Feedforward Amplifier using Equal Group-Delay Signal Canceller

In this paper, a new signal canceller that can matches an out-of-phase and a group delay of two path signals simultaneously is proposed. The simultaneous matching of the out-of-phase and the group delay time between two paths can makes a broadband signal cancellation possible. A feedforward linearizing power amplifier that adopts the proposed signal cancellers is fabricated on IMT-2000 base-station transmitting band. The main signal cancellation (or the 1^st) loop of the fabricated feedforward amplifier cancel input signal more than 26.3dB and the intermodulation distortion (IMD) signal cancellation (or the 2^nd) loop cancel IMD signal more than 15.2dB for 200MHz bandwidth. With the two-tone signals amplification process, the C/I ratio of the amplifier is improved 20.8dB, where the two tones are 2115MHz and 2165MHz, respectively