Performance of automatic phase adjustment using supply current minimisation in a RF feedback lineariser

摘要

Amplifier linearisation schemes based on feedback (e.g. cartesian feedback) require a phase correction circuit to stop instability and limit the level of the out-of-band noise floor. A new and very simple method by which the phase correction circuit is adjusted is described. The scheme uses the supply current to the final stage amplifier as a measure of the out-of-band noise, and minimizes this by using a simple direct search algorithm. Phase correction to within 5 degrees of optimum can be obtained after about 50 iterations.