A Single-Ended Modified Class-E PA With HD2 Rejection for Low-Power RF Applications

This letter presents a fully integrated single-ended power amplifier for ultralow-power applications. The single-ended configuration is possible due to a choke-inductor less output network capable of rejecting the second-harmonic emission. A switching duty-ratio lower than 50% avoids the impedance transformation output network traditionally required for proper class-E operation. At 2.45 GHz, the PA (including the driver) delivers 1.4 dBm to a 50 Ω load and achieves an overall efficiency of 51% while complying with the spurious emission regulation. The prototype was fabricated in 0.13 μm CMOS.