A 2.5GHz 32nm 0.35mm 2 3.5dB NF −5dBm P 1dB fully differential CMOS push-pull LNA with integrated 34dBm T/R switch and ESD protection

Process scaling enables SoC integration of radio and large digital systems at reduced cost and area. Furthermore, the crowded spectrum requires high linearity receivers to enable co-existence in the 2.4GHz ISM band. Inductorless LNA designs have been studied to make use of the excess f T in advanced CMOS technologies to lower cost [1]. However, an inductively tuned LNA has the advantage of improved out-of-band rejection, and can be readily integrated with a transmit/receive (T/R) switch to provide isolation in the TX mode without the need for additional inductors [2]. In this paper, a 2.5GHz fully differential tuned LNA with integrated T/R switch is designed in a High-K metal gate 32nm digital CMOS process, and packaged in an SoC-compatible flip-chip package. Reliability constraints of the package severely limit the ability to depopulate soldering bumps, and RF components must be designed taking the bump location into account. The LNA achieves a 3.5dB NF, −5dBm P 1dB at 2.5GHz while drawing 11mA from a 1.8V supply. LNA performance is enabled by (1) use of a push-pull topology that exploits the equal strength of p and n transistors to improve linearity, (2) use of nested coupled inductors (NCI) for low-noise input matching and to reduce area. The T/R switch handles 34dBm of power with an insertion loss of 1.1dB at 2.5GHz. T/R switch performance is enabled by (1) reuse of LNA gate inductor to enable low RX mode loss [2], (2) use of remote body-contacted TX switch with high power handling and ESD protection for a transformer-coupled PA.