Design of Cryogenic Fully Differential Gain Boosting-OTA by the $g_{m}/I_{d}$ methodology used for a 14 bit Pipelined-SAR ADC

Quantum computing (QC) requires cryogenic electronic circuits as control and readout sub-systems of quantum chips to meet the qubit scale-up challenges.At this temperature,MOSFETs transistors exhibition many changes such as higher threshold voltage,higher mobility,and steeper substhreshold slope.We present a cryogenic fully differential gain boosting-OTA used for a 14 bit Pipelined-SAR ADC operating at 4.2K as the readout circuit for semiconductor-based quantum computing system.Using $g_{m}/I_{d}$ methodology to get pre-computed lookup tables based on the cryogenic 110nm BSIM4 model.The proposed OTA achieves very high unity-gain frequency@1.23GHz and open-loop low frequency gain@101dB.The total power consumption is 2.66mW at 4.2K,and a setting accuracy better than 0.01\% with $f_{-3dB}$ of 37MHz in a closed-loop application.