On-Chip Integration of Rectangular Loop Slot Antenna Fed Doherty Power Amplifier at Ka-Band

On-chip rectangular loop slot antenna integrated with Doherty power amplifier (RLSA-DPA), in which a singlestage DPA is directly loaded with a single-port antenna, is presented in this paper. By optimizing the loop slot length and introducing slots in the radiating layer, the input impedance matching difficulty is lessened and the operational bandwidth is extended. For validation, the RLSA-DPA was fabricated using a GaN-HEMT process. On-wafer measurement results show that the proposed RLSA-DPA achieves a saturated effective isotropic radiated power (EIRP) of $23.8-24.8 \text{dBm}$, with a calculated saturated EIRP efficiency (Eff ${}_{\text {EIRP }}$) of $\mathbf{5. 3 \% - 7. 1 \%}$ and a smallsignal total gain around -3.8 dB over $30.6-31 \text{GHz}$.