Linearised 2 GHz amplifier for IMT-2000

Under large signal conditions, amplifiers using GaAs FETs have high input non-linearity due to the non-linear gate-to-source capacitance C/sub gs/ which will result in AM-PM distortion. The method presented uses a parallel connected varactor diode to linearise a GaAs FET amplifier. A reduction of 10 dB in spectral regrowth at 2 GHz is achieved with a low loss. This method is suitable for circuit miniaturisation and can be applied to amplifiers for IMT-2000.