Low phase noise reference oscillator with integrated PMOS varactors for digital satellite receivers

For the first time, a low phase noise reference oscillator with integrated PMOS varactors is realized. Other integrated varactor options are qualitatively analyzed, and will be shown to fall short for application in a reference oscillator. Carrier to noise levels of 87 dBc/Hz @ 10 kHz offset and better are measured over a tuning range of 225 MHz to 310 MHz. Power supply voltage is 3.5 V and measured dissipation 14 mW. The design is optimized for use in zero-IF digital satellite front-ends which have a double loop tuning system. In double loop architectures a relatively noisy on-chip I/Q RC oscillator is wideband locked to a clean reference oscillator to achieve phase noise levels sufficiently low for QPSK reception. A low cost implementation of the reference oscillator is realized, since only the coils of the reference oscillator are off-chip