A 0.7-8 GHz High IF Frequency-Extended Transmitter Front-End With −47.1-dB EVM at 16 QAM in 65-nm CMOS

This paper presents a 0.7-8 GHz transmitter frontend (TXFE) with high intermedia frequency (IF) input in 65 nm CMOS. To support high image rejection (IR) over a wide carrier frequency bandwidth, a local oscillator (LO), firstly used frequency-extended polyphaser filter (PPF), is proposed. To obtain high linearity performance, a double balanced linearity enhanced multi-gate transistors (MGTR) up conversion mixer is utilized. To achieve an excellent IR over a broad signal bandwidth, a two-stage programmable PPF is employed to ensure a better than 0.2dB/2o quadrature matching from 200 MHz to 550 MHz. The proposed TXFE fabricated in 65 nm CMOS may first achieve 168% relative bandwidth from 0.7-8 GHz for multi-band application. The TXFE achieves an EVM of −47.1 dB, when applying an 140 MHz 16 QAM signal at 2 GHz. It also obtains larger than 2 dBm output power and better than −20 dB image rejection with < 50 ns gain switching and < 200 ns frequency hopping time, which greatly relaxes the bandpass filter requirement before power amplifiers.