A quadrature LO-generator using an external single-ended clock receiver for dual-band WLAN applications

Abstract

A low phase noise quadrature LO-generator for dual-band wireless local area network (WLAN) applications is presented. The quadrature LO-generator is composed of a clock receiver, a CML divider, and two quadrature dividers for the dual-band, respectively. A clock receiver converts the single-ended clock to a differential signal. Then a quadrature divider with a 25% duty cycle generates four quadrature signals for mixers. The split-grounded architecture and multiply ground pads decrease the inductive component of ground impedance as well as the ground bounce of the single-ended input. The phase noise is −143dBc/Hz and −149dBc/Hz at 1MHz offset in the 2.4-GHz and 5-GHz bands, respectively.

A Low Spur and Low Jitter Quadrature LO-Generator Using CML Inductive Peaking Technique for WLAN Transceiver

“…Followed by an off-chip Balun, a single-ended clock source at the frequency of 4.8 GHz is transformed to differential signals. The differential input mode and a lower input frequency of external VCO can alleviate the issue of ground bounce due to the inductor and capacitor of the bonding wire and suppress the common-mode noise [29]. However, the off-chip balun would cause a large in-phase/quadrature-phase (I/Q) imbalance of the clock signal, and the I/Q phase imbalance would appear on the quadrature LO signals at the output node.…”