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 backoff (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.