A CMOS UHF Harmonic Rejection Transceiver With 2-D LO Phase Calibration for TV White Space Applications

A CMOS ultra-high frequency-band RF transceiver based on 8-phase harmonic rejection mixer (HRM) architecture with an integrated fractional-N PLL synthesizer is presented for television white space applications. A divide-by-2 and a phase interpolator (PI) circuit are used to generate the 8-phase LO signals for the HRM. The synthesizer output frequency is two times higher than the desired band frequency. The PI is tunable to allow 7-bit calibration of 45° and 135° LO phases. A systematic 2-D calibration scheme that is applicable to both the receiver and transmitter is described. It is demonstrated that only 45° and 135° LO phase calibration is sufficient to minimize the third and fifth harmonic components. Implemented in 0.18- $\mu$ m CMOS, the RF transceiver covers 470–806 MHz, achieving the third and fifth harmonic suppressions below −48 and −56 dBc at the receiver, and the harmonic emission below −51 dBc at the transmitter.