Characterizing sampling aperture of clocked comparators

Abstract

Practical simulation and measurement methods based on impulse sensitivity functions to characterize the sampling aperture of clocked comparators are demonstrated on a 90 nm CMOS testchip. The results comparing a StrongARM latch and a CML latch suggest that the StrongARM latch has a narrower aperture of 23 ps but its aperture center is more sensitive to supply (65 ps/V). The CML latch has a higher sampling gain of 88.8 dB but a lower bandwidth of 6.8 GHz.