A PLL based 12GHz LO generator with digital phase control in 90nm CMOS

A 12 GHz PLL with digital output phase control has been implemented in a 90 nm CMOS process. It is intended for LO signal generation in integrated phased array transceivers. Locally placed PLLs eliminate the need of long high frequency LO routing to each transceiver in a phased array circuit. Routing losses are thereby reduced and design of integrated phased array transceivers become more modular. A chip was manufactured, featuring two separate fully integrated PLLs operating at 12 GHz, with a common 1.5 GHz reference. The chip, including pads, measures 1050 × 700 ¿m². Each PLL consumes 15 mA from a 1.2 V supply, with a typical measured phase noise of -110 dBc/Hz at 1 MHz offset. The phase control range exceeds 360°.