A 0.5-/0.95-dB NF, 50-/25-Ω Configurable CMOS Front-End ASIC for the Readout of Liquid Argon Calorimeter in the LHC

This article presents the design of a four-channel front-end application specific integrated circuit (ASIC), ATLAS liquid argon front-end (ALFE), developed for the readout of the liquid-argon calorimeter (LAr) detector in the ATLAS experiment at the Large Hadron Collider (LHC). ALFE enables the readout of current signals induced in the LAr with a dynamic range (DR) exceeding 16 bits, while ensuring seamless operation in a system comprising nearly 200000 channels with detector capacitances ranging from 0.16 to 2 nF per channel. Each analog front-end (AFE) channel provides configurable and matched input impedance of either 50 or $25~\Omega $ , measures an equivalent noise current (ENI) of $\mathbf {47.5}$ or $\mathbf {147.5~\text {nA}}$ , achieves sub- $\mathbf {0.2\% }$ integral non-linearity (INL) for signal peak measurement, and maintains a power supply rejection (PSR) exceeding 14 dB up to $\mathbf {1~\text {MHz}}$ . Each AFE channel incorporates a low-noise amplifier (LNA) with a noise figure (NF) of 0.5 or 0.95 dB and an input-referred voltage noise density of $ \mathbf {0.28~\text {nV}/(\text {Hz})^{1/2} }$ . This LNA is implemented with a fully-differential amplifier (FDA) enclosed in an asymmetric differential feedback (ADF), followed by a two-gain fully differential CR–RC² bandpass filter (BPF). ALFE can withstand a radiation-induced total ionizing dose (TID) exceeding 1.4 Mrad. Besides the four AFE channels, ALFE integrates an analog trigger-sum (ATS), an SEE/SEU-tolerant I²C interface, voltage and current references, and current digital-to-analog converters (DACs).