An 802.15.4/4z-compliant UWB All-digital Transmitter with Hybrid FIR Filtering Achieving 47dBr Sidelobe Suppression

This paper presents an IEEE 802.15.4/4z-compliant UWB all-digital transmitter that incorporates hybrid FIR filtering. The reconfigurable and compact hybrid filter consists of a polyphase digital FIR filter and a transformer-combined FIR filter. With the proposed filter, the transmitter achieves 47 dBr sidelobe suppression without any off-chip filters, fully complying with worldwide power spectral density regulations. An on-chip parallel-combining transformer is implemented, which realizes FIR summation while also accomplishing load modulation, thereby enhancing power back-off (PBO) efficiency. Fabricated in 28nm CMOS technology, the transmitter achieves 14.6 dBm peak output power with power added efficiencies (PAEs) of 29% and 25% for 0-dB/6-dB PBOs at 6.5 GHz.