A balanced self-oscillating mixer is proposed. It consists of a pair of AlGaAs/GaAs 10 x 45 mum pHEMT's, oscilliting at 7.53 GHz and uses the extended resonance effect. The circuit exhibits a conversion gain of 3.6 dB and reduces the second-order intermodulation products by 18.3 dB, The balanced nature of the oscillators also provides good LO to RF isolation of 40.5 dB when used as a upconverter. This approach relaxes the filtering requirements for generating single-sideband AM.