A Refinement Ramp Generator for Two-Step Single-Slope Analog-to-Digital Converter

Abstract

The invention belongs to the technical field of analog-to-digital conversion, and in particular relates to a fine-grained ramp generator for a two-step single-slope analog-to-digital converter. The present invention solves the problem of integral non-linearity (INL) and differential non-linearity (INL) of the ramp generator due to changes in the common-mode level of the output buffer of the ramp generator during the establishment of the ramp generator by adopting a mode invariant to the common mode of the output buffer module 205. Linearity (DNL), spurious-free dynamic range (SFDR) and other performance degradation problems; and at the same time avoid the problem of using substrate-source short circuit to introduce substrate parasitic capacitance into the loop, which is helpful for improving the output signal of the ramp generator The linearity has a good effect; also by adopting a feed-forward transconductance path structure and a resistor-capacitor compensation structure, the purpose of pole-zero cancellation of the output buffer module 205 of the refinement ramp generator is realized, and the refinement is optimized. The linearity, loop stability and settling time of the ramp generator output buffer module 205 are quantized.

Description

technical field [0001] The invention belongs to the technical field of analog-to-digital conversion, and in particular relates to a fine-grained ramp generator for a two-step single-slope analog-to-digital converter. Background technique [0002] The slope generator (Single-Slope Generator) is essentially a digital-to-analog converter (DAC, DigitaltoAnalog Converter). Digital-to-analog conversion is to convert the digital signal processed by the system into an analog signal; input a set of digital signals to the digital-to-analog converter The corresponding analog signal is generated by accumulating the weight value of the digital signal by using the reference voltage. A digital-to-analog converter (DAC) plays an important role in converting digital signals into analog signals in the field of image sensing. DAC is currently divided into Nyquist type and oversampling type according to the principle; Nyquist type DAC is mainly divided into resistance type DAC, switched capaci...

AI Technical Summary

Problems solved by technology

[0008] For above-mentioned existence problem or deficiency, in order to solve the change of output buffer common-mode level in the existing refinement ramp generator, the unfavorable influence to the conversion performance of ramp generator; The fine-grained ramp generator of the analog-to-digital converter, whose output buffer adopts the current-current negative feedback structure, uses the fixed low-level VFB voltage (a fixed low level provided externally) as the stable common-mode voltage of the output buffer op-amp connected to its positive input

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