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A modified coupled method for multiphase oscillator is proposed and demonstrated in a standard 0.18-μm CMOS technology. A self-injection-coupled (SIC) technique is used to couple two current-reused differential voltage-controlled oscillators (VCOs). Compared with the conventional parallel-coupled quadrature VCO (QVCO), the proposed QVCO using the SIC technique presents low phase noise without increasing dc power consumption. The proposed SIC-QVCO at 16.28 GHz demonstrated a low phase noise of -125 dBc/Hz at 1-MHz offset frequency and a tuning range of 290 MHz. The dc supply voltage and current consumption are 1.8 V and 6 mA, respectively. The chip size of the proposed SIC-QVCO is 0.75 × 0.6 mm2.
Circuits and Systems II: Express Briefs, IEEE Transactions on (Volume:59 , Issue: 10 )
Date of Publication: Oct. 2012