A 28 nm CMOS Triple-Latch Feed-Forward Dynamic Comparator With <27 ps / 1 V and <70 ps / 0.6 V Delay at 5 mV-Sensitivity
Athanasios T. Ramkaj, Marcel Pelgrom, Michiel Steyaert, Filip Tavernier
Abstract
This article presents a fully dynamic latched comparator with a high-gain three-stage configuration and an extra parallel feed-forward path, able to achieve a delay of 26.8 ps and a data rate of 13.5 Gb/s with less than 10−12 BER for a 5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\text {V}_{\text {pp}}$ </tex-math></inline-formula> differential input ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta V_{\textrm {I}}$ </tex-math></inline-formula> ) at 0.5 V common-mode ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\textrm {CM}}$ </tex-math></inline-formula> ) and 1V supply ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\textrm {DD}}$ </tex-math></inline-formula> ). Additionally, the reduced-stacking cascaded triple-latch arrangement enables a < 70ps delay down to 0.6 V <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\textrm {DD}}$ </tex-math></inline-formula> . The comparator is analyzed and compared against two prior art circuits by means of derived delay and noise expressions, serving as design guidelines. The prototype comparator and its prior art are fabricated in 28 nm bulk CMOS, with delay, input-referred noise, energy/comparison, and area measurements highlighting the benefits and trade-offs of the proposed solution.