A new concept: an electronically tunable MMIC flatness corrector

A novel concept resulting in a good insertion gain flatness in receiver applications is reported. The idea is based on inserting into a chain a device with an attenuation characteristic equal and opposite to the gain variation of the rest of the chain. An electronically tunable flatness corrector composed of coupled lines controlled by varactors has been realized in the Ku-band. This idea has been applied in a hybrid circuit used in a space telecommunications receiver. Insertion losses of 0.25 dB, dynamic correction of 1.5 dB, and input/output return losses of better than 15 have been measured. >