A 4GHz 2b 5^th Order Continuous-Time $\boldsymbol{\Delta} \boldsymbol{\Sigma}$ Modulator with –100.1dBc THD and 122DBFS SFDR in 100MHz BW

This work presents a continuous-time <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta \Sigma$</tex> modulator (CTDSM) with a novel <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5^{\text {th }}$</tex> order noise transfer function (NTF) that increases in-band SQNR by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 9.5 ~\text{dB}$</tex> compared to conventional NTFs. This allows its sampling frequency to be reduced, enabling the use of a 2b SAR quantizer, which dissipates less power than a conventional <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2 b$</tex> flash quantizer and does not require power-hungry digital offset calibration. Furthermore, its <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1^{\text {st }}$</tex> integrator is based on a single energyefficient inverter, whose limited DC gain is absorbed by the rest of the loop filter. While sampling at 4 GHz, the resulting CTDSM achieves -100.1 dBc THD, 74.5 dB SNDR over a 100 MHz BW and consumes 49.5 mW. This results in 5.6 dB higher energy-efficiency than CTDSMs with similar BW and linearity.