Cryogenic charge-sensitive preamplifiers, for high dynamic range and fast speed of response using GaAs technology

Charge-sensitive preamplifiers using GaAs MESFETs have been designed to satisfy requirements of high dynamic range, low power dissipation, and low noise at short shaping times. They use SGM20006M MESFETs, a replacement type for the 3SK164. The main parameters of the preamplifiers with a detector capacitance of 400 pF are an equivalent noise charge (ENC) of 5500 RMS electrons at 77 K at 100-μs Gaussian shaping time, an input resistance of 22 Ω, and a power dissipation of 52 mW with 0.2% integral nonlinearity and 2-V output. Radiation damage tests have been performed showing a fairly high ENC insensitivity to 10¹⁴n/cm² neutron fluence, particularly at short shaping time. Ionizing radiation increases the ENC by a factor of 2 when the dose is 10 Mrad(Si)