A novel and useful apparatus for and method of local oscillator generation employing an exception handling mechanism that permits an oscillator having a limited modulation range to handle the large modulation ranges demanded by modern wideband wireless standards such as 3G WCDMA, etc. A controllable oscillator generates an RF signal having four quadrature phases in accordance with an input command signal. An exception handler compares the frequency command information against a threshold. If it exceeds the threshold a phase jump and a residue frequency command are generated. The residue frequency command is input to an oscillator which is operative to generate an RF signal having four quadrature phases. The phase jump is input to a quadrature switch which functions to select one of the four quadrature phase signals as the output RF signal which is then fed to a digital power amplifier.