A 2.4 GHz Power Amplifier With 40% Global Efficiency at ${-}$ 5 dBm Output for Autonomous Wireless Sensor Nodes

Energy scavenged Wireless Sensor Nodes (WSNs) usually require a small output power ( 0 dBm) due to their short-range application and limited power budget. This makes the RF Power Amplifier (PA) design differ from conventional PAs as the output power becomes comparable to the PA driver's power consumption. In this letter, a 2.4 GHz tuned switching PA and driver is proposed with an on-chip duty cycle calibration loop to enhance efficiency. A prototype is fabricated in 40 nm CMOS technology and supports On-Off keying (OOK). Measurements show a global efficiency of 40% when delivering -5 dBm to a 50 Ω load.