A monolithic microwave integrated circuit (MMIC) semiconductor chip, for use with a hybrid coupler, in a frequency downconverter. The chip has a first input lead for receiving a first combined input signal from the coupler, a second input lead for receiving a second combined input signal from the coupler, and an output lead. Each input signal is a microwave signal combined with a further frequency signal, and one of the microwave and further frequency signals of the first combined signal is out of phase with one of the microwave and further frequency signals of the second combined signal. A single balanced mixer has a first single ended mixer for converting the first combined signal to a first intermediate frequency signal and a second single ended mixer for converting the second combined signal to a second intermediate frequency signal. An amplifier is coupled to the first and second mixers for forming an amplified unbalanced intermediate frequency (IF) signal at the output lead representative of the first and second intermediate frequency signals.