CN-121643737-B - Thermal noise elimination type high-precision ADC and implementation method

CN121643737BCN 121643737 BCN121643737 BCN 121643737BCN-121643737-B

Abstract

The invention provides a thermal noise elimination type high-precision ADC and an implementation method thereof, wherein the thermal noise elimination type high-precision ADC comprises a plurality of stages of circuits connected in series, each single-stage circuit comprises a sub ADC, a DAC array, an auxiliary capacitor module and an amplifying module, the DAC array is used for sampling mixed voltage in a sampling stage, the auxiliary capacitor module is used for sampling input signals and providing static bias voltage for all capacitors in the DAC array in a noise storage stage so as to separate thermal noise voltage from the mixed voltage, the amplifying module is used for amplifying the thermal noise voltage in the noise storage stage and storing the amplified thermal noise voltage, and amplifying the amplified thermal noise voltage by utilizing the amplified thermal noise voltage and high gain characteristics in a quantization and residual amplification stage, amplifying residual signals through charge transfer according to a charge conservation principle, and taking the amplified residual signals as output voltages of the current single-stage circuit. In this way, the accuracy of the pipelined ADC is improved.

Inventors

LIU SHUBIN
Wu Deao
SHEN YUKE
ZHANG YANBO
DING RUIXUE
ZHU ZHANGMING

Assignees

西安电子科技大学

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (6)

1. A thermal noise cancellation type high-precision ADC, wherein the thermal noise cancellation type high-precision ADC comprises a plurality of stages of circuits connected in series, wherein each single stage of circuit comprises a sub ADC, a DAC array, an auxiliary capacitor module and an amplifying module; The DAC array is used for sampling mixed voltage in a sampling stage, wherein the mixed voltage comprises an input voltage and an introduced thermal noise voltage; The auxiliary capacitor module is connected with the DAC array and the sub-ADC and is used for sampling input signals and providing static bias voltage for all capacitors in the DAC array in a noise storage stage so as to separate the thermal noise voltage from the mixed voltage, and the auxiliary capacitors in the auxiliary capacitor module are used for providing the static bias voltage for all capacitors in the DAC array in the noise storage stage Is greater than the capacitance value of each capacitor in the DAC array; The amplifying module is connected with the DAC array and is used for amplifying the thermal noise voltage in the noise storage stage, storing the amplified thermal noise voltage and eliminating the thermal noise voltage by utilizing the amplified thermal noise voltage and the high gain characteristic in the quantization and residual amplification stage; the sub ADC is used for quantizing the input signal to generate a digital output code; the DAC array is further used for responding to the digital output code and switching reference voltages to generate residual signals; The amplifying module is further used for amplifying the residual signal through charge transfer according to a charge conservation principle, outputting an amplified residual signal, taking the amplified residual signal as the output voltage of the current single-stage circuit, and taking the amplified residual signal as the input signal of the next single-stage circuit; the amplifying module comprises a noise storage capacitor Feedback capacitor Capacitance Pre-amplifier High gain amplifier Switch Switch Switch And a switch ; The pre-amplifier The noise storage stage is used for amplifying the thermal noise voltage to generate the amplified thermal noise voltage; The noise storage capacitor Storing the amplified thermal noise voltage; The high gain amplifier For determining the pre-amplifier by using the amplified thermal noise voltage and the high gain characteristic in the quantization and residual amplification stage And the thermal noise voltage is compared with the voltage of the input end of the pre-amplifier The voltages at the input ends of the two filters are mutually offset to eliminate sampling thermal noise; The high gain amplifier In particular for the noise storage capacitor during the residual amplification stage Is connected in series with the pre-amplifier Is provided and the high gain amplifier Due to the high gain amplifier Is provided with a high impedance characteristic of the input terminal, the noise storage capacitor The voltage information stored thereon remains unchanged due to the high gain amplifier High gain characteristics of the high gain amplifier The voltage at the input of which is determined to be virtual ground, the pre-amplifier The voltage at the output of the (c) is also maintained constant, the pre-amplifier The voltage at the output of (2) is expressed as: ; the pre-amplifier The expression of the voltage at the input of (c) is: ; Wherein, the For the pre-amplifier Is used for the voltage at the input terminal of the (c), For the pre-amplifier Is used for the voltage at the output terminal of the (c), For the pre-amplifier Is used for the gain of (a), In order to sample the charge of the thermal noise, Is the first of the DAC arrays The capacitance value of the individual capacitors is determined, For the total capacitance value of all capacitances in the DAC array, For the amplified thermal noise voltage; In the residual amplification stage, the digital output code generated by the sub-ADC controls the reference voltage connected to the DAC array, and according to the principle of conservation of charge, the expression of the output voltage of the current single-stage circuit of the thermal noise cancellation type high-precision ADC is: ; Wherein, the For the output voltage of the present single stage circuit, Is the first of the DAC arrays The capacitance value of the individual capacitors is determined, For the total capacitance value of all capacitances in the DAC array, For the input voltage to be described, For the reference voltage to be used, The digital output code is used to output a digital output code, For the feedback capacitance A corresponding capacitance value; and if no sampling thermal noise component exists in the expression of the output voltage of the current single-stage circuit, the sampling thermal noise is eliminated from the output of the single-stage circuit of the thermal noise elimination type high-precision ADC.
2. The thermal noise cancellation type high-precision ADC of claim 1, wherein said auxiliary capacitance module comprises said auxiliary capacitance And a switch The auxiliary capacitor Bottom plate and common mode voltage of (c) Connection of the auxiliary capacitor Top plate of (c) and said switch Is connected with one end of the DAC array, and the switch And the other end of the DAC array is connected with one end of the sub ADC and the other end of the DAC array.
3. The thermal noise cancellation type high precision ADC of claim 2, wherein said DAC array comprises a plurality of sub-DAC cells connected in parallel, each sub-DAC cell comprising a first switch Second switch Third switch Fourth switch And a first capacitor The first switch One end of (2) is connected with the switch Is connected with one end of the sub ADC, the first switch Is connected with the fourth switch at the other end Is connected with the first capacitor Is connected with the second switch Is connected with the third switch Is connected with one end of the fourth switch Is connected with the auxiliary capacitor at the other end Top pole plate of (c), the switch Is connected with one end of the first capacitor Is connected with one end of the amplifying module, the second switch And the other end of (2) is connected with positive reference voltage Is connected with the third switch And the other end of (2) is connected with negative reference voltage And (5) connection.
4. The thermal noise cancellation type high-precision ADC of claim 3, wherein said switch One end of (2) common mode voltage Connection, the switch Is arranged at the other end of the first capacitor Is arranged at the other end of the pre-amplifier Is connected to the input terminal of the feedback capacitor Is connected to the end point X, the pre-amplifier And the noise storage capacitor Is connected with one end of the noise storage capacitor Is connected with the other end of the high gain amplifier Is connected with the switch Is connected with one end of the switch Is connected with the common mode voltage at the other end Connection, the high gain amplifier And the output end of the capacitor Top plate of the output voltage Said switch Is connected with one end of the capacitor Bottom plate of (2) is grounded, the switch Is connected with the feedback capacitor at the other end Is connected with the switch Is connected with one end of the switch Is connected with the common mode voltage at the other end And (5) connection.
5. The thermal noise cancellation type high-precision ADC of claim 1, wherein said thermal noise voltage is expressed as: ; Wherein, the For the said thermal noise voltage to be present, For the input voltage to be described, As the total charge on the DAC array, Is the first of the DAC arrays The capacitance value of the individual capacitors is determined, For the total capacitance value of all capacitances in the DAC array, To sample the charge of thermal noise.
6. A method for implementing a thermal noise cancellation type high-precision ADC, which is applicable to the thermal noise cancellation type high-precision ADC according to any one of claims 1 to 5, comprising: in a sampling phase, sampling a mixed voltage, the mixed voltage comprising an input voltage and an introduced thermal noise voltage; sampling an input signal and providing a static bias voltage to all capacitors in the DAC array during a noise storage phase to separate the thermal noise voltage from the mixed voltage; amplifying the thermal noise voltage in the noise storage stage, and storing the amplified thermal noise voltage; In the quantization and residual amplification stage, eliminating the thermal noise voltage by utilizing the amplified thermal noise voltage and high gain characteristics; quantizing the input signal to produce a digital output code; switching a reference voltage to generate a residual signal in response to the digital output code; Amplifying the residual signal through charge transfer according to a charge conservation principle, outputting an amplified residual signal, taking the amplified residual signal as the output voltage of a current single-stage circuit, and taking the amplified residual signal as the input signal of a next single-stage circuit; the step of eliminating the thermal noise voltage by utilizing the amplified thermal noise voltage and the high gain characteristic in the quantization and residual amplification stage comprises the following steps: In the quantization and residual amplification stage, determining the voltage of the input end of the pre-amplifier by utilizing the amplified thermal noise voltage and the high gain characteristic; The thermal noise voltage and the voltage of the input end of the pre-amplifier are mutually counteracted to eliminate sampling thermal noise; in the quantization and residual amplification stage, the voltage at the input end of the pre-amplifier is determined by using the amplified thermal noise voltage and the high gain characteristic, and the thermal noise voltage and the voltage at the input end of the pre-amplifier are mutually offset to eliminate sampling thermal noise, which comprises the following steps: in the residual amplifying stage, the noise storage capacitor Is connected in series with the pre-amplifier Is provided and the high gain amplifier Due to the high gain amplifier Is provided with a high impedance characteristic of the input terminal, the noise storage capacitor The voltage information stored thereon remains unchanged due to the high gain amplifier High gain characteristics of the high gain amplifier The voltage at the input of which is determined to be virtual ground, the pre-amplifier The voltage at the output of the (c) is also maintained constant, the pre-amplifier The voltage at the output of (2) is expressed as: ; the pre-amplifier The expression of the voltage at the input of (c) is: ; Wherein, the For the pre-amplifier Is used for the voltage at the input terminal of the (c), For the pre-amplifier Is used for the voltage at the output terminal of the (c), For the pre-amplifier Is used for the gain of (a), In order to sample the charge of the thermal noise, Is the first of the DAC arrays The capacitance value of the individual capacitors is determined, For the total capacitance value of all capacitances in the DAC array, For the amplified thermal noise voltage; In the residual amplification stage, the digital output code generated by the sub-ADC controls the reference voltage connected to the DAC array, and according to the principle of conservation of charge, the expression of the output voltage of the current single-stage circuit of the thermal noise cancellation type high-precision ADC is: ; Wherein, the For the output voltage of the present single stage circuit, Is the first of the DAC arrays The capacitance value of the individual capacitors is determined, For the total capacitance value of all capacitances in the DAC array, For the input voltage to be described, For the reference voltage to be used, The digital output code is used to output a digital output code, For the feedback capacitance A corresponding capacitance value; and if no sampling thermal noise component exists in the expression of the output voltage of the current single-stage circuit, the sampling thermal noise is eliminated from the output of the single-stage circuit of the thermal noise elimination type high-precision ADC.

Description

Thermal noise elimination type high-precision ADC and implementation method Technical Field The present invention relates to the field of integrated circuit design, and in particular, to a thermal noise cancellation type high-precision Analog-to-Digital Converter (ADC) and a method for implementing the same. Background The pipeline ADC is widely applied to scenes such as communication systems, medical equipment, test instruments and the like which have requirements on speed and precision. The pipeline ADC realizes high-efficiency analog-to-digital conversion through a multi-stage cascade structure, and each stage of cascade structure transfers residual error to the next stage of cascade structure for continuous processing after being amplified while finishing quantization, so that balance among high sampling rate, high precision and power consumption is achieved. At present, two non-overlapping first clock signals and second clock signals exist in a single-stage circuit of a traditional pipeline ADC, when the first clock signal is at a high level, the single-stage circuit of the traditional pipeline ADC samples an input signal, when the second clock signal is at a high level, a sub ADC in the single-stage circuit quantizes the input signal to obtain a quantized result, a Digital output code corresponding to the quantized result is utilized to control a Digital-to-Analog Converter (DAC) array in the single-stage circuit to feed back, the input signal and the quantized result are subtracted, the residual obtained by subtraction is amplified to obtain an amplified residual signal, and an output end of the single-stage circuit outputs the amplified residual signal. However, due to the influence of electronic thermal motion, sampling operation can introduce sampling thermal noise to influence the quality of amplified residual signals, so that the precision of a single-stage circuit of a traditional pipelined ADC is lower. Disclosure of Invention The embodiment of the invention aims to provide a thermal noise elimination type high-precision ADC and an implementation method thereof, which solve the problem of lower precision of a single-stage circuit of a traditional pipelined ADC. In order to solve the technical problems, the embodiment of the invention provides the following technical scheme: the first aspect of the present invention provides a thermal noise cancellation type high-precision ADC comprising a series-connected multi-stage circuit, wherein each single-stage circuit comprises a sub-ADC, a DAC array, an auxiliary capacitance module and an amplification module; A DAC array for sampling a mixed voltage including an input voltage and an introduced thermal noise voltage in a sampling stage; An auxiliary capacitor module connected with the DAC array and the sub-ADC for sampling input signals and providing static bias voltage for all capacitors in the DAC array during noise storage stage to separate thermal noise voltage from mixed voltage, and auxiliary capacitor in the auxiliary capacitor module The capacitance value of each capacitor in the DAC array is larger than the capacitance value of each capacitor in the DAC array; the amplifying module is connected with the DAC array and used for amplifying the thermal noise voltage in a noise storage stage, storing the amplified thermal noise voltage and eliminating the thermal noise voltage by utilizing the amplified thermal noise voltage and high gain characteristics in a quantization and residual amplification stage; A sub ADC for quantizing an input signal to generate a digital output code; the DAC array is also used for responding to the digital output code and switching the reference voltage to generate a residual signal; the amplifying module is also used for amplifying the residual signal through charge transfer according to the principle of charge conservation, outputting the amplified residual signal, taking the amplified residual signal as the output voltage of the current single-stage circuit, and taking the amplified residual signal as the input signal of the next single-stage circuit. The second aspect of the present invention provides a method for implementing a thermal noise cancellation type high-precision ADC, including: In the sampling stage, sampling a mixed voltage, wherein the mixed voltage comprises an input voltage and an introduced thermal noise voltage; Sampling the input signal and providing a static bias voltage to all capacitors in the DAC array during a noise storage phase to separate out a thermal noise voltage from the mixed voltage; amplifying the thermal noise voltage in a noise storage stage, and storing the amplified thermal noise voltage; In the quantization and residual amplification stage, the amplified thermal noise voltage and high gain characteristic are utilized to eliminate the thermal noise voltage; Quantizing the input signal to produce a digital output code; Switching the reference voltage to generate a residual sig