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

We present the design and the test results of a front-end circuit developed in a 0.25 μm CMOS technology. The aim of this work is to study the performance of a deep submicron process in applications for fast binary front-end 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 two-stage differential discriminator. 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^- ENC has been achieved for 300 μA bias current in the input transistor, which is comparable with levels achieved in the past for a front-end using bipolar input transistor. The total supply current of the front-end is 600 μA and the power dissipation is 1.5 mW per channel. The offset spread of the comparator is below 3 mV rms.