Simulated Channel Length Variation Effects on Regulated Cascode Input Stage-Based Transimpedance Amplifier for Fiber Optics Applications

Abstract

A proposed transimpedance amplifier with
channel length variation is simulated. The amplifier consists of
a regulated cascode input stage followed by a common gatecommon source configuration. A channel length series (45 nm,
90 nm and 130 nm) in CMOS technology was introduced
within the proposed amplifier in order to achieve comparative
performance analysis. There are two key findings from this
study. On one hand, it was found that the trade off in gain
versus bandwidth and input referred noise current still applies
when channel length is moved upward from 45 nm up to 130
nm. A series of transimpedance amplifier gains (42.16 dBΩ,
44.34 dBΩ and 46.25 dBΩ) that correspond to (1.80 GHz, 1.33
GHz and 1.06 GHz) of f-3dB bandwidths is reported
corresponding to the above channel length series respectively
with an input referred noise current spectral density series
(16.35 pA⁄√Hz, 12.17 pA⁄√Hz and 10.60 pA⁄√Hz) of reduction.
On the other hand, a reduction in power consumption occurred
as channel length is moved upward for the same proposed
topology. A total power consumption series (0.611 mW, 0.287
mW and 0.173 mW) was reported that corresponds to the
above channel length series.