Embodiments of the present disclosure provide power-efficient time division duplexing (TDD) mode configurations of frequency division duplexing (FDD) transceivers. Embodiments avoid time slotted operation of the receive and transmit synthesizers, thereby avoiding undesired operation under transient conditions, frequent calibration, and reduced power supply efficiency. In embodiments, a single synthesizer is used to enable TDD operation, thereby reducing power consumption and calibration requirements by approximately 50%. The single synthesizer may be maintained ON at all times, thus allowing the power supply's switching regulator to operate with substantially constant load conditions.