A small area charge sensitive readout chain with a dual mode of operation

A charge sensitive readout chain has been designed and fabricated in a comm ercially available 0.8 mum CMOS technology. The readout chain is optimized for pixel detectors measuring soft X-ray energies up to 20 KeV. In the firs t mode an analog signal proportional to input charge is generated and proce ssed in real time. In the second mode a peak-and-hold operation is enabled and the relevant signal is processed in later time. This dual mode of opera tion is controlled by an external digital signal. The readout chain consist s of a charge amplifier, a shaper, an operational amplifier which can eithe r operate as a voltage amplifier or a peak detector and an output buffer. I ts area is 270 mum 150 mum. The gain at the shaper output is 378 mv/fC, the ENC is 16 e(-) rms at 160 nsec shaping time. The overall gain is 557 mV/fC , the ENC is 13 e(-) rms with 240 nsec peaking time and 1.4 mu sec recovery time. The overall power dissipation is 1.5 mWatt with a load capacitance o f 25 pF.