Analog Controlled Adaptive Feedforward Amplifier for IMT-2000 Band

A novel adaptive design for feedforward amplifier linearizer with analog controller is proposed in this paper. Compared previous adaptive linearizing method, this is new design which does not require any pilot signal and intentional signal distortion. In main signal cancellation loop, magnitude and phase of two-path signal in subtracter are compared mutually and controlled for main signal cancellation. In distortion signal cancellation loop, gain and phase of each path is controlled to maintain constant, so that the same level and out-of phase of two-path distortion signal are obtained. A prototype feedforward amplifier with the proposed linearizer has been tested for 3-carrier IS-95 CDMA signals and 20.25dB ACPR is improved.