A highly efficient and linear wideband digital polar CMOS class-E power amplifier (DPA) is presented. Using a compensated wideband Marchand balun with re-entrant coupled lines for the output matching network, more than 50% peak drain efficiency over 2.2-3GHz with 16-17dBm Pout are achieved. The linearity is significantly improved by nonlinearly sizing the DPA array along with overdrive-voltage control and concurrent multiphase RF clocking. The chip prototype is fabricated in 40nm bulk CMOS and the balun is fabricated on a two-layer PCB. Measured results show -40dBc for a 40MHz QAM signal at 2.6GHz without using any sort of DPD. The measured peak Pout, DE and PAE at 2.6GHz are 17.2dBm, 67% and 45% with VDD=0.7V.@en

This paper presents a wideband linear direct digital RF modulator (DDRM) in 40nm CMOS technology. It features an advanced 2nd-order-hold interpolation filter and I/Q-interleaving harmonic rejection RF DACs. The 2×9-bit DDRM core occupies 0.21mm2 and consumes only 110mW at 1 GHz. Within the 0.9-3.1GHz frequency range, the peak output power reaches +9.2dBm and the 3rd/5th harmonic rejection, C-IMD3, and OIP3 are respectively better than 30 dB, -44 dBc, and +25 dBm. The EVM and ACPR at 3 GHz for a 57-MHz 64-QAM signal are better than -30 dB and -45 dB, respectively, and ACPR remains as low as -44 dBc up to a wide bandwidth of 110 MHz.@en

This paper presents an intrinsically linear wideband polar digital power amplifier (DPA) operating in semi class-E/F2 mode. Without using any type of digital pre-distortion (DPD), the proposed architecture achieves high linearity by accurately controlling its AM-AM and AM-PM characteristic curves through nonlinear sizing, overdrive-voltage control, and multiphase RF clocking without compromising the achievable output power or efficiency. Measurement results of the fabricated prototype in 40-nm bulk CMOS show -46 and -40 dBc adjacent channel power ratio (ACPR) for 20and 40-MHz orthogonal frequency-division multiplexing (OFDM) signals, respectively. The measured error vector magnitudes (EVM) are -36 dB and -33 dB, respectively. Measured results indicate a PSAT, peak drain efficiency (DE), and power-added efficiency (PAE) of 14.6 dBm, 44%, and 26%, respectively, using a 0.5-V supply for the output stage at 2.2 GHz.@en