CN115824274A - Photodetection circuit and optoelectronic system - Google Patents
Photodetection circuit and optoelectronic system Download PDFInfo
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Abstract
The embodiment of the application discloses optical detection circuit and optoelectronic system, optical detection circuit includes photoelectric conversion circuit, front end amplifier, clamp circuit and temperature drift compensation circuit, photoelectric conversion circuit has voltage bias end and the signal output part that is used for inserting bias voltage, front end amplifier has the amplification input and amplifies the output, it connects in first node with signal output part to amplify the input, clamp circuit has clamp input and clamp output, the clamp input is used for inserting clamp voltage, the clamp output is connected in first node, temperature drift compensation circuit has compensation input and compensation output, the compensation input is used for inserting temperature signal, the compensation output is connected with the clamp input and is used for exporting compensation voltage. The design can enable the bias voltage given to the two ends of the PN junction in the clamping circuit to be equal to the actual voltage drop of the PN junction, so that the PN junction in the clamping circuit works stably, and the overall stability of the optical detection circuit and the photoelectric system is further enhanced.
Description
Technical Field
The present application relates to the field of optoelectronic technologies, and in particular, to an optical detection circuit and an optoelectronic system.
Background
A signal amplifying circuit is designed in a photoelectric detection system such as a laser radar detection system or an infrared detection system, the dynamic range of the signal amplifying circuit in the current photoelectric detection system is insufficient, when the energy carried by light reflected by a target object is too large, the signal amplifying circuit is in a saturated state, when the signal amplifying circuit is in the saturated state, signals cannot be amplified normally, the photoelectric detection system is in a blind area state incapable of being detected, the saturation recovery time (namely the time for recovering from the saturated state to the linear amplification state) of the signal amplifying circuit is too long, and the photoelectric detection system is in a blind area state incapable of being detected continuously for a long time.
Disclosure of Invention
The embodiment of the application provides a light detection circuit and a photoelectric system, which can enable the bias voltage given to two ends of a PN junction in a clamping circuit to be equal to the actual voltage drop of the PN junction, so that the PN junction in the clamping circuit works stably, and the overall stability of the light detection circuit is enhanced.
In a first aspect, an embodiment of the present application provides a light detection circuit; the optical detection circuit comprises a photoelectric conversion circuit, a front-end amplifier, a clamping circuit and a temperature drift compensation circuit, wherein the photoelectric conversion circuit is provided with a voltage offset end and a signal output end which are used for accessing bias voltage, the front-end amplifier is provided with an amplification input end and an amplification output end, the amplification input end and the signal output end are connected to a first node, the clamping circuit is provided with a clamping input end and a clamping output end, the clamping input end is used for accessing clamping voltage, the clamping output end is connected to the first node, the temperature drift compensation circuit is provided with a compensation input end and a compensation output end, the compensation input end is used for accessing temperature signals, and the compensation output end is connected with the clamping output end and is used for outputting compensation voltage.
According to the optical detection circuit, the temperature signal is connected to the compensation input end of the temperature drift compensation circuit, the temperature drift compensation circuit converts the temperature signal into compensation voltage, the compensation voltage is output from the compensation output end of the temperature drift compensation circuit and flows in through the clamping input end of the clamping circuit to compensate the clamping circuit, and therefore the temperature signals corresponding to the clamping circuit at various temperatures can be made to correspond to the compensation voltage after being processed by the temperature drift compensation circuit, the compensation voltage acts on the clamping input end of the clamping circuit, the offset voltage given to the two ends of the PN junction in the clamping circuit can be equal to the actual voltage drop of the PN junction, the work of the PN junction in the clamping circuit is stable, and the overall stability of the optical detection circuit is enhanced.
In some embodiments, the temperature drift compensation circuit includes an operational amplifier, a first resistor, and a second resistor, wherein the inverting input terminal of the operational amplifier is connected to the reference voltage, a first end of the first resistor is connected to the compensation input terminal, a second end of the first resistor and the non-inverting input terminal of the operational amplifier are connected to a second node, a first end of the second resistor is connected to the second node, and a second end of the second resistor is connected to the output terminal of the operational amplifier and to the compensation output terminal.
Based on the above embodiment, the compensation input end of the temperature drift compensation circuit is connected to a temperature signal, the amplification factor of the operational amplifier can be set by adjusting the resistance values of the first resistor and the second resistor, the output end of the operational amplifier can obtain the compensation voltage corresponding to the temperature signal, after the compensation voltage is connected to the clamping input end of the clamping circuit, the bias voltage given to the two ends of the PN junction in the clamping circuit can be equal to the actual voltage drop of the PN junction, so that the clamping circuit is correspondingly provided with a compensation voltage after being processed by the temperature drift compensation circuit at different temperatures, the compensation voltage enables the PN junction in the clamping circuit to work stably, and the overall stability of the optical detection circuit is further enhanced.
In some embodiments, the temperature drift compensation circuit includes a controller having a compensation input terminal and a compensation output terminal, and the controller pre-stores a corresponding relationship between the temperature signal and the compensation voltage.
Based on the above embodiment, the temperature drift compensation circuit obtains the temperature signal through the controller, the controller obtains the corresponding compensation voltage according to the received temperature signal, and after the temperature drift compensation circuit is output through the compensation output end of the controller and flows into the clamping input end of the clamping circuit, the bias voltage given to the two ends of the PN junction in the clamping circuit can be equal to the actual voltage drop of the PN junction, so that the clamping circuit corresponds to a compensation voltage after being processed by the controller at different temperatures, and the compensation voltage enables the PN junction in the clamping circuit to work stably, thereby enhancing the overall stability of the optical detection circuit.
In some of these embodiments, the clamping circuit includes a diode having a cathode connected to the clamping output and an anode connected to the clamping input.
Based on the above embodiment, the compensation voltage output by the compensation output terminal of the temperature drift compensation circuit acts on the anode of the diode, so that the bias voltages at the two ends of the PN junction in the diode are equal to the actual voltage drop of the PN junction, and therefore the diode has a compensation voltage corresponding to different temperatures, and the compensation voltage enables the PN junction in the diode to work stably, thereby enhancing the overall stability of the light detection circuit.
In some of these embodiments, the clamping circuit comprises a transistor having a base and a collector coupled to the clamping input, and an emitter coupled to the clamping output.
Based on the above embodiment, the compensation voltage outputted from the compensation output terminal of the temperature drift compensation circuit acts on the base of the triode, so that the bias voltages at the two ends of the PN junction between the base and the emitter of the triode are equal to the actual voltage drop of the PN junction, and therefore, the triode has a corresponding compensation voltage at different temperatures, and the compensation voltage makes the PN junction between the base and the emitter of the triode work stably, thereby enhancing the overall stability of the optical detection circuit.
In some embodiments, the clamping circuit further comprises a third resistor, a fourth resistor and a first capacitor, the third resistor is connected in series between the clamping input terminal and the base of the transistor, the fourth resistor is connected in series between the clamping input terminal and the collector of the transistor, a first plate of the first capacitor is connected to the clamping input terminal, and a second plate of the first capacitor is grounded.
Based on the embodiment, the third resistor is designed, so that the current limiting effect on the current flowing into the base electrode of the triode can be realized, and the triode can be well protected; the fourth resistor is designed, so that the current flowing into the collector of the triode can be limited, and the triode can be well protected; through designing the first capacitor, the compensation voltage in the clamping circuit can be filtered, so that the stability of the compensation voltage in the clamping circuit is ensured.
In some embodiments, the clamp circuit includes a field effect transistor, a gate and a drain of the field effect transistor are connected to the clamp input terminal, and a source of the field effect transistor is connected to the clamp output terminal.
Based on the above embodiment, the compensation voltage output by the compensation output terminal of the temperature drift compensation circuit acts on the gate of the field effect transistor, so that the bias voltages at the two ends of the PN junction between the gate and the source in the field effect transistor are equal to the actual voltage drop of the PN junction, and therefore the field effect transistor has a compensation voltage corresponding to different temperatures, and the compensation voltage enables the PN junction between the gate and the source in the field effect transistor to work stably, thereby enhancing the overall stability of the optical detection circuit.
In some embodiments, the photoelectric conversion circuit includes a photodiode, a fifth resistor, and a second capacitor, a cathode of the photodiode is connected to the signal output terminal, a first terminal of the fifth resistor is connected to the voltage bias terminal, a second terminal of the fifth resistor and an anode of the photodiode are connected to the third node, a first plate of the second capacitor is connected to the third node, and a second plate of the second capacitor is grounded.
Based on the above embodiment, by connecting the anode of the photodiode to the voltage bias terminal and applying a reverse bias voltage to the photodiode through the voltage bias terminal, the photodiode is in a reverse breakdown mode under a negative bias mode, and at this time, the photodiode can not only convert the optical signal reflected by the target object into a photocurrent signal, but also amplify the photocurrent signal, and the gain amplification factor is about 100; the fifth resistor is designed to play a role in current limiting so as to protect the photodiode; the second capacitor is designed to filter the electric signal in the photoelectric conversion circuit.
In some embodiments, the front-end amplifier includes an amplifier and a sixth resistor, the amplifier is a transimpedance amplifier or a low noise amplifier, a non-inverting input terminal of the amplifier is connected to the amplifying input terminal, an inverting input terminal of the amplifier is grounded, a first terminal of the sixth resistor is connected to the output terminal of the amplifier, and a second terminal of the sixth resistor is grounded.
Based on the above embodiment, by designing the amplifier as a transimpedance amplifier, the transimpedance amplifier can amplify the current signal output via the signal output terminal of the photoelectric conversion circuit into a larger voltage signal for output, and at this time, the signal output to the subsequent circuit of the photoelectric system by the transimpedance amplifier is a voltage signal. In a similar way, by designing the amplifier into a low-noise amplifier, the electric signal output by the signal output end of the photoelectric conversion circuit can be converted into a larger electric signal, and the low-noise amplifier can amplify the effective signal in the electric signal by multiple without amplifying the noise part in the electric signal, so that the influence of the noise signal on the amplified electric signal can be effectively reduced. Through designing the sixth resistor, the sixth resistor plays a current limiting role in larger electric signals output from the output end of the amplifier, and therefore the stability of the circuit structure of the front-end amplifier is guaranteed.
In a second aspect, an embodiment of the present application provides an optoelectronic system, where the optoelectronic system includes a controller, an optical signal transmitting circuit and an optical signal receiving circuit, the optical signal transmitting circuit is electrically connected to the controller, the optical signal receiving circuit includes an analog-to-digital converter, an amplifying circuit and the optical detection circuit, and the amplifying output ends of the controller, the analog-to-digital converter, the amplifying circuit and the front-end amplifier are sequentially connected.
Based on the optoelectronic system in the embodiment of the application, the optoelectronic system with the optical detection circuit has the advantages that the compensation voltage acts on the clamping input end of the clamping circuit, so that the bias voltage given to the two ends of the PN junction in the clamping circuit is equal to the actual voltage drop of the PN junction, the PN junction in the clamping circuit works stably, and the overall stability of the optoelectronic system is further enhanced.
Based on this application embodiment's light detection circuit and optoelectronic system, temperature signal is inserted to temperature drift compensation circuit's compensation input, temperature drift compensation circuit converts this temperature signal into compensation voltage, this compensation voltage is followed temperature drift compensation circuit's compensation output and is inputed through clamper input end of clamper, compensate clamper, so can make clamper all correspond a compensation voltage after temperature drift compensation circuit handles under each temperature, this compensation voltage acts on behind clamper input end of clamper, can make the bias voltage who gives PN junction both ends in the clamper equal to the actual voltage drop of PN junction, thereby make the PN junction job stabilization in the clamper, and then strengthen this light detection circuit's overall stability.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a block diagram of a photodetection circuit according to an embodiment of the present application;
FIG. 2 is a circuit diagram of a photo detection circuit according to an embodiment of the present application;
FIG. 3 is a block diagram of a temperature drift compensation circuit according to another embodiment of the present application;
FIG. 4 is a circuit diagram of a photodetection circuit according to another embodiment of the present application;
fig. 5 is a schematic diagram of a frame of an optoelectronic system according to an embodiment of the present application.
Reference numerals are as follows: 1. a light detection circuit; 10. a photoelectric conversion circuit; 101. a voltage bias terminal; 102. a signal output terminal; 20. a front-end amplifier; 201. an amplifying input end; 202. amplifying the output end; 30. a clamp circuit; 301. a clamp input; 302. a clamp output end; 40. a temperature drift compensation circuit; 401. a compensation input terminal; 402. a compensation output end; c1, a first capacitor; c2, a second capacitor; r1 and a first resistor; r2 and a second resistor; r3 and a third resistor; r4, a fourth resistor; r5 and a fifth resistor; r6 and a sixth resistor; z1, a photodiode; z2, a triode; q1, a field effect transistor; u11, an amplifier; u12, an operational amplifier; b1, a first node; b2, a second node; b3, a third node; HV, bias voltage; v _ BAIS, clamp voltage; t, temperature signals; v +, reference voltage; 2. a controller; 21. a transmission control terminal; 22. receiving a control end; 3. an analog-to-digital converter; 4. an amplifying circuit; 5. a driving chip; 6. a light emitter; 7. a reverse bias power supply regulation circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Referring to fig. 1-2, a first aspect of the present application provides a light detection circuit 1, where the light detection circuit 1 includes a photoelectric conversion circuit 10, a front-end amplifier 20, a clamping circuit 30, and a temperature drift compensation circuit 40.
As shown in fig. 1, the photoelectric conversion circuit 10 is configured to receive light reflected by a target object and convert an optical signal of the light into an electrical signal, and the photoelectric conversion circuit 10 includes a voltage bias terminal 101 and a signal output terminal 102, where the voltage bias terminal 101 is configured to receive a bias voltage HV. The electrical signal may be a voltage signal or a current signal, and the signal output terminal 102 may be understood as a port for outputting the electrical signal in the photoelectric conversion circuit 10, and the specific circuit structure of the photoelectric conversion circuit 10 will be described below.
It should be noted that when the light reflected by the target object carries a large amount of light energy, the light can form a large electrical signal after being processed by the photoelectric conversion circuit 10; similarly, when the light reflected by the target object has a small amount of light energy, the light can form a small electrical signal after being processed by the photoelectric conversion circuit 10. That is, the light energy carried by the light reflected by the target object is in positive correlation with the electrical signal processed by the photoelectric conversion circuit 10, and the positive correlation may be linear or non-linear. The photoelectric conversion circuit 10 may have a certain electric signal amplification function.
The front-end amplifier 20 is configured to amplify the electrical signal output by the signal output terminal 102, and the front-end amplifier 20 has an amplification input terminal 201 and an amplification output terminal 202, where the amplification input terminal 201 and the signal output terminal 102 are connected to the first node b1. Here, the amplifying input terminal 201 may be understood as a port of the front-end amplifier 20 for receiving the electrical signal output by the signal output terminal 102, and the amplifying output terminal 202 may be understood as a port of the front-end amplifier 20 for outputting a larger electrical signal. The specific circuit configuration of the front-end amplifier 20 will be described later. In addition, the amplification input terminal 201 can also be connected to a subsequent signal processing circuit to realize the detection function of the optoelectronic system.
It should be noted that the electrical signal output via the signal output terminal 102 may be a voltage signal, and the voltage signal may be converted into a larger voltage signal or a larger current signal after being processed by the front-end amplifier 20 and output from the amplified output terminal 202; of course, the electrical signal output through the signal output terminal 102 may also be a current signal, and the current signal may be converted into a larger voltage signal or a larger current signal after being processed by the front-end amplifier 20 and output from the amplifying output terminal 202.
As shown in fig. 1, the clamping circuit 30 is used for reducing the electric signal flowing into the amplifying input terminal 201 of the front-end amplifier 20, the clamping circuit 30 has a clamping input terminal 301 and a clamping output terminal 302, the clamping input terminal 301 is used for connecting the clamping voltage V _ BAIS, and the clamping output terminal 302 is connected to the first node b1. It should be noted that the clamp voltage V _ BAIS can be realized by connecting the clamp input terminal 301 to a power supply or an operational amplifier, and the clamp voltage V _ BAIS can also be realized to be adjustable.
It can be understood that, if the photoelectric conversion circuit 10 detects a strong light and outputs an excessively large electrical signal to the front-end amplifier 20, that is, inputs an excessively large energy to the signal amplification circuit 20, at this time the signal amplification circuit 20 will be in a saturated state, and the larger the energy input to the signal amplification circuit 20 is, the longer the time that the signal amplification circuit 20 needs to release the energy is, that is, the longer the time that the signal amplification circuit 20 is in the saturated state is, therefore, in this embodiment of the application, by providing the clamping circuit 30, the voltage of the electrical signal output to the signal amplification circuit 20 by the photoelectric conversion circuit 10 is clamped at a required lower voltage, so as to reduce the energy output to the signal amplification circuit 20 by the photoelectric conversion circuit 10, and thus shorten the time that the signal amplification circuit 20 is in the saturated state. The specific circuit structure of the clamp circuit 30 will be described later.
It can be understood that the clamp circuit 30 has a clamp function through an internal PN junction, the PN junction itself has a conduction threshold at normal temperature, and the conduction threshold of the PN junction shifts along with the change of the temperature of the environment where the clamp circuit 30 is located, which is referred to as temperature drift for short, so that the situation that the conduction threshold of the PN junction rises or falls due to the temperature change occurs, and the overall performance of the optical detection circuit 1 is further affected.
As shown in fig. 2-3, the temperature drift compensation circuit 40 can be used to solve the problem that the voltage drop of the PN junction in the clamp circuit 30 is shifted due to the temperature change, the temperature drift compensation circuit 40 has a compensation input terminal 401 and a compensation output terminal 402, the compensation input terminal 401 is used for receiving the temperature signal T, and the compensation output terminal 402 is connected to the clamp input terminal 301 and is used for outputting the compensation voltage. The compensation input 401 may be understood as a receiving port of the temperature signal T currently in the temperature drift compensation circuit 40, and the compensation output 402 may be understood as an output port of the compensation voltage. For example, the turn-on threshold of the PN junction of the clamp circuit 30 is 0.7V at normal temperature, and as the temperature of the operating environment rises, for example, the temperature of the operating environment rises to 30 degrees celsius, the actual voltage drop of the PN junction of the clamp circuit 30 becomes 0.6V, and if the bias voltage applied to the two ends of the PN junction by the clamp circuit 30 is still 0.7V at this time, the operation of the PN junction of the clamp circuit 30 is unstable, which affects the overall performance of the optical detection circuit 1. The compensation voltage is input to the clamp circuit 30 through the temperature drift compensation circuit 40, so that the bias voltage given to two ends of the PN junction in the clamp circuit 30 is reduced to 0.6V, and the bias voltage is equal to the actual voltage drop of the PN junction by 0.6V, namely when the compensation voltage is finally applied to the PN junction, the bias voltage at two ends of the PN junction is reduced by 0.7V-0.6V =0.1V, and the bias voltage at two ends of the PN junction is equal to the actual voltage drop of the PN junction.
For another example, in cold seasons or regions, since the operating environment temperature is reduced, for example, the operating environment temperature is reduced to 15 degrees celsius, the actual conduction threshold value of the PN junction of the clamp circuit 30 becomes 0.8V, and at this time, the conduction threshold value of the PN junction of the clamp circuit 30 is increased (compared to 0.7V at normal temperature), and the bias voltage acting on both ends of the PN junction is still 0.7V, so that the PN junction of the clamp circuit 30 cannot be conducted, and the clamping function of the clamp circuit 30 cannot be realized, thereby affecting the overall performance of the light detection circuit 1. The compensation voltage is input to the clamp circuit 30 through the temperature drift compensation circuit 40, so that the bias voltages given to two ends of the PN junction in the clamp circuit 30 are equal to the actual voltage drop of the PN junction, that is, when the compensation voltage is finally applied to the PN junction, the bias voltages at two ends of the PN junction are increased by 0.8V-0.7v =0.1v, so that the voltage at two ends of the PN junction is converted from the original 0.7V to 0.7v +0.1v =0.8v, the actual conduction threshold of the PN junction is reached, the PN junction can be normally conducted, and the bias voltages at two ends of the PN junction are equal to the actual voltage drop of the PN junction, and the bias voltages at two ends of the PN junction are not too high or too low compared with the actual voltage drop of the PN junction, so that the stability of the optical detection circuit 1 during operation can be ensured.
Based on the optical detection circuit 1 in the embodiment of the present application, the photoelectric conversion circuit 10 is configured to convert a received optical signal into an electrical signal, and output the electrical signal to the signal amplification circuit 20 for amplification, and at the same time, the clamping circuit 30 is connected to the amplification input end 201 of the signal amplification circuit 20, so as to prevent the photoelectric conversion circuit 10 from inputting excessive energy to the signal amplification circuit 20 and making the signal amplification circuit 20 in a saturation state for a long time, thereby shortening the detection time of the optical detection circuit 1.
Specifically, the specific circuit structure of the temperature drift compensation circuit 40 can be implemented in, but not limited to, the following several possible embodiments.
As shown in fig. 1-2, in an embodiment, the temperature drift compensation circuit 40 includes an operational amplifier U12, a first resistor R1 and a second resistor R2, an inverting input terminal of the operational amplifier U12 is connected to the reference voltage V +, a first end of the first resistor R1 is connected to a compensation input terminal 401 of the temperature drift compensation circuit 40, a second end of the first resistor R1 and a non-inverting input terminal of the operational amplifier U12 are connected to a second node b2, a first end of the second resistor R2 is connected to the second node b2, and a second end of the second resistor R2 is connected to an output terminal of the operational amplifier U12 and to a compensation output terminal 402 of the temperature drift compensation circuit 40. In this design, the compensation input end 401 of the temperature drift compensation circuit 40 is connected to the temperature signal T, the amplification factor of the operational amplifier U12 can be set by adjusting the resistance values of the first resistor R1 and the second resistor R2, the output end of the operational amplifier U12 can obtain the compensation voltage corresponding to the temperature signal T, after the compensation voltage is connected to the clamp input end 301 of the clamp circuit 30, the clamp circuit 30 can be made to have a compensation voltage at different temperatures, the compensation voltage can make the bias voltage given to the two ends of the PN junction in the clamp circuit 30 equal to the actual voltage drop of the PN junction, so that the PN junction in the clamp circuit 30 works stably, and further the overall stability of the optical detection circuit 1 is enhanced.
For example, in fig. 2, R1=500 Ω and R2=130 Ω, taking the temperature sensor with model number TMP235A4DCKR as an example, the relationship of the output voltage of the temperature sensor with temperature change is: VT =500+10x, and when x =25 ℃, VT =750mV, V _ BAIS =3250mV.
From the above, the following relations can be obtained according to the principles of "virtual short" and "virtual break":
v3= V +. Cnlationgraph (1)
(VT-V +)/R1 = (V3-V _ BAIS)/R2
Obtaining a relation (3) according to the relation (1) and the relation (2):
V_BAIS＝((R1+R2)/R1)*(V+)-(R2/R1)*VT......(3)
substituting "x =25 ℃, VT =500+10x =500+10 + 25= 750mv" into relation (3) may reversely deduce that V _ BAIS =3250mV satisfies relation (4):
v _ BAIS =3455-0.26VT
Wherein VT is the output voltage of the temperature sensor; x is the temperature in centigrade (namely, the output voltage of the temperature sensor is increased by 10mV when the temperature is increased by 1 ℃ every time); v3 is the voltage of the non-inverting input end of the operational amplifier; v + is a reference voltage; V-BAIS is a clamping voltage; r1 is the resistance value of the first resistor; and R2 is the resistance value of the second resistor.
As shown in fig. 3, in another embodiment, the temperature drift compensation circuit 40 includes a controller, the controller has a compensation input terminal 401 and a compensation output terminal 402 of the temperature drift compensation circuit 40, and the controller pre-stores the corresponding relationship between the temperature signal T and the compensation voltage, for example, the controller is integrated with a storage unit, and the corresponding relationship between the temperature signal T and the compensation voltage is pre-stored in the storage unit. In the design, after the controller receives the temperature signal T, the controller obtains a corresponding compensation voltage according to the received temperature signal T and the corresponding relationship between the pre-stored temperature signal T and the compensation voltage, and outputs the compensation voltage to the clamping input end 301 of the clamping circuit 30 through the compensation output end 402 of the controller, so that the offset voltage given to the two ends of the PN junction in the clamping circuit 30 is equal to the actual voltage drop of the PN junction, and therefore, the clamping circuit 30 corresponds to a compensation voltage at different temperatures, and the compensation voltage enables the PN junction in the clamping circuit 30 to work stably, thereby enhancing the overall stability of the optical detection circuit 1. It will be appreciated that there is a one-to-one correspondence between the temperature signal T and the compensation voltage, e.g., the compensation voltage may decrease as the temperature signal T increases.
The clamp circuit 30 clamps the voltage by the principle of unidirectional PN junction conduction to reduce the voltage signal or energy input to the front-end amplifier 20, and the specific circuit structure of the clamp circuit 30 may be, but is not limited to, the following several possible embodiments.
In the first embodiment, the clamping circuit 30 includes a diode (not shown), the cathode of the diode is connected to the clamping output terminal 302, and the anode of the diode is connected to the clamping input terminal 301. In the design, the compensation voltage output by the compensation output terminal 402 of the temperature drift compensation circuit 40 acts on the anode of the diode, so that the bias voltage at the two ends of the PN junction of the diode is equal to the actual voltage drop of the PN junction, and therefore, the diode has a compensation voltage corresponding to different temperatures, and the compensation voltage makes the PN junction in the diode work stably, thereby enhancing the overall stability of the light detection circuit 1.
As shown in fig. 2, in the second embodiment, the clamping circuit 30 includes a transistor Z2, and the transistor Z2 is an NPN transistor for example, in this case, the base and the collector of the transistor Z2 are connected to the clamping input terminal 301, and the emitter of the transistor Z2 is connected to the clamping output terminal 302. In the design, the compensation voltage output by the compensation output terminal 402 of the temperature drift compensation circuit 40 acts on the base electrode of the triode Z2, so that the bias voltage at two ends of the PN junction between the base electrode and the emitter electrode of the triode Z2 is equal to the actual voltage drop of the PN junction, and the triode Z2 has a corresponding compensation voltage at different temperatures, and the compensation voltage enables the PN junction in the triode Z2 to work stably, thereby enhancing the overall stability of the optical detection circuit 1. Of course, the transistor Z2 may also be a PNP transistor, in which case the base and emitter of the transistor Z2 are connected to the clamping input terminal 301, and the collector of the transistor Z2 is connected to the clamping output terminal 302.
It is understood that the transistor Z2 is further connected to a voltage for turning on the transistor Z2, which voltage can be defined as a turn-on voltage, the turn-on voltage is inputted to the clamping input terminal 301 to act on the base of the transistor Z2, so as to turn on the transistor Z2, and in order to avoid burning out the transistor Z2 by the turn-on voltage and the corresponding current, the clamping circuit 30 further comprises a third resistor R3, a fourth resistor R4 and a first capacitor C1, the third resistor R3 is connected in series between the clamping input terminal 301 and the base of the transistor Z2, the fourth resistor R4 is connected in series between the collector of the transistor Z2, the first plate of the first capacitor C1 is connected to the clamping input terminal 301, and the second plate of the first capacitor C1 is grounded. In the design, the third resistor R3 is designed, so that the current flowing into the base electrode of the triode Z2 can be limited, and the triode Z2 can be well protected; the fourth resistor R4 is designed, so that the current flowing into the collector of the triode Z2 can be limited, and the triode Z2 can be well protected; by designing the first capacitor C1, the on-state voltage and the compensation voltage input to the clamp circuit 30 can be filtered, so that the stability of the clamp circuit 30 during operation can be ensured.
For example, when the transistor Z2 is a Si tube, at normal temperature, the conduction threshold of the PN junction between the base of the transistor Z2 and the emitter of the transistor Z2 is 0.7V, but when the temperature of the environment where the transistor Z2 is located rises by a certain value, for example, 30 ℃, the actual conduction threshold of the PN junction between the base of the transistor Z2 and the emitter of the transistor Z2 is also 0.6V, and if the bias voltage applied to both ends of the PN junction between the base of the transistor Z2 and the emitter of the transistor Z2 is still 0.7V at this time, the PN junction of the transistor Z2 is unstable in operation, so that the overall performance of the optical detection circuit 1 is affected. The temperature drift compensation circuit 40 inputs compensation voltage to the triode Z2, so that the bias voltage at two ends of the PN junction between the base and the emitter of the triode Z2 is reduced to 0.6V, and the bias voltage is equal to the actual voltage drop of the PN junction by 0.6V.
As shown in fig. 4, in the third embodiment, the clamping circuit 30 includes a field effect transistor Q1, and the field effect transistor Q1 is taken as a PMOS transistor for illustration, in which case, the gate and the drain of the field effect transistor Q1 are connected to the clamping input terminal 301, and the source of the field effect transistor Q1 is connected to the clamping output terminal 302. In the design, the compensation voltage output by the compensation output terminal 402 of the temperature drift compensation circuit 40 acts on the gate of the field effect transistor Q1, so that the bias voltages at the two ends of the PN junction between the gate and the source of the field effect transistor Q1 are equal to the actual voltage drop of the PN junction, and therefore the field effect transistor Q1 has a compensation voltage corresponding to different temperatures, and the compensation voltage makes the PN junction between the gate and the source of the field effect transistor Q1 work stably, thereby enhancing the overall stability of the light detection circuit 1.
It should be noted that, when the clamping circuit 30 includes a diode or a field effect transistor Q1, in order to avoid the diode or the field effect transistor Q1 from being damaged due to an excessive conducting voltage or current of the diode or the field effect transistor Q1, a current limiting resistor may be connected in series between the anode of the diode and the clamping input terminal 301, and a filter capacitor may be connected in series between the ground and the clamping input terminal 301; alternatively, a current-limiting resistor is connected in series between the gate of the fet Q1 and the clamp input terminal 301, another current-limiting resistor is connected in series between the drain of the fet Q1 and the clamp input terminal 301, and a filter capacitor is connected in series between ground and the clamp input terminal 301. Of course, the fet Q1 may also be an NMOS transistor, and in this case, the gate and the source of the fet Q1 are connected to the clamp input terminal 301, and the drain of the fet Q1 is connected to the clamp output terminal 302.
As shown in fig. 2, in view of the fact that the photoelectric conversion circuit 10 is used for converting an optical signal reflected by a target object into an electrical signal, in order to make the photoelectric conversion circuit 10 have a function of converting the photoelectric signal, the photoelectric conversion circuit 10 further includes a photodiode Z1, a fifth resistor R5 and a second capacitor C2, a cathode of the photodiode Z1 is connected to the signal output terminal 102, a first end of the fifth resistor R5 is connected to the voltage bias terminal 101, a second end of the fifth resistor R5 and an anode of the photodiode Z1 are connected to the third node b3, a first plate of the second capacitor C2 is connected to the third node b3, and a second plate of the second capacitor C2 is grounded. The photodiode Z1 may be an avalanche photodiode APD or other type of photodiode, among others. In the design, when the photodiode Z1 is an avalanche photodiode APD, the anode of the photodiode Z1 is connected to the voltage bias terminal 101, and a reverse bias voltage is applied to the photodiode Z1 through the voltage bias terminal 101, so that the photodiode Z1 is in a reverse breakdown mode, and at this time, the photodiode Z1 can not only convert an optical signal reflected by a target object into a photocurrent signal, but also amplify the photocurrent signal, and the gain amplification factor is about 100; by designing the fifth resistor R5, the fifth resistor R5 plays a role of current limiting to protect the photodiode Z1; by designing the second capacitor C2, the second capacitor C2 filters the electric signal in the photoelectric conversion circuit 10.
As shown in fig. 2, in order to make the front-end amplifier 20 have the function of amplifying the related electrical signal, the front-end amplifier 20 is further designed to include an amplifier U11 and a sixth resistor R6, the amplifier U11 is a transimpedance amplifier or a low noise amplifier, the non-inverting input terminal of the amplifier U11 is connected to the amplifying input terminal 201, the inverting input terminal of the amplifier U11 is grounded, the first terminal of the sixth resistor R6 is connected to the output terminal of the amplifier U11, and the second terminal of the sixth resistor R6 is grounded, so that the front-end amplifier 20 can amplify the electrical signal output by the signal output terminal 102 into a larger electrical signal. In the design, the amplifier U11 is designed as a transimpedance amplifier TIA, which can amplify the current signal output by the signal output terminal 102 into a larger voltage signal for output, at this time, the signal output by the transimpedance amplifier TIA to the subsequent circuit of the optoelectronic system is a voltage signal, and the transimpedance amplifier TIA has a larger amplification factor, so that the current signal output by the optoelectronic conversion circuit 10 can be amplified into a larger voltage signal. Similarly, the amplifier U11 is designed as a low-noise amplifier, which can convert the electrical signal output via the signal output terminal 102 into a larger electrical signal, and can amplify the effective signal of the electrical signal without amplifying the noise part of the electrical signal, thereby effectively reducing the influence of the noise signal on the amplified electrical signal. By designing the sixth resistor R6, the sixth resistor R6 plays a role of current limiting for a larger electrical signal output from the output terminal of the amplifier U11, thereby ensuring stability of the circuit structure of the front-end amplifier 20.
Referring to fig. 5, a second aspect of the present application provides an optoelectronic system, which includes a controller 2, an optical signal transmitting circuit and an optical signal receiving circuit, wherein the optical signal transmitting circuit is electrically connected to the controller 2, the optical signal receiving circuit includes an analog-to-digital converter 3, an amplifying circuit 4 and the optical detection circuit 1, and the controller 2, the analog-to-digital converter 3, the amplifying circuit 4 and the amplifying output terminal 202 are sequentially connected. The optoelectronic system can be a laser optoelectronic system or an infrared optoelectronic system. In this design, the optoelectronic system having the above optical detection circuit 1 has the compensation voltage applied to the clamp input terminal 301 of the clamp circuit 30, so that the bias voltage applied to the two ends of the PN junction in the clamp circuit 30 is equal to the actual voltage drop of the PN junction, thereby stabilizing the operation of the PN junction in the clamp circuit 30 and further enhancing the overall stability of the optoelectronic system.
Specifically, as shown in fig. 5, the controller 2 includes a transmission control terminal 21 and a reception control terminal 22, and the optical signal transmission circuit includes the driver chip 5 and the optical transmitter 6. The light emitter 6 may be, for example, a gallium nitride laser emitter or an infrared emitter, wherein the controller 2 controls the driving chip 5 to operate through the emission control end 21, the driving chip controls the light emitter 6 to emit corresponding laser or infrared light, the laser or infrared light is reflected by a target object, received by the photoelectric conversion circuit 10, amplified by the front-end amplifier 20, and then output to the amplifying circuit 4 for further amplification, and the analog-to-digital converter 4 is used for converting an analog signal output by the amplifying circuit 4 into a digital signal and sending the digital signal to the reception control end 22 of the controller 2, so as to implement a light detection function; further, the controller 2 is connected to the photoelectric conversion circuit 10 via the reverse bias power supply adjusting circuit 7 to adjust the bias voltage HV input to the photoelectric conversion circuit 10.
The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the present application, it is to be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and are not to be construed as limitations of the present patent, and specific meanings of the above terms may be understood by those skilled in the art according to specific situations.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A light detection circuit, the light detection circuit comprising:
the photoelectric conversion circuit is provided with a voltage bias end for accessing bias voltage and a signal output end;
a front-end amplifier having an amplification input terminal and an amplification output terminal, the amplification input terminal and the signal output terminal being connected to a first node;
the clamping circuit is provided with a clamping input end and a clamping output end, the clamping input end is used for connecting clamping voltage, and the clamping output end is connected to the first node;
the temperature drift compensation circuit is provided with a compensation input end and a compensation output end, the compensation input end is used for connecting a temperature signal, and the compensation output end is connected with the clamping input end and is used for outputting compensation voltage.
2. A light detection circuit as defined in claim 1, wherein the temperature drift compensation circuit comprises:
the inverting input end of the operational amplifier is connected with a reference voltage;
a first resistor, a first end of which is connected to the compensation input end, and a second end of which is connected to a second node together with the non-inverting input end of the operational amplifier;
a second resistor, a first end of the second resistor being connected to the second node, and a second end of the second resistor being connected to the output end of the operational amplifier and to the compensation output end.
3. A light detection circuit as defined in claim 1, wherein the temperature drift compensation circuit comprises:
and the controller is provided with the compensation input end and the compensation output end, and the controller prestores the corresponding relation between the temperature signal and the compensation voltage.
4. A light detection circuit as in claim 1, wherein the clamping circuit comprises:
a diode having a cathode connected to the clamp output terminal and an anode connected to the clamp input terminal.
5. A light detection circuit as in claim 1, wherein the clamping circuit comprises:
and the base electrode and the collector electrode of the triode are connected to the clamping input end, and the emitting electrode of the triode is connected to the clamping output end.
6. The light detection circuit of claim 5, wherein the clamp circuit further comprises:
the third resistor is connected between the clamping input end and the base electrode of the triode in series; (ii) a
The fourth resistor is connected between the clamping input end and the collector of the triode in series;
and a first polar plate of the first capacitor is connected to the clamping input end, and a second polar plate of the first capacitor is grounded.
7. A light detection circuit as in claim 1, wherein the clamping circuit comprises:
and the grid electrode and the drain electrode of the field effect transistor are connected to the clamping input end, and the source electrode of the field effect transistor is connected to the clamping output end.
8. A light detection circuit as defined in claim 1, wherein the photoelectric conversion circuit comprises:
a photodiode having a cathode connected to the signal output terminal;
a fifth resistor, a first end of the fifth resistor being connected to the voltage bias terminal, a second end of the fifth resistor and an anode of the photodiode being connected to a third node;
a second capacitor having a first plate connected to the third node and a second plate connected to ground.
9. A light detection circuit as in any one of claims 1-8, wherein the front-end amplifier comprises:
the amplifier is a trans-impedance amplifier or a low-noise amplifier, the non-inverting input end of the amplifier is connected to the amplifying input end, and the inverting input end of the amplifier is grounded;
a sixth resistor, a first end of the sixth resistor being connected to the output of the amplifier, a second end of the sixth resistor being connected to ground.
10. An optoelectronic assembly, comprising:
a controller;
the optical signal transmitting circuit is electrically connected with the controller;
an optical signal receiving circuit comprising an analog-to-digital converter, an amplifying circuit and the optical detection circuit according to any one of claims 1 to 9, wherein the controller, the analog-to-digital converter, the amplifying circuit and the amplified output of the front-end amplifier are connected in sequence.
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