13.07.2015 Views

MPhil thesis of Lo Chi Wa - Department of Electronic & Computer ...

MPhil thesis of Lo Chi Wa - Department of Electronic & Computer ...

MPhil thesis of Lo Chi Wa - Department of Electronic & Computer ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

finPhaseDetectorLPFVCOfo1/NDACDACChannel selectionVCOfinPhaseDetectorLPF-Rfo1/NChannel selectionFig. 15 The evolution <strong>of</strong> fast-switching PLL frequency synthesizer – a) two possible configurationsemploying DAC to increase frequency switching speed; b) employing switchable-capacitor-array toincrease frequency switching speedAdvantagesIn the proposed approach, the capacitance <strong>of</strong> the varactor controlled by the loop and thecapacitance <strong>of</strong> the switchable-capacitor array are added. The capacitance <strong>of</strong> theswitchable-capacitor array is controlled directly and linearly without through a varactorwhich has a non-linear voltage-to-capacitance characteristic. As a result, the outputfrequency can be controlled quite linearly and fine tuning from the switchable-capacitor22

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!