Title :
An automatic phase adjustment scheme for RF and Cartesian feedback linearizers
Author :
Faulkner, Michael
Author_Institution :
Sch. of Commun. & Inf., Victoria Univ. of Technol., Melbourne, Vic., Australia
fDate :
5/1/2000 12:00:00 AM
Abstract :
Amplifier linearization schemes based on modulation feedback (e.g., Cartesian feedback) require a phase correction circuit to stop instability and limit the level of the out-of-band noise floor. It is shown that the optimum phase corrector setting corresponds to the minimum output power condition of the amplifier. 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 output power and minimizes this by using a simple direct search algorithm. Phase correction to within 5° of optimum can be obtained after about 50 iterations. The performance is limited by hysteresis in the supply current feedback signal
Keywords :
circuit stability; electric current measurement; feedback amplifiers; linearisation techniques; noise; nonlinear network analysis; phase measurement; power amplifiers; radiofrequency amplifiers; search problems; Cartesian feedback linearizer; RF feedback linearizer; RF feedback system; RF nonlinear power amplifier; amplifier linearization; automatic phase adjustment; current measurement; direct search algorithm; instability; minimum output power condition; modulation feedback; optimum phase corrector setting; out-of-band noise floor; output power measure; performance; phase correction circuit; phase error measurement; supply current; supply current feedback signal hysteresis; system noise model; Circuit noise; Current supplies; Feedback circuits; Noise level; Phase modulation; Phase noise; Power amplifiers; Power generation; Radio frequency; Radiofrequency amplifiers;
Journal_Title :
Vehicular Technology, IEEE Transactions on
