A low-power high-gain transresistance BiCMOS pulse amplifier for capacitive detector readout

A low-power, high-gain amplifier for detector readout is discussed. The amplifier is balanced, fully differential in circuit topology, and symmetrical in layout, making it radiation tolerant and relatively insensitive to varying magnetic fields in the large detector. Before irradiation, the circuit has a measured differential gain of 110 mV/4 fC, an average 10/90% rise time t/sub 10/90%/ of 19 ns, a noise figure of 433/spl oplus/93/spl middot/(C/sub t/)/sup 1.08/ electrons, e/sup -/, and a power consumption of 750 /spl mu/W. To keep the core amplifier stable, a low-power super-low gain-bandwidth (SL-GBW) amplifier with a small area is used and also discussed. The SL-GBW amplified has a transition frequency f/sub T/ of 38 kHz (including the gain stage, A), a power consumption of 150 nW, a phase margin (PM) of /spl ap/70/spl deg/, an area of 300/spl times/36 /spl mu/m/sup 2/, and a minimum current per transistor of 7 nA, which is far above the leakage current after irradiation. The complete circuit was implemented in the radiation hard SOI-SIMOX BiCMOS-PJFET technology of DMILL.