Patent ID: 7873333
Filing Date: 2011-01-18
Classification: H03G

Abstract:
1. A transmitter circuit including a phase locked loop that controls a phase of a power output of a power amplifier and an amplitude loop that controls an amplitude of the power output of the power amplifier, comprising: a switching control unit that switches the amplitude loop from an open loop to a closed loop or vice versa, wherein, in case that the power amplifier delivers a large power output, the switching control unit brings the amplitude loop to the closed loop, wherein, in case that the power amplifier delivers a small power output, the switching control unit brings the amplitude loop to the open loop, wherein the phase locked loop includes: the power amplifier; a first loop filter; a limiter amplifier; and a phase detector, wherein the amplitude loop includes: the power amplifier; an amplitude-modulated wave detection circuit; an amplitude comparator; and a second loop filter, wherein, in case that the power amplifier delivers a large power output, the amplitude loop is brought to a closed loop so that the power output will have the amplitude thereof modified based on an output signal of a modulator and a feedback control signal, and wherein, in case that the power amplifier delivers a small power output, the amplitude loop is brought to an open loop, in which the amplitude loop does not include the amplitude-modulated wave detection circuit, amplitude comparator, and second loop filter, so that the power output will have the amplitude thereof modified based on the output signal of the modulator.