neoflash
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Mixed-Signal Designer
Posts: 397
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Hi, folks:
I've got a question on DCO's sigma-delta modulation. The modulator itself is out of the question. However, since the DAC is accomplished inside DCO through discrete small capacitors' on/off, the high intrinsic non-linearity there will destroy the spectrum.
It is impossible to make those capacitor tuning gain linear in my opinion.
I do not know how people solve that problem. Please suggest, thanks.
Reference: JSSCC’2005 Nov. Robert Bogdan "a digitally controlled oscillator in a 90nm digital cmos process for mobile phones"
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