A Wideband Delay-Tunable Fully Differential Allpass Filter in 65-nm CMOS Technology

摘要

In this paper, the generation of fully differential 2^nd order voltage-mode allpass filters is systematically studied and modeled using two-port network techniques. The proposed filters are based only on the generic two transistor common-drain differential pair and a series of surrounding RLC impedances. Five designs of possible allpass filters based on various choices of the surrounding impedances are also presented. Selected designs were verified with experimental results using discrete MOS transistors as proof of concept. One of the proposed filters was simulated in 65-nm CMOS and showed 46GHz delay-bandwidth while the delay can be electronically tuned via the bias current and independent from the pole frequency.