A digital baseband processor is provided which receives a system clock generated by a system oscillator and generates a plurality of clock signals from the system clock. The digital baseband processor includes a digital signal processor for executing digital signal processor instructions, a microcontroller for executing microcontroller instructions, and other modules which may require one of the plurality of clock signals for operation. The digital baseband processor also includes a power management circuit which may power down the system oscillator when modules such as the digital signal processor and microcontroller do not require clock signals derived from the system oscillator. The power management circuit may gate off clock signals to modules when those modules do not require clock signals, without powering down the system oscillator.