FLAME — a readout ASIC for a compact electromagnetic calorimeter

Abstract This paper presents the design and measurement results of FLAME ( F ca L A sic for M ultiplane r E adout), a 32-channel, very low-power front-end Application-Specific Integrated Circuit (ASIC) developed for compact electromagnetic calorimeters in future particle physics experiments. FLAME, fabricated in 130 nm CMOS technology, features an analogue front-end followed by a 10-bit Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC) in each channel, and two fast data serializers (1 per 16 channels), achieving a total power consumption of only 3.13 mW per channel. The analogue front-end consists of a switchable gain preamplifier with pole-zero cancellation and a fully differential CR-RC shaper with a peaking time of 55 ns. The ultra low-power 10-bit SAR ADC works at a sampling rate of 20 MSps with a power consumption below 0.35 mW per channel. The performance of ASICs was characterised with and without sensors, demonstrating good linearity (within 2% in the linear part of the dynamic range) and an Equivalent Noise Charge (ENC) slightly above 1500 electrons with an input capacitance of 20–30 pF. The test beam results of energy deposition in a 500 μm thick silicon sensor agree with the Landau-Gauss distribution. The FLAME shows a significant reduction in power consumption compared to the older System-on-Chip (SoC) type ASICs with similar functionalities, making it a suitable candidate as a readout ASIC for future high energy physics applications.