can be processed better.

[0037] The inventor designed an IV conversion circuit that resists strong light interference, such as Figure 2 As shown, the system includes: an infrared photodiode VD2, resistors R2 and R3, an amplifier AMP2, a PMOS transistor M2, an NMOS transistor M3, and a capacitor C1; wherein, resistor R2 has a value of 300KΩ, and resistor R3 has a value 100 times larger than that of resistor R2; capacitor C1 has a value of 20pF; the open-loop gain of amplifier AMP2 is 80dB.

[0038] The forward terminal of infrared photodiode VD2 is grounded. The reverse terminal of infrared photodiode VD2 is connected to the source of NMOS transistor M3, the non-inverting terminal of amplifier AMP2, and one end of resistor R2. The other end of resistor R2 is connected to one end of resistor R3 and the drain of PMOS transistor M2. The other end of resistor R3 is connected to the gate of NMOS transistor M3 and one end of capacitor C1. The other end of capacitor C1 is grounded. The drain of NMOS transistor M3 and the source of PMOS transistor M1 are connected to the power supply voltage VDD. The reverse terminal of amplifier AMP2 is connected to the reference voltage VREF2. The output of amplifier AMP2 is connected to the gate of PMOS transistor M2.

[0039] As the ambient light intensity gradually increases, the photocurrent gradually increases. The photocurrent flowing through resistor R2 gradually increases, the drain voltage of PMOS transistor M2 (i.e., the output voltage OUT2) gradually increases, the gate voltage of NMOS transistor M3 gradually increases, NMOS transistor M3 turns on, the photocurrent is shunted, the output voltage of amplifier AMP2 increases, the absolute value of the gate-source voltage of PMOS transistor M2 decreases, the photocurrent flowing through PMOS transistor M2 is adjusted to decrease, the drain voltage of PMOS transistor M2 (i.e., the output voltage OUT2) decreases, fluctuating within a small range, so that small signals do not become distorted.

[0040] The IV conversion circuit for resisting strong light interference in this embodiment is suitable for light intensities up to 10,000 LUX.

[0041] A comparative experiment was conducted using a remote control equipped with the above embodiments and a remote control of the prior art. In a typical household application scenario, as the light intensity was continuously increased, when the light intensity reached 5000 LUX, the signal reception of the remote control using the prior art deteriorated, and it could not control the device normally. However, the remote control equipped with the above embodiments showed significant resistance to strong light interference and could receive signals and control the device normally. As the light intensity was continuously increased, when the light intensity increased to 10,000 LUX, the reception of the remote control equipped with the above embodiments deteriorated, and it could not control the device normally.

[0042] The inventors analyzed that when the light intensity exceeds 10,000 LUX, the NMOS transistor M3 will generate some noise, resulting in a large photocurrent, excessive amplification, and small-signal distortion. Considering the diversity of application scenarios, the inventors continued to improve the IV conversion circuit to combat strong light interference.

[0043] The inventors have provided another embodiment, such as Figure 3As shown, the system includes an infrared photodiode VD3, resistors R4 and R5, amplifiers AMP3 and AMP4, NMOS transistors M6, M4 and M5, and capacitor C2. Resistor R4 has a value of 300 kΩ, and resistor R5 has a value 100 times greater than that of R4. Capacitor C2 has a value of 20 pF. The open-loop gain of amplifiers AMP3 and AMP4 is 80 dB.

[0044] The forward terminal of infrared photodiode VD3 is grounded, and the reverse terminal is connected to the non-inverting terminal of amplifier AMP4, the source of NMOS transistor M6, and the drain of PMOS transistor M5. The non-inverting terminal of amplifier AMP3 is connected to the drain of PMOS transistor M4, the source of PMOS transistor M5, and one end of resistor R4. The other end of resistor R4 is connected to the drain of NMOS transistor M6 and one end of resistor R5. The other end of resistor R5 is connected to one end of capacitor C1 and the gate of PMOS transistor M5. The other end of capacitor C2 is grounded. The source of PMOS transistor M4 is connected to the power supply voltage VDD. The reverse terminals of amplifier AMP3 and amplifier AMP4 are connected to the reference voltages VREF3 and VREF4, respectively. The output of amplifier AMP3 is connected to the gate of PMOS transistor M4, and the output of amplifier AMP4 is connected to the gate of NMOS transistor M6.

[0045] As the light intensity gradually increases, the photocurrent of the infrared photodiode VD3 gradually increases, the drain voltage of PMOS transistor M4 (i.e., the output voltage OUT3) gradually increases, the source voltage of PMOS transistor M5 gradually increases, and the absolute value of the gate-source voltage gradually increases. PMOS transistor M5 turns on, the photocurrent is shunted, the gate voltage of PMOS transistor M4 increases, and the absolute value of the gate-source voltage decreases, thus regulating the overall photocurrent to decrease. The drain voltage of PMOS transistor M4 (i.e., the output voltage OUT3) decreases, fluctuating within a small range to prevent distortion of small signals.

[0046] Using a remote control configured according to the above embodiments, in a typical home application scenario, the light intensity was continuously increased. When the light intensity increased to 50,000 LUX, the remote control could still operate normally, and the signal reception was good.

[0047] Based on any of the above embodiments, the inventors provide an infrared receiving chip, which is provided with an IV conversion circuit for resisting strong light interference as described in any of the above embodiments.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An IV conversion circuit resistant to strong light interference, characterized in that, The system includes an infrared photodiode VD3, resistors R4 and R5, amplifiers AMP3 and AMP4, an NMOS transistor M6, a PMOS transistor M4, a PMOS transistor M5, and a capacitor C2. The forward input of the infrared photodiode VD3 is grounded, and its reverse input is connected to the non-inverting input of amplifier AMP4, the source of NMOS transistor M6, and the drain of PMOS transistor M5. The non-inverting input of amplifier AMP3 is connected to the drain of PMOS transistor M4, the source of PMOS transistor M5, and one end of resistor R4. The other end of resistor R4... One end of the capacitor is connected to the drain of the NMOS transistor M6 and one end of the resistor R5. The other end of the resistor R5 is connected to one end of the capacitor C2 and the gate of the PMOS transistor M5. The other end of the capacitor C2 is grounded. The source of the PMOS transistor M4 is connected to the power supply voltage VDD. The inverting terminals of the amplifier AMP3 and the amplifier AMP4 are connected to the reference voltages VREF3 and VREF4, respectively. The output of the amplifier AMP3 is connected to the gate of the PMOS transistor M4, and the output of the amplifier AMP4 is connected to the gate of the NMOS transistor M6.

2. The IV conversion circuit for resisting strong light interference as described in claim 1, characterized in that, The value of resistor R4 is greater than or equal to 200KΩ and less than or equal to 300KΩ, and the value of resistor R5 is at least 100 times greater than the value of resistor R4.

3. The IV conversion circuit for resisting strong light interference as described in claim 2, characterized in that, The resistor R4 = 300KΩ.

4. The IV conversion circuit for resisting strong light interference as described in claim 3, characterized in that, The capacitor C2 is greater than 10pF.

5. The IV conversion circuit for resisting strong light interference as described in claim 3, characterized in that, The capacitor C2 has a value of 20pF.

6. The IV conversion circuit for resisting strong light interference as described in claim 4 or 5, characterized in that, The open-loop gain of amplifiers AMP3 and AMP4 is greater than 70dB.

7. The IV conversion circuit for resisting strong light interference as described in claim 4 or 5, characterized in that, The open-loop gain of amplifiers AMP3 and AMP4 is 80dB.

8. An infrared receiver chip, characterized in that, The infrared receiver chip is provided with an IV conversion circuit for resisting strong light interference as described in any one of claims 1-7.

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