Measurements and analysis of different front-end configurations for monolithic SiGe BiCMOS pixel detectors for HEP applications

This paper presents a small-area monolithic pixel detector ASIC designed in 130 nm SiGe BiCMOS technology for the upgrade of the pre-shower detector of the FASER experiment at CERN. The purpose of this prototype is to study the integration of fast front-end electronics inside the sensitive area of the pixels and to identify the configuration that could satisfy at best the specifications of the experiment. Self-induced noise, instabilities and cross-talk were minimised to cope with the several challenges associated to the integration of pre-amplifiers and discriminators inside the pixels. The methodology used in the characterisation and the design choices will also be described. Two of the variants studied here will be implemented in the pre-production ASIC of the FASER experiment pre-shower for further tests.

A 5–50 GHz SiGe BiCMOS Linear Transimpedance Amplifier with 68 dBΩ Differential Gain towards Highly Integrated Quasi-Coherent Receivers

Quasi-coherent optical receivers have recently emerged targeting access networks, offering improved sensitivity and reach over direct-detection schemes at the expense of a higher receiver bandwidth. Higher levels of system integration together with sufficiently wideband front-end blocks, and in particular high-speed linear transimpedance amplifiers (TIAs), are currently demanded to reduce cost and scale up receiver data rates. In this article, we report on the design and testing of a linear TIA enabling high-speed quasi-coherent receivers. A shunt-feedback loaded common-base topology is adopted, with gain control provided by a subsequent Gilbert cell stage. The circuit was fabricated in a commercial 130 nm SiGe BiCMOS technology and has a bandpass characteristic with a 3 dB bandwidth in the range of 5–50 GHz. A differential transimpedance gain of 68 dBΩ was measured, with 896 mVpp of maximum differential output swing at the 1 dB compression point. System experiments in a quasi-coherent receiver demonstrate an optical receiver sensitivity of −30.5 dBm (BER = 1 × 10−3) at 10 Gbps, and −26 dBm (BER = 1 × 10−3) at 25 Gbps. The proposed TIA represents an enabling component towards highly integrated quasi-coherent receivers.