ANALOGUE AND DIGITAL SIGNAL PROCESSING

摘要

A power amplifier (PA) in linearised by predistorting its input signal using a digital card. The output of the digital card is upconverted to RF and supplied to the amplifier. In order to be predistorted, the amplifier input signal is downconverted if it is provided at RF. The local oscillator signals used in the frequency conversion of the amplifier input signal and the clock signals used in the digital card are derived from the same master oscillator so that they are coherent. This coherency is beneficial in that, for example, it reduces the number and spread of spurious mixing products created in the frequency conversion process(es).