A transimpedance CMOS multichannel amplifier with a 50 Omega-wide output range buffer for high counting rate applications

A fast transimpedance multichannel amplifier has been designed, fabricated in CMOS 1.2-mu m technology and tested, Each channel consists of a current sensitive preamplifier followed by a voltage amplification stage and an on-chip buffer able to drive 50 Omega loads with an output range of +/-800 mV, Measured peaking time at the output is 40 ns and the circuit recovers to baseline in 90 ns, This results in a counting capability of more than 10(7) hits/s. Signals of both polarities can be handled, The first two stages consume a total of 2 mW per channel and the 50 Omega buffer consumes another 17 mW, The equivalent noise charge (ENC) is 1100 e(-) rms with a slope of 40e(-)/pF. The IC is intended for use in gas and solid-state detectors with high particle rate and extensive charge release as in high energy calorimetry.