A 50% PAE K-Band Power MMIC Amplifier

This paper describes the successful development of a 2-stage power amplifier (PA) with 50% efficiency at K-band. A 3-stage variable gain amplifier (VGA) was also developed for a driving stage. Metal - Insulator - Metal (MIM) capacitors and high impedance lines are employed as matching elements to accomplish a compact chip size. As a result, these amplifiers achieve compact chip sizes of 1.0 × 2.0 mm2. In designing the PA, gate widths in the first and second stages are optimized to achieve high efficiency. The PA and VGA have linear gains of more than 18 dB and 24 dB from 18 GHz to 20 GHz, respectively. The PA delivers an output power of 24.6 dBm and a power added efficiency (PAE) of as high as 50% at 19 GHz. To our knowledge, this is the highest PAE at K-band. These results are promising for onboard light weight Active Phased Array Antenna (APAA) at K-band.