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To take advantage of the compactness of avalanche photodiode (APD) arrays, low-noise power-efficient fast charge-sensitive preamplifier chips with differential current drivers have been developed. A 16-channel and a single-channel version are available. The chips were adapted for low-capacitance 4/spl times/8 APD arrays produced by Hamamatsu, Japan. A mixed junction field-effect transistor (JFET)-CMOS production process yielded high-quality integrated JFETs for the input stage of the amplifier's folded cascade. Thus, the 1/f-noise corner is kept at 4 kHz. The JFET has a transconductance of 11 mS at a drain current of 3 mA. The serial noise of the input transistor was found to be 0.8 nV//spl radic/(Hz). The signal rise time of the driver outputs is 20 ns. The rms noise of the preamplifier was found to be 480 e/sup -/ with a 25 e/sup -//pF noise slope for a shaping time of 50 ns. The serial input noise of the preamplifier is about 1.4 nV//spl radic/(Hz) from 200 kHz up to 40 MHz, and the 1/f-noise corner is at 70 kHz. The power consumption is 30 mW per preamplifier, including the differential driver. The linearity is better than 1.3% over 48 dB dynamic range. For the 16-channel chip, the channel-to-channel gain variation is less than 3.5%. Performance similar to photomultiplier tubes can be achieved with APDs in combination with this integrated preamplifier chip.
Date of Publication: Dec. 2001