Wide bandwidth receiver linearisation

This paper presents a way of correcting distortions due to the non-linear transfer functions of the components used in RF receivers. The technique is based on estimating the Amplitude-to-Amplitude (AM-AM) and Amplitude-to-Phase (AM-PM) distortions of the amplifier. These estimates are then fed to a postdistorter that generates inverse distortions to reduce the non-linear effect of the amplifier and hence improves the dynamic range of the receiver. The wide bandwidths which are now readily available from low-cost radio frequency amplifiers mean that it is now reasonable to make the assumption that the distortion is independent of the time-history of the signals, and assumption which is necessary in order to be able to implement this technique. The effectiveness of the method is tested experimentally. The results obtained demonstrate a third order intermodulation distortion (IMD) suppression of 40 dB and fifth order IMD suppression of 30 dB.