A fully integrated dual-frequency VCO providing not only a high frequency LO signal to transceiver mixers but also a half-LO-frequency signal to a PLL is described. The circuit has 1.2 GHz tuning range at 7 GHz, 25-dB suppression of fundamental-frequency (3.5-GHz) signal at 7-GHz port, and more than 20dB suppression of 7-GHz-signal at 3.5-GHz port. The VCO chip was packaged and resembled on board for phase-noise measurement. A phase noise of – 80 dBc/Hz at 100kHz offset frequency was obtained. This work avoids the use of frequency dividers, hence the chip sizes, power consumption and cost are reduced.
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