Fast CMOS binary front end for silicon strip detectors at LHC experiments

Abstract

We present design and test results of the front-end circuit developed in a 0.25 m complementary metal-oxide semiconductor technology.The aim of this work is to study the performance of a deep submicron process in applications for fast binary front ends for silicon strip detectors.The channel comprises a fast transimpedance preamplifier working with an active feedback loop, two stages of the amplifier-integrator circuits providing 22 ns peaking time, and a two-stage differential discriminator.A particular effort has been made to minimize the current and the power consumption of the preamplifier, while keeping the required noise and timing performance.For a detector capacitance of 20 pF noise below 1500 e equivalent noise charge (ENC) has been achieved for 300 A bias current in the input transistor, which is comparable with the levels achieved in the past for the front end using a bipolar input transistor.The total supply current of the front end is 600 A and the power dissipation is 1.5 mW per channel.The offset spread of the comparator is below 3 mV rms.