A Zoom ADC Based on Time-Division Multiplexing SAR ADC
To achieve higher signal-to-noise ratio and area efficiency with limited hardware overhead,a dynamic zoom ADC based on time-division multiplexed SAR ADC is proposed.Meanwhile,a passive implementation scheme for extracting coarse quantized analog residues and feedforward is proposed,which does not require the design of an active summing operational amplifier,avoids the attenuation of common passive summing signals,and reduces the"fuzz"caused by coarse quantization noise leakage.The overall circuit is designed in two parts:coarse quantization and fine quantization.Coarse quantization is realized by a 3 bit asynchronous SAR ADC,and fine quantization is realized by a second-order 3 bit sigma-delta mo-dulator.Based on 0.18 μm CMOS technology,3.3 V supply voltage,1 MHz sampling frequency,and 1 kHz bandwidth,the current consumption is 76 µA,and the specific values of signal-to-noise distortion ratio and FOM are obtained,verifying the feasibility of the design.
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