Generalised model for prediction and synthesis of negative capacitance at microwave frequencies using common-gate MESFET

Newly-derived equations describing the input impedance of MESFET common-gate stages are presented, allowing the synthesis of negative input capacitance using a simple MESFET circuit. Results derived from such equations show excellent agreement with those obtained using a microwave simulator, up to frequencies close to the cut-off frequency of the MESFET employed. A three-stage optical receiver front-end is used as an illustrative example to show the generation of negative capacitance under practical circuit constraints.