A Fully Integrated Dual-Frequency Push-Push VCO for 5.2/5.8-GHz Wireless Applications

A fully integrated dual-frequency VCO for 5.2/5.8-GHz wireless LAN 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 better than-80 dBc/Hz at 100kHz offset frequency was obtained. This work obviates the use of frequency dividers, hence the chip sizes, power consumption and cost are reduced.