A Frequency-Agile RF Frontend Architecture for Multi-Band TDD Applications

Abstract

Emerging wireless standards specify dozens of bands spanning several octaves, which need to be supported in form-factor and energy constra ined mobile devices targeting ubiquitous connectivity. However, in current multi-band radio implementations, signi ficant redundancy is still the norm in the RF frontend. This work introduces an improved architecture for multi-band, time-division duplexed (TDD) radios, which replaces multiple narrowband frontend co mponents with a frequency-agile solution, tunable over a wide frequency range. A highly digital architecture is adopted, leadin g to a fully integrated solution wherein both ef ficiency and achievable frequency range bene fit from CMOS scaling. A prototype is integrated in 45 nm SOI CMOS. Peak PA output power is 27.7 0.5 dBm from 1.3 to 3.3 GHz, with up to 30% total ef ficiency at 2 V. For TDD LTE applications, better than 30 dBc ACLR and 30 dB EVM is measured with 64 QAM, 20 MHz signals from 1.44 to 3.41 GHz, with up to 17.2% average ef ficiency and 23.4 dBm average power. The LNA achieves 14 dB, NF = 4.4 1.6 dB and IIP 7d B mf r o m1 . 3t o3 . 3G H zw h i l ed r a w i n gj u s t6m A from 1 V. The demonstrated freq uency range covers a total of 11 TDD bands.