Energy Optimization for Optical Receivers Based on a Cherry-Hooper Emitter Follower Transimpedance Amplifier Front-end in 130-nm SiGe HBT Technology

We present an interpretation of conventional figure-of-merit (FOM) and average input-referred noise current density (IRNCD) that characterizes optical receivers to determine how technologies and circuits best address energy efficiency. A design methodology is presented for differential optical receivers based on Cherry-Hooper Emitter Follower (CHEF) front-end designs targeting 56-Gbps applications is realized in a 130-nm SiGe BiCMOS process. The electrical measurements in a 50-
$\Omega$
environment demonstrate data rates up to 112 Gbps and 84 Gbps for two design variants. In an open input and maximum gain configuration, the rms input referred noise currents are 3.59
$\mu$
$A_{RMS}$
and 2.41
$\mu$
$A_{RMS}$
and the corresponding average input referred noise current densities are 17.25
$pA/\sqrt{Hz}$
and 12.86
$pA/\sqrt{Hz}$
. The packaged electro-optical measurements of the receiver variants is carried out with a single commercial off-the-shelf (COTS) photodetector demonstrate open eyes at data rates up to 64 Gbps. At 60 Gbps, the receiver variants achieve a
$BER < 10^{-10}$
and
$BER < 10^{-9}$
. The total power consumption for the variants are 162 mW and 138 mW for overall energy efficiencies (with respect to electro-optical performance) of 2.53
$pJ/bit$
and 2.3
$pJ/bit$
.