  A wide swing charge sensitive amplifier (CSA) has been developed, as a part
of a front-end electronics (FEE) readout ASIC, for a prototype silicon tungsten
(Si-W) based electromagnetic (EM) calorimeter. The CSA, designed in 0.35 $\mu$m
N-well CMOS technology using 5V MOS transistors, has a wide linear operating
range of 2.6 pC w.r.t the input charge with a power dissipation of 2.3 mW. A
noise figure (ENC) of 820 e$^-$ at 0 pF of detector capacitance with a noise
slope of 25 e$^-$/pF has been achieved (when followed by a CR-RC$^2$ filter of
1.2 $\mu$s peaking time). This design of CSA provides a dynamic range (ratio of
maximum detectable signal to noise floor) of 79 dB for the maximum input charge
of 2.6 pC when connected to a silicon detector with a capacitance of 40 pF.
Using folded cascode architecture-based input stage and low voltage high swing
current mirrors as the load, the CSA provides an enlarged output swing when
biasing the output node towards one supply rail and utilizing the voltage range
towards the opposite rail. The design philosophy works for both polarities of a
large input signal. This paper presents the design of CSA with a wide negative
output swing for an anticipated input signal of positive polarity in the target
application with a known detector biasing scheme.
