Ambient and cryogenic temperature testing of a 32-channel CMOS multiplexer

A 32 channel CMOS multiplexer was tested at room temperature and at liquid helium temperature (4.9 K). Voltage gain of the FET input stage, leakage current, electrical crosstalk, and noise as a function of clock frequency were measured. The voltage gain measured at 4.9 K was slightly higher than that measured at 300 K and was independent of clock frequency at both operating temperatures. The off channel leakage current was 0.23 pA/channel at 4.9 K. Electrical crosstalk between adjacent channels (one on, one off) was quite low. The spot noise at 10 Hz, of the CMOS multiplexer operating in the static mode did not vary significantly with operating temperature. In the dynamic mode (3.2 kHz clock) at room temperature, the spot noise at 10 Hz was substantially higher than that measured in the static mode.