A TV-band white-space transmitter covering a 16x-wide spectrum from 54 to 864 MHz is described. It features a systematic codesign between the architecture and circuits to address the harmonic-mixing problem. Specifically, it incorporates two-stage 6-/14-path harmonic-rejection mixers and low-Q passive-RC/-CLC filters to manage the unwanted harmonic emission fully on chip, achieving an uncalibrated harmonic rejection ratio (HRR) of minimally 59.3 dB (16 samples) for all in-/out-band harmonics. The employed 8-/16-phase LO generator is based on injection-locked 4-/8-phase correctors and even-ratio-only frequency dividers to save the LO-path power (2.5 to 14.2 mW) while lowering the required reference LO frequency (432 to 864 MHz). Without any predistortion, the EVM tested under a 64-QAM OFDM digital-TV signal is 2.9% at 96 MHz, 3.3% at 384 MHz, and 4.0% at 600 MHz. The first (second) adjacent channel leakage ratio is -46 dBc (-43 dBc) at 6 MHz (12 MHz) offset. The power consumption is 53.1 to 75.2 mW and active area is 0.93 mm in 65-nm CMOS.