A low-noise, wideband, integrated CMOS transimpedance preamplifier for photodiode applications

A low-noise, wideband, integrated CMOS transimpedance preamplifier is presented for silicon avalanche photodiode (APD) applications. The preamplifier, fabricated in a standard 2- mu m CMOS technology, features a transimpedance gain of 45 k Omega , a risetime of 22 ns, a series noise of 1.6 nV/Hz/sup 1/2/, and a wideband equivalent input-noise current of 12 nA for a source capacitance of 12 pF. The measured /sup 22/Na timing resolution of 9.2-ns FWHM and energy resolution of 22.4% FWHM for the RCA C30994 bismuth germanate (BGO)/APD detector module coupled to the preamplifier was comparable to the performance reported using charge-sensitive preamplifiers. This illustrates that transimpedance preamplifiers should be considered for APD applications, especially where APD noise current dominates noise from feedback resistors in the 10-k Omega to 50-k Omega range.<
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