| 摘要 |
Power reduction in transmitters is very important. One method to realize reduction is to make use of switching power amplifiers (PA) that have a better efficiency. Switching PA concepts are only possible in combination with suitable modulation methods like pulse width modulation (PWM) and out-phasing concepts. However, PWM and out-phasing concepts rely on accurate phase control and duty cycle of the signals. Digitally generation of signals of variable duty cycles and phase is proposed without sacrificing their accuracy. Accordingly, a out-phasing power amplifier arrangement is disclosed, where the generation of the out-phasing angle (&thetas;) and duty cycles (d1 and d2) are controlled by a set of n-bit digital input words (D1, D2, D3, D4). The baseband phase information (&phgr;(t)) is phase modulated back to radio frequency and used as the clock signal of digital circuitry for phase and duty cycle generation after being frequency multiplied by 2n−1. The resolution of the out-phasing angle and of the duty cycle is 2&pgr;/2n and 2&pgr;/2n−1 equivalently. The resolution of the phase information &phgr; is dependent on the PM realization.
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