Profile: Key Design Electronics Ltd. is a manufacturer of electronic products for all market sectors from aerospace to industrial, medical, and consumer products using state of the art semiconductor technology. Our services include trans impedance, amplifier, Bias generator, and CMOS comparator. Our discrete trans impedance amplifier circuit is used for amplifying PIN or avalanche photodiode (APD) signals. It uses a GaAsFET (low noise PHEMT - pseudomorphic high electron mobility transistor) as a source follower, bipolar cascade amplifier, and long tailed pair combination for low noise, high gain, and low input bias current. This allows the trans impedance (current to voltage ratio) to be very high, around 3.2M ohms or 130dB (3.2mV/nA).