Common gate cross-coupled differential amplifier for near-field sensors

A differential amplifier with an input stage of a common gate cross-coupled differential type is presented. The first and the two other common source differential stages are connected via single-ended source follower type level shifting buffers. Feedback circuitry is added to compensate the offset owing to the process, temperature and supply mismatches of the transistors at the input differential stage. The amplifier is designed using OMMIC ED02AH GaAs technology having a semi-insulating substrate which is advantageous for monolithic integration of low-loss passive elements such as loops. The realised amplifier achieves a gain of greater than 28 dB over a bandwidth of 10 GHz.