A new CMOS current mode fast folding amplifier

Folding amplifiers are the key building blocks of folding flash analog to digital converters (ADC). Although, there are many folding amplifiers found in the literature, their transfer characteristics are either sinusoidal or triangular which causes digitization error and needs corrective measurements in folding-amplifier based ADCs. In this work, a new CMOS current-mode folding amplifier with saw-tooth transfer characteristics is proposed. The design is based on MOS operating in strong inversion. The functionality of the proposed circuit was confirmed using Tanner T-spice in TSMC 0.18μm technology. The worst case delay of the folding amplifier is found to be 25ns which is around 10 times faster than the most recent work found in the literature.