This paper presents a broadband power amplifier (PA) for K/Ka-band applications. The PA is designed using a 0.7 μm InP DHBT process and employs a pre-matched cascode structure to enhance the breakdown voltage capability. By leveraging the even-order harmonic cancellation effect of a differential cascode topology combined with high-coupling on-chip transformer baluns, ultra-wideband impedance matching is achieved. The chip operates from 18 to 40 GHz with a compact size of 1.2 mm × 2.2 mm. Measurement results demonstrate a saturated output power of 21 dBm and a power-added efficiency (PAE) ranging from 26.5% to 37.8%. This design provides an effective solution for broadband PAs in K/Ka-band applications.
Cheng et al. (Thu,) studied this question.