High-precision assembly line ADC and front-end calibration method

Abstract

The invention discloses a high-precision assembly line ADC and a front-end calibration method. The method comprises the steps: outputting a differential mode DC input signal Vin1 to the assembly line ADC through an external signal source, storing the total digital output code Dout1 of the assembly line ADC at this time, fixing the input signal of the assembly line ADC as Vin2, storing the output code Dout2 of the assembly line ADC at this time, and subtracting the Dout1 from the Dout2; and comparing the obtained delta Dout with an output coding difference delta Dout when the input of the pipeline ADC is Vin1 and Vin2 under an ideal condition, judging the gain, and adjusting the effective feedback capacitance Cfeq of an MDAC module in the pipeline ADC according to a judgment result, thereby achieving the purpose of adjusting the gain. The method is continuously and repeatedly carried out until delta Dout is equal to delta Dout id, feedback capacitance control signals are solidified, and foreground calibration is completed. According to the method, the defects that a traditional algorithm in a high-precision assembly line ADC is complex and low in precision are overcome, algorithm logic can be achieved only through storage, subtraction, addition and comparison, and the method has the advantages of being efficient, quick and accurate and is suitable for high-speed and high-precision assembly line ADC calibration.

Description

technical field [0001] The invention belongs to the field of high-precision pipeline ADC calibration, and in particular relates to a high-precision pipeline ADC and a front-end calibration method thereof. Background technique [0002] The traditional pipeline ADC system structure is shown in Figure 1(a). The input signal is directly injected into the first pipeline sub-stage for sampling, and each pipeline sub-stage performs sampling and residual amplification alternately under the control of two-phase non-overlapping clocks. Inside each pipeline sub-stage, when sampling the phase, the multiplication digital-to-analog converter MDAC and the auxiliary analog-to-digital converter SubADC simultaneously sample the input signal and end the sampling at the same time, ensuring that the multiplication digital-to-analog converter MDAC and the auxiliary analog-to-digital converter SubADC The comparator in the sample to the same input signal point, the auxiliary analog-to-digital conve...

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Problems solved by technology

[0005] Aiming at the inadequacy of the above-mentioned prior art that cannot take into account both the gain of the operational amplifier and the speed of the operational amplifier, the present invention provides a high-precision pipeline ADC and an effective front-end calibration method, which is used to calibrate the inter-stage gain of each pipeline sub-stage of the pipeline , it is necessary to subtract the total digital output code of the ADC, and change the connection mode of the internal analog circuit of the pipeline ADC according to the calculation result to achieve the purpose of gain calibration

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