Correlated double-sampling program-controlled gain amplifier for high-energy particle detection pixel sensor and implementation method of correlated double-sampling program-controlled gain amplifier

Abstract

The invention provides a correlated double-sampling program-controlled gain amplifier for a high-energy particle detection pixel sensor and an implementation method, and solves the technical problem that a large dynamic range and high readout precision cannot be considered at the same time during existing high-energy particle detection. The circuit comprises a correlated double-sampling circuit, a signal polarity conversion circuit, an amplification feedback circuit and a configuration automatic judgment circuit. The correlated double sampling circuit is used for performing double sampling on the output voltage of the pixel signal to obtain twice sampling voltage; the configuration automatic judgment circuit is used for selecting configurations for switching according to the voltage difference between the two sampling voltages to obtain an output signal; and the amplification feedback circuit is used for performing fixed gain voltage amplification on the output signal to obtain an amplified voltage signal. The circuit can be widely applied to the technical field of integrated circuits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of integrated circuits, and more particularly relates to a correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor and an implementation method thereof. BACKGROUND

[0002] Monolithic active pixel sensors, relying on mature semiconductor industry technology, have been established as an important detection means for the next generation of high-energy particle detection experiments due to their good radiation resistance, extremely low mass, excellent ionization energy loss detection performance, and extremely high position resolution.

[0003] In a pixel sensor, after the front-end readout circuit acquires the particle incident signal and converts it into an electrical quantity, the electrical quantity needs to be processed at the sensor column end and output to an ADC for analog-to-digital conversion, thereby facilitating further signal output and event reconstruction. The input of this part of the readout circuit needs to be compatible with the dynamic range of the sensor front-end circuit, the output needs to be matched with the dynamic range of the subsequent ADC, and the processing speed is also a key factor in determining the sensor frame rate.

[0004] Since the reset voltage of the pixel diode in the pixel sensor is greater than the signal voltage after the accumulation of the charge, after correlated double sampling, the output signal of the CMOS pixel sensor is a single-ended negative polarity signal. In addition, the free electrons excited by the high-energy particle incident are proportional to the square of the nuclear charge number, so the difference value of the charge amount excited by adjacent high-energy particles with different nuclear charge numbers increases with the increase of the nuclear charge number of the incident particle, which means that although a high dynamic range is required to distinguish the signals of heavy particles, the quantization accuracy required to distinguish adjacent particles decreases with the increase of the nuclear charge number of the incident particle. Therefore, there is an urgent need to provide a correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor to solve the above problems. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor to solve the technical problem that the prior art cannot simultaneously consider large dynamic range and high readout accuracy during high-energy particle detection.

[0006] To achieve the above purpose, a first aspect of the embodiments of the present application provides a correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor, which comprises a correlated double sampling circuit, and further comprises a signal polarity conversion circuit, an amplification feedback circuit and a configuration automatic judgment circuit connected with the correlated double sampling circuit. The correlated double sampling circuit is used to double sample the output voltage of the pixel signal to obtain two sampling voltages. The configuration automatic judgment circuit is used for selecting configuration to switch according to the voltage difference of the two sampling voltages to obtain an output signal; when the voltage difference is higher than a preset threshold, a dynamic range expansion configuration is used to convert the pixel signal from a single-ended single-polarity signal to a differential bipolar signal through a signal polarity conversion circuit, otherwise, an equivalent circuit of a high-precision configuration is used for high-precision amplification. The amplification feedback circuit is used for fixed gain voltage amplification of the output signal to obtain an amplified voltage signal.

[0007] Preferably, the correlated double sampling circuit includes sampling capacitors C1, C2, C3 and C4, switches S1, S2, S 4.1 , S 4.2 , S 6.1 and S 6.2 , one end of the switch S1 receives an input voltage of the pixel signal, and the other end is connected to the switch S 4.1 through the sampling capacitor C1, the switch S 4.1 is connected to the positive reference voltage, and the switch S1 further leads out a wire connected to the ground through the switch S 6.1 and the sampling capacitor C4; one end of the switch S2 receives an input voltage of the pixel signal, and the other end is connected to the switch S 4.2 through the sampling capacitor C2, the switch S 4.2 is connected to the negative reference voltage, and the switch S2 further leads out a wire connected to the ground through the switch S 6.2 and the sampling capacitor C3.

[0008] Preferably, the positive input end of the configuration automatic judgment circuit is connected to the sampling capacitor C1 through a buffer, the negative input end of the configuration automatic judgment module is connected to the sampling capacitor C2 through a buffer, and the output end of the configuration automatic judgment module is connected to the switch S 6.1 and the switch S 6.2 . The configuration automatic judgment circuit includes a differential capacitor DAC and a zero threshold comparator; the differential capacitor DAC includes a first capacitor array, a second capacitor array and a PCD protection circuit, one end of the first capacitor array is connected to the PCD protection circuit, the other end of the first capacitor array is connected to the zero threshold comparator, one end of the zero threshold comparator is connected to the differential capacitor DAC, and the other end of the zero threshold comparator is connected to a logic control circuit of a subsequent ADC, and the logic control circuit is used for providing a driving signal for the configuration automatic judgment circuit by multiplexing the configuration automatic judgment circuit and the subsequent ADC.

[0009] Preferably, the signal polarity conversion circuit includes switches S 3.1 , S 3.2 , S 5.1 and S 5.2 , one end of the switch S 3.1 is connected to the sampling capacitor C1 in the correlated double sampling circuit to receive the pixel signal, and the other end of the switch S3.1 The other end of the switch S 3.2 is connected to a sampling capacitor C2 in a correlated double sampling circuit, and receives a pixel signal. 3.1 The other end of the switch S 5.1 is connected to a sampling capacitor C3 in the correlated double sampling circuit, and outputs a readout calibration signal in a differential bipolar signal. 5.2 The other end of the switch S F.1 is connected to a sampling capacitor C4 in the correlated double sampling circuit, and outputs an original readout signal in the differential bipolar signal.

[0010] Preferably, the amplification feedback circuit comprises a main amplifier, a feedback capacitor C F.2 , a feedback capacitor C F.1 , and switches S F.2 ; a positive input terminal of the main amplifier is connected to the switch S 5.1 , and receives a calibration signal in the differential bipolar signal; a negative input terminal of the main amplifier is connected to the switch S 5.2 , and receives a read signal in the differential bipolar signal; one end of the feedback capacitor C F.1 is connected to the positive input terminal of the main amplifier, and the other end is connected to a negative output terminal of the main amplifier; one end of the feedback capacitor C F.2 is connected to the negative input terminal of the main amplifier, and the other end is connected to a positive output terminal of the main amplifier; the switch S F.1 is connected across the feedback capacitor C F.1 ; the switch S F.2 is connected across the feedback capacitor C F.2 ; the negative output terminal of the main amplifier outputs an amplified voltage signal V ON ; and the positive output terminal of the main amplifier outputs an amplified voltage signal V OP .

[0011] Preferably, the equivalent circuit of the high-precision configuration comprises a reset switch R , an output switch Y , a signal switch S , a signal capacitor C S , a reset capacitor C R , and a main amplifier; one end of the signal switch S is connected to the pixel signal; one end of the reset switch R is connected to the pixel signal; the other end of the signal switch S is connected to ground through the signal capacitor C S ; and the other end of the reset switch R is connected to ground through the reset capacitor CR ground, signal switch S lead-out conductor via output switch Y connects to positive input of main amplifier, reset switch R lead-out conductor via output switch Y connects to negative input of main amplifier.

[0012] The second aspect of the embodiment provides a correlated double sampling programmable gain amplifier implementation method for a high-energy particle detection pixel sensor, applied to the correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor, and includes the following steps: double sampling the output voltage of the pixel signal to obtain two sampling voltages; selecting a configuration according to the voltage difference between the two sampling voltages to obtain an output signal; when the voltage difference is higher than a preset threshold, using a dynamic range expansion configuration to convert the pixel signal from a single-ended single-polarity signal to a differential bipolar signal through a signal polarity conversion circuit, otherwise, using an equivalent circuit of a high-precision configuration to perform high-precision amplification; performing fixed gain voltage amplification on the output signal to obtain an amplified voltage signal.

[0013] Preferably, the configuration selection according to the voltage difference between the two sampling voltages includes a sampling stage, a threshold loading stage, and a discrimination stage. In the sampling stage, the two sampling voltages are respectively buffered and loaded on both ends of the DAC in the configuration automatic judgment circuit; In the threshold loading stage, the DAC superimposes a preset threshold on the sampling voltage, completing the conversion from threshold comparison to zero-crossing comparison; In the discrimination stage, the zero threshold comparator directly compares the voltage sizes of the upper and lower branch circuits, thereby discriminating the configuration to be used.

[0014] Preferably, the process of the dynamic range expansion configuration includes: opening switches S 4.2 and S 4.1 , closing switches S 3.2 and S 3.1 , obtaining the voltage of the differential bipolar signal according to the charge redistribution principle, and superimposing the potential shift determined by the negative reference voltage and the split sampling capacitor size ratio.

[0015] Preferably, the process of high-precision amplification includes: the reset level and the signal level are time-division sampled and held in the reset capacitor C R and the signal capacitor C S , and subtraction and amplification are realized by using the main amplifier.

[0016] The application has the beneficial effects that the application provides a correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor and an implementation method. The correlated double sampling circuit is used to double sample the output voltage of the pixel signal to obtain two sampling voltages. The common-mode noise and random noise are effectively suppressed, and the signal-to-noise ratio is significantly improved. The configuration automatic judgment circuit selects the appropriate configuration to switch according to the voltage difference between the two sampling voltages. When the voltage difference is higher than the preset threshold, the dynamic range expansion configuration is used, and the signal polarity conversion circuit is used to convert the pixel signal from a single-ended single-polarity signal to a differential bipolar signal, which significantly expands the dynamic range and effectively processes the large signal greater than the preset threshold that may occur in high-energy particle detection. At a low signal level, the configuration automatic judgment circuit switches to the high-precision configuration for high-precision amplification. This flexible switching mode ensures that the amplifier can adapt to different signal intensities, while taking into account both large dynamic range and high readout precision. Finally, the output signal is amplified by the fixed gain voltage of the amplification feedback circuit to improve the quality and stability of the signal, and to ensure the accuracy and reliability of the final output voltage signal.

[0017] In summary, the application realizes the consideration of large dynamic range and high readout precision. At the same time, the amplifier combining full differential, variable configuration and programmable gain can effectively suppress common-mode interference, flexibly switch configuration structure, improve signal anti-interference ability, and has wider adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 A circuit connection schematic diagram of a correlated double sampling programmable gain amplifier for a high-energy particle detection pixel sensor provided by an embodiment of the application; Figure 2 A circuit connection diagram of a correlated double sampling circuit and a signal polarity conversion circuit provided by an embodiment of the application; Figure 3 A circuit diagram of an amplification feedback circuit provided by an embodiment of the application; Figure 4 A circuit schematic diagram of a configuration automatic judgment circuit provided by an embodiment of the application; Figure 5 An equivalent circuit diagram of a correlated double sampling programmable gain amplifier in a high-precision configuration provided by an embodiment of the application; Figure 6The waveform diagram of the output of the front-end readout signal provided by an embodiment of the present application includes signal level and reset level; Figure 7 The simulation result diagram of the unbalance error of converting the single-ended single-polarity signal into the differential bipolar signal provided by an embodiment of the present application; Figure 8 The transient simulation waveform diagram of the working process of the correlated double sampling programmable gain amplifier provided by an embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0021] The present application provides a full-differential and variable-configuration column-level correlated double sampling programmable gain amplifier and an implementation method, which can be configured as an equivalent circuit of high-precision configuration when light nuclei are incident, and amplify the signal with high precision without losing the quantization precision of the input end, thereby meeting the quantization precision requirement when the differential amount of the charge amount excited by adjacent nuclear charge number particles is small. When heavy nuclei are incident, the amplifier is configured as a dynamic range expansion configuration, a differential signal is constructed by potential translation, and the dynamic range is expanded by one time by using the bipolarity of the differential signal, thereby meeting the dynamic range requirement when the differential amount of the charge amount excited by adjacent nuclear charge number particles is large. The technical problem that the large dynamic range and high readout precision cannot be considered simultaneously is solved. At the same time, the amplifier combining full-differential, variable configuration and programmable gain can effectively suppress common-mode interference, flexibly transform the configuration structure and adjust the gain in time, improve the anti-interference ability of the signal, and has wider adaptability.

[0022] Please refer to Figure 1 The correlated double sampling programmable gain amplifier provided by an embodiment of the present application for the high-energy particle detection pixel sensor includes a correlated double sampling circuit, a signal polarity conversion circuit, an amplification feedback circuit and a configuration automatic judgment circuit connected with the correlated double sampling circuit.

[0023] The correlated double sampling circuit is used to double sample the output voltage of the pixel signal to obtain two sampling voltages.

[0024] The automatic configuration determination circuit selects and switches configurations based on the voltage difference between two sampled voltages to obtain the output signal. When the voltage difference exceeds a preset threshold, a dynamic range extended configuration is used, employing a signal polarity conversion circuit to convert the pixel signal from a single-ended unipolar signal to a differential bipolar signal. Otherwise, a high-precision configuration equivalent circuit is used for high-precision amplification. This automatic configuration determination circuit can select the configuration configuration signal for configuration switching based on the voltage obtained from dual sampling, achieving high-precision configuration during light core incidence and dynamic range extended configuration during heavy core incidence. This expands the dynamic range, resolves voltage offset introduced during capacitor array switching, and precisely adjusts the difference between signal strength and quantization accuracy requirements caused by different high-energy particle incidences.

[0025] A signal polarity conversion circuit is used to convert a signal from single-ended unipolar to differential bipolar to obtain an output signal. This application uses a signal polarity conversion circuit with capacitor switching to shift the zero point of the original signal upwards to half of a preset dynamic range, converting the unipolar signal into a bipolar signal before differential amplification. This avoids the waste of dynamic range caused by directly using a fully differential amplifier to amplify unipolar signals and solves the quantization resolution loss when high nuclear charge number particles are incident.

[0026] The amplification feedback circuit is used to amplify the output signal with a fixed gain voltage to obtain the amplified voltage signal.

[0027] Specifically, please refer to Figure 2 The signal correlation dual sampling circuit of this application includes sampling capacitors C1, C2, C3, and C4, and switches S1, S2, and S4. 4.1 Switch S 4.2 Switch S 6.1 and switch S 6.2 One end of switch S1 receives the input voltage V of the pixel signal. PIXEL The other end is connected to switch S via sampling capacitor C1. 4.1 Switch S 4.1 Connect to positive reference voltage V REFTOP Switch S1 also has a lead wire that passes through switch S 6.1 The sampling capacitor C4 is grounded; one end of switch S2 receives the input voltage V of the pixel signal. PIXEL The other end is connected to switch S via sampling capacitor C2. 4.2 Switch S 4.2 Connect to negative reference voltage V REFBOT Switch S2 also has a lead wire that passes through switch S 6.2 And the sampling capacitor C3 is grounded.

[0028] The signal polarity conversion circuit of this application includes a switch S 3.1 Switch S 3.2, switch S 5.1 and switch S 5.2 , the signal polarity conversion circuit is closely connected with the correlated double sampling circuit, and the polarity conversion is realized through the connection of switch S1, sampling capacitor C1, switch S 4.1 , switch S2, sampling capacitor C2 and switch S 4.2 . Specifically, one end of switch S 3.1 is connected with sampling capacitor C1 in the correlated double sampling circuit, and receives pixel signal V PIXEL , the other end of switch S 3.1 is grounded, one end of switch S 3.2 is connected with sampling capacitor C2 in the correlated double sampling circuit, and receives pixel signal V PIXEL , the other end of switch S 3.1 is grounded, one end of switch S 5.1 is connected with sampling capacitor C3 in the correlated double sampling circuit, and the other end outputs readout calibration signal V CALIB in the differential bipolar signal, one end of switch S 5.2 is connected with sampling capacitor C4 in the correlated double sampling circuit, and the other end outputs original readout signal V READ in the differential bipolar signal. The signal polarity conversion circuit outputs the converted differential bipolar signal V CALIB and V READ to the amplification feedback circuit.

[0029] The present application utilizes the synergistic effect of the signal polarity conversion circuit and the correlated double sampling circuit to perform potential shifting, and converts the pixel signal V PIXEL from single-ended unipolar to differential bipolar. By further splitting the sampling capacitor in the traditional correlated double sampling circuit, the variable-size sub-capacitor array in the correlated double sampling circuit is switched between the determined reference voltages. By utilizing the charge redistribution principle, a variable DC offset conversion circuit is realized, so that the sub-capacitor arrays of the same size in the upper and lower branch circuits are switched between the determined reference potentials, and the size of the sub-capacitor array is matched according to the gain selection of the correlated double sampling programmable amplifier, so as to realize the level shifting of the pixel signal according to the different amplitude of the input dynamic range of the correlated double sampling programmable amplifier, and complete the conversion of the pixel signal V PIXEL from single-ended unipolar to differential bipolar. If the reference voltages of the upper and lower branch circuits in the signal polarity conversion circuit and the correlated double sampling circuit are set to be consistent with the positive and negative reference voltages of the subsequent ADC, the signal polarity conversion circuit does not need to rely on the additional on-chip voltage source, and even when the reference voltage fluctuates, the correlated double sampling programmable gain amplifier and the subsequent ADC dynamic range can still be matched, so as to suppress the non-ideal effect caused by the power supply change, and ensure the accuracy of the pixel signal V PIXEL .

[0030] Please refer toFigure 3 , the amplification feedback circuit comprises a main amplifier, a feedback capacitor C F.1 , C F.2 , and switches S F.1 , S F.2 . The positive input end of the main amplifier is connected to the switch S 5.1 , and receives the calibration signal V CALIB in the differential bipolar signal, the negative input end of the main amplifier is connected to the switch S 5.2 , and receives the read signal V READ in the differential bipolar signal, one end of the feedback capacitor C F.1 is connected to the positive input end of the main amplifier, and the other end is connected to the negative output end of the main amplifier, one end of the feedback capacitor C F.2 is connected to the negative input end of the main amplifier, and the other end is connected to the positive output end of the main amplifier, the switch S F.1 is connected across the feedback capacitor C F.1 , and the switch S F.2 is connected across the feedback capacitor C F.2 , the negative output end of the main amplifier outputs the amplified voltage signal V ON , and the positive output end of the main amplifier outputs the amplified voltage signal V OP . During amplification of the main amplifier, the sampling capacitors C1, C2, C3 and C4 and the feedback capacitors C F.1 and C F.2 inside the amplifier constitute a negative feedback loop to obtain stable and programmable closed-loop gain. The application adopts a high-gain operational amplifier as the main amplifier, and realizes stable closed-loop gain by setting the negative feedback loop and the sampling capacitors to constitute a closed-loop negative feedback structure, so as to perform voltage amplification on the output signal with fixed gain and obtain the amplified voltage signal.

[0031] Please refer to Figure 1 , the positive input end of the configuration automatic judgment circuit is connected to the sampling capacitor C1 through a buffer, the negative input end of the configuration automatic judgment module is connected to the sampling capacitor C2 through a buffer, and the output end of the configuration automatic judgment module is connected to the switch S 6.1 and the switch S 6.2 . The configuration automatic judgment circuit is actually a programmable threshold comparator, which is composed of a differential capacitor DAC and a zero threshold comparator, and is used for judging the amplitude of the pixel signal output by the front-end readout circuit, and selecting the configuration configuration signal according to the amplitude, so as to guide the configuration automatic judgment circuit to switch the configuration, so as to meet the required low-quantization accuracy and high-dynamic range.

[0032] Specifically, the configuration automatic judgment module is multiplexed with the rear-stage ADC, and the rear-stage ADC of the application refers to a SAR-ADC (successive approximation type analog-to-digital converter). Please refer to Figure 4For the circuit principle diagram of the configuration automatic judgment circuit, the configuration automatic judgment circuit comprises a differential capacitor DAC and a zero threshold comparator. The differential capacitor DAC comprises a first capacitor array, a second capacitor array and a PCD protection circuit, one end of the first capacitor array is connected with the PCD protection circuit, the other end of the first capacitor array is connected with the zero threshold comparator, one end of the zero threshold comparator is connected with the differential capacitor DAC, and the other end of the zero threshold comparator is connected with a logic control circuit of a subsequent ADC. The logic control circuit is used for providing a driving signal for the configuration automatic judgment circuit by multiplexing the configuration automatic judgment circuit and the subsequent ADC. The first capacitor array comprises capacitors C1t-C9t, the capacitance values of which are switched by switches to realize threshold adjustment. One end of the first capacitor array is provided with a differential input signal interface for inputting VIP, VRP, VCM and VRP signals. The second capacitor array comprises capacitors C1b-C9b, the capacitance values of which are switched by switches to realize threshold adjustment. One end of the second capacitor array is provided with a differential input signal interface for inputting VIP, VRP, VCM and VRP signals. The zero threshold comparator inputs signals DAC_CTRL, clock_gate, comp_result, discri_clk, asyn_clk and DAC_CTRL. The logic control circuit inputs signals ADC_CALLB, DIACRI_SAMP, THERESHOLD_LOAD, CONFIG_DISCRT, THERESHOLD[N-1:0], ADC_SAMP and ADC_TRANS.

[0033] The configuration automatic judgment circuit in the present application adopts a high-precision configuration to amplify a pixel signal with high precision when a voltage difference is lower than a preset threshold. Please refer to Figure 5 For the equivalent circuit diagram of the correlated double sampling program-controlled gain amplifier in the high-precision configuration. The equivalent circuit of the correlated double sampling program-controlled gain amplifier in the high-precision configuration is composed of two groups of sampling and holding circuits and a main amplifier, comprising a reset switch R , an output switch Y , a signal switch S , a signal capacitor C S , a reset capacitor C R and a main amplifier. One end of the signal switch S is connected with a pixel signal V PIXEL . One end of the reset switch R is connected with a pixel signal V PIXEL . The other end of the signal switch S is connected with the ground through the signal capacitor C S . One end of the reset switch RThe other end of the reset capacitor C R Ground, signal switch S The lead-out wire is connected to the output switch Y The positive input end of the main amplifier, reset switch R The lead-out wire is connected to the output switch Y The negative input end of the main amplifier.

[0034] An embodiment of the present application provides a correlated double sampling programmable gain amplifier implementation method for a high-energy particle detection pixel sensor, comprising the following steps: S1: double sampling the output voltage of the pixel signal to obtain two sampling voltages.

[0035] After the pixel signal is read out by the front-end readout circuit, the correlated double sampling is performed. In the present application, the read READ stage sampling is taken as an example, when the lower branch circuit samples, 、 、 Closed, the remaining switches are opened. The output voltage V PIXEL of the pixel is sampled to the sampling capacitors and , and the charge quantity is shown by the following formula: ; In the formula, is the charge quantity stored on the sampling capacitor during the sampling process, is the charge quantity stored on the sampling capacitor during the sampling process, is the capacitance of the sampling capacitor , is the capacitance of the sampling capacitor , is the voltage of the output of the pixel signal, is the negative reference voltage.

[0036] After the sampling is completed, the switch is disconnected, and the sampling in the read stage is completed. Subsequently, the pixel signal is reset, and the upper and lower branch circuits of the present application are consistent. Therefore, when the lower branch circuit samples, 、 、 Closed, the remaining switches are opened, and the voltage of the pixel signal is sampled to the sampling capacitors and , to obtain the sampling capacitor 、 of the upper branch circuit and the sampling capacitor 、 .

[0037] S2: Select the configuration and switch according to the voltage difference between the two sampled voltages to obtain the output signal; when the voltage difference is higher than the preset threshold, the dynamic range extension configuration is used to use the signal polarity conversion circuit to convert the pixel signal from a single-ended unipolar signal to a differential bipolar signal; otherwise, the equivalent circuit of the high-precision configuration is used for high-precision amplification.

[0038] After sampling of both upper and lower branch circuits, the voltages of both branch circuits are sent to the automatic configuration determination circuit, which is essentially a programmable threshold comparator. The automatic configuration determination circuit determines the configuration to use based on the voltage difference between the sampling capacitors of the upper and lower branches. When the voltage difference between the upper and lower branch circuits is higher than the preset threshold, a unipolar to bipolar dynamic range extended configuration is used; otherwise, a traditional high-precision configuration is used.

[0039] Specifically, the configuration determination process in this application includes three stages: sampling (AMPSW_SAMP), threshold loading (SMPSW_DISCRI), and discrimination (AMPSW_COMP). During the sampling stage, the voltages of the upper and lower branch circuits of the relevant dual-sample programmable gain amplifier are buffered and loaded onto the two ends of the DAC in the automatic configuration determination circuit. During the threshold loading stage, the DAC superimposes a preset threshold onto the sampling voltage, completing the conversion from non-zero threshold comparison to zero threshold comparison. During the discrimination stage, the zero-threshold comparator directly compares the voltage magnitudes of the upper and lower branch circuits to determine the required configuration.

[0040] When the voltage difference exceeds a preset threshold, a dynamic range extension configuration is adopted to convert unipolar to bipolar. Taking the initial READ stage of the following branch circuit as an example, the circuit is disconnected. ,closure At this time, the upper plate of the capacitor is floating, and the stored charge is... According to the principle of charge redistribution, we have the following equation: ; In the formula, This refers to the voltage of the read signal in a differential bipolar signal. Sampling capacitor The capacitance value, Sampling capacitor The capacitance value, The output voltage of the pixel signal. This is the reference voltage.

[0041] It can be solved at this time The voltage is shown in the following formula: ; In the formula, This refers to the voltage of the read signal in a differential bipolar signal. the capacitance of the sampling capacitor, the capacitance of the sampling capacitor, the capacitance of the sampling capacitor, the capacitance of the sampling capacitor, the output voltage of the pixel signal, the negative reference voltage.

[0042] At this time, the voltage of the original readout signal in the differential bipolar signal is superimposed on the potential by the negative reference voltage and the potential shift determined by the size matching of the split sampling capacitor.

[0043] The upper half branch circuit is also disconnected , closed to perform level shifting. From the above formula, the voltage shift on the capacitor in the upper and lower branch circuits is related to the positive and negative reference voltages and respectively. Since the same size matching of the split sampling capacitor is used in the upper and lower branches, the differential term caused by the DC shift after sampling is as follows: ; In the formula, is the differential voltage introduced after the DC shift of the two sampling circuits, is the capacitance of the sampling capacitor, is the capacitance of the sampling capacitor, is the capacitance of the sampling capacitor, is the negative reference voltage, V DR is the output dynamic range of the front-end readout circuit, is the positive reference voltage.

[0044] In this application, the positive and negative reference voltages and are consistent with the reference voltages and of the subsequent ADC, and are taken , , the output dynamic range of the front-end readout circuit =400mV, and the default capacitance size relationship is .

[0045] At this point, in the single-polarity to bipolar dynamic range expansion configuration, the voltages sampled by the upper and lower plates of the related double-sampling programmable gain amplifier are subjected to different amplitude potential shifts, realizing the function of converting the single-polarity signal output by the pixel into a bipolar signal.

[0046] When the voltage difference is lower than the preset threshold, the equivalent circuit with high precision configuration is used for high precision amplification. Disconnect S 6.1 and S​6.2 At this time, the correlated double sampling programmable gain amplifier can be equivalent to a high-precision configuration circuit. Please refer to Figure 6 , which is an output waveform diagram of the front-end readout signal, wherein singal is the signal level, and reset is the reset level. When the circuit starts to work, the reset level and the signal level in the front-end readout circuit are time-divisionally sampled and held in the reset capacitor C R and the signal capacitor C S , and then the two are subtracted and amplified by using the main amplifier. The present application uses a differential operational amplifier of the order of μV~nV as the main amplifier, reduces the loss of accuracy, and ensures the accuracy of the output signal.

[0047] S3: The output signal is amplified by a fixed gain voltage to obtain an amplified voltage signal.

[0048] After the sampling and configuration switching of the correlated double sampling programmable gain amplifier are completed, S 6.1 and S 6.1 are disconnected, and S 5.1 and S 5.1 are connected. The correlated double sampling programmable gain amplifier is switched from the voltage follower configuration to the full-differential amplification configuration and performs full-differential closed-loop gain amplification, and the amplification multiple is calculated according to the charge redistribution principle and is . Among them, is the voltage amplification multiple, is the capacitor with subscript 3, is the feedback capacitor. The values of the capacitors in the circuit and the dynamic ranges and gains corresponding to the two configurations are shown in Table 1.

[0049] Table 1 Values of capacitors in CDS-PGA and corresponding dynamic ranges and gains

[0050] By changing the loaded threshold, the correlated double sampling programmable gain amplifier is configured in a dynamic range expansion configuration for transient simulation, and the introduced offset error in the dynamic range expansion configuration process is analyzed, and the results are shown in Figure 7 . The original readout READ end does not introduce offset error due to small voltage switching amplitude, and the error introduced by the CALIB end is about 0.89 mV. Since the dynamic range expansion configuration corresponding to the unipolar to bipolar mode is only enabled when the input signal amplitude is higher than the preset threshold 80 mV, and the offset error is relatively fixed for a single channel, it can be compensated by an off-chip calibration circuit, and therefore can be ignored.

[0051] The amplification multiples of the two configurations are adjusted to 6 times, and different sizes of input excitation are applied to the correlated double sampling programmable gain amplifier circuit for transient simulation. Figure 8The simulation waveforms of the correlated double sampling programmable gain amplifier twice signal processing are shown, wherein, ①~⑥ are the responses when the signal input is greater than the preset threshold, ⑦ is the response when the signal input is less than the preset threshold.

[0052] At ①, the correlated double sampling in the correlated double sampling programmable gain amplifier respectively performs the original reading READ and reading calibration CALIB twice sampling operations on the pixel signal greater than the preset threshold, to obtain the voltage obtained by twice sampling; at ②, the correlated double sampling programmable gain amplifier buffers the voltage obtained by twice sampling to the sampling circuit of the configuration automatic judgment circuit; at ③, the rear-stage ADC multiplexing for the configuration automatic judgment circuit superimposes the set programmable threshold on the voltage obtained by sampling, and compares, to output the configuration discrimination result; at ④, according to the configuration discrimination result, different amplitudes are respectively translated, to convert the single-ended single-polarity signal into a bipolar signal; at ⑤, the main amplifier performs full differential amplification on the converted bipolar signal; in addition, due to the time-sharing multiplexing of the threshold comparator and the SAR-ADC, the voltage waveform of the successive approximation analog-to-digital conversion of the comparison node can be seen at ⑥. The working processes of the correlated double sampling programmable gain amplifier at ⑦~⑨ are similar to those at ①~③. At ⑩, the correlated double sampling programmable gain amplifier adopts high-precision configuration according to the configuration discrimination result, so the correlated double sampling programmable gain amplifier does not perform voltage translation operation. Thereafter, at , the main amplifier directly performs full differential amplification on the double-sampled signal, and at , analog-to-digital conversion is performed. Both the large dynamic range and the high reading accuracy are taken into account, to ensure the accuracy of the amplified voltage signal.

[0053] Those skilled in the art can appreciate that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software mode depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0054] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A correlation-dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor, comprising a correlation-dual-sampling circuit, characterized in that, It also includes a signal polarity conversion circuit, an amplification feedback circuit, and an automatic configuration determination circuit connected to the aforementioned dual sampling circuit; The related dual sampling circuit is used to double sample the output voltage of the pixel signal to obtain two sampled voltages. The automatic configuration determination circuit is used to select and switch configurations based on the voltage difference between the two sampled voltages to obtain an output signal. When the voltage difference is higher than a preset threshold, the dynamic range extended configuration is used to convert the pixel signal from a single-ended unipolar signal to a differential bipolar signal using the signal polarity conversion circuit. Otherwise, the equivalent circuit of the high-precision configuration is used for high-precision amplification. The amplification feedback circuit is used to amplify the output signal with a fixed gain voltage to obtain an amplified voltage signal.

2. The correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 1, characterized in that, The related dual sampling circuit includes sampling capacitors C1, C2, C3, and C4, and switches S1, S2, and S4. 4.1 Switch S 4.2 Switch S 6.1 and switch S 6.2 One end of the switch S1 receives the input voltage of the pixel signal, and the other end is connected to the switch S1 via the sampling capacitor C1. 4.1 The switch S 4.1 Connected to a positive reference voltage, the switch S1 also has a lead wire extending from the switch S... 6.1 The sampling capacitor C4 is grounded; one end of the switch S2 receives the input voltage of the pixel signal, and the other end is connected to the switch S2 via the sampling capacitor C2. 4.2 The switch S 4.2 Connected to a negative reference voltage, the switch S2 also has a lead wire extending from the switch S... 6.2 The sampling capacitor C3 is grounded.

3. The correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 2, characterized in that, The positive input terminal of the automatic configuration determination circuit is connected to the sampling capacitor C1 via a buffer, the negative input terminal of the automatic configuration determination module is connected to the sampling capacitor C2 via a buffer, and the output terminal of the automatic configuration determination module is connected to the switch S. 6.1 and switch S 6.2 ; The automatic configuration determination circuit includes a differential capacitor DAC and a zero-threshold comparator. The differential capacitor DAC includes a first capacitor array, a second capacitor array, and a PCD protection circuit. One end of the first capacitor array is connected to the PCD protection circuit, and the other end of the first capacitor array is connected to the zero-threshold comparator. One end of the zero-threshold comparator is connected to the differential capacitor DAC, and the other end is connected to the logic control circuit of the subsequent ADC. The logic control circuit is used to provide a drive signal for the automatic configuration determination circuit by multiplexing the automatic configuration determination circuit with the subsequent ADC.

4. The correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 2, characterized in that, The signal polarity conversion circuit includes a switch S. 3.1 Switch S 3.2 Switch S 5.1 and switch S 5.2 The switch S 3.1 One end is connected to the sampling capacitor C1 in the related dual sampling circuit to receive the pixel signal, and the switch S 3.1 The other end of the switch is grounded, and the switch S 3.2 One end is connected to the sampling capacitor C2 in the related dual sampling circuit to receive the pixel signal, and the switch S 3.1 The other end of the switch is grounded, and the switch S 5.1 One end is connected to the sampling capacitor C3 in the related dual sampling circuit, and the other end outputs the readout calibration signal in the differential bipolar signal. The switch S 5.2 One end is connected to the sampling capacitor C4 in the related dual sampling circuit, and the other end outputs the original readout signal in the differential bipolar signal.

5. The correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 4, characterized in that, The amplification feedback circuit includes a main amplifier and a feedback capacitor C. F.1 Feedback capacitor C F.2 and switch S F.1 Switch S F.2 The positive input terminal of the main amplifier is connected to the switch S. 5.1 The main amplifier receives the calibration signal from the differential bipolar signal, and its negative input terminal is connected to the switch S. 5.2 The feedback capacitor C receives the read signal from the differential bipolar signal. F.1 One end of the capacitor is connected to the positive input terminal of the main amplifier, and the other end is connected to the negative output terminal of the main amplifier. The feedback capacitor C F.2 One end of the switch S is connected to the negative input terminal of the main amplifier, and the other end is connected to the positive output terminal of the main amplifier. F.1 Connected to the feedback capacitor C F.1 At both ends, the switch S F.2 Connected to the feedback capacitor C F.2 At both ends, the negative output terminal of the main amplifier outputs the amplified voltage signal V. ON The main amplifier outputs an amplified voltage signal V at its positive output terminal. OP .

6. The correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 5, characterized in that, The equivalent circuit of the high-precision configuration includes a reset switch. R Output switch Y Signal switch S Signal capacitor C S Reset capacitor C R and the main amplifier, the signal switch S One end is connected to the pixel signal, and the reset switch R One end is connected to the pixel signal, the signal switch S The other end is connected to the signal capacitor C S Grounding, the reset switch R The other end is connected to the reset capacitor C R Grounding, the signal switch S Lead wires pass through the output switch Y The reset switch is connected to the positive input terminal of the main amplifier. R Lead wires pass through the output switch Y Connect to the negative input terminal of the main amplifier.

7. A method for implementing a correlated double-sample programmable gain amplifier for a high-energy particle detection pixel sensor, applied to the correlated double-sample programmable gain amplifier for a high-energy particle detection pixel sensor as described in any one of claims 1-6, characterized in that, Includes the following steps: The output voltage of the pixel signal is double-sampled to obtain two sampled voltages; The configuration is switched according to the voltage difference between the two sampled voltages to obtain the output signal; when the voltage difference is higher than a preset threshold, the dynamic range extension configuration is used to convert the pixel signal from a single-ended unipolar signal to a differential bipolar signal using the signal polarity conversion circuit; otherwise, the equivalent circuit of the high-precision configuration is used for high-precision amplification. The output signal is amplified by a fixed gain voltage amplification to obtain an amplified voltage signal.

8. The method for implementing a correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 7, characterized in that, The configuration selection based on the voltage difference between the two sampled voltages includes a sampling phase, a threshold loading phase, and a discrimination phase. During the sampling phase, the two sampled voltages are respectively buffered and applied to both ends of the DAC in the automatic configuration determination circuit; During the threshold loading stage, the DAC superimposes a preset threshold onto the sampling voltage, completing the conversion from threshold comparison to zero-crossing comparison; During the discrimination phase, the zero-threshold comparator directly compares the voltage magnitudes of the upper and lower branch circuits to determine the configuration to be used.

9. The method for implementing a correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 7, characterized in that, The process of the dynamic range extension configuration includes: disconnecting switch S 4.2 and switch S 4.1 Close switch S 3.2 and switch S 3.1 The voltage of the differential bipolar signal is obtained based on the charge redistribution principle, and the potential shift is superimposed by the negative reference voltage and the ratio of the size of the split sampling capacitors.

10. The method for implementing a correlated dual-sampling programmable gain amplifier for a high-energy particle detection pixel sensor as described in claim 7, characterized in that, The high-precision amplification process includes: the reset level and the signal level being sampled and held at the reset capacitor C in a time-division manner. R and signal capacitor C S In this process, the main amplifier is used to achieve subtraction and amplification.

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