A Ka-Band High Power and Low Phase Noise GaN MMIC Oscillator with a Compact Open-Loop Folded Resonator Filter

This paper presents a Ka-band high power and low phase noise GaN oscillator with a 2
^nd
-order folded open loop filter employed in the feedback loop. The concept of complex quality factor
$(\boldsymbol{Q}_{\mathbf{sc}})$
is employed to precisely determine the oscillation frequency. The parasitics of the GaN transistor are extracted, revealing a
$\boldsymbol{Q}_{\mathbf{sc}}$
peak of 236 at 30.6 GHz for the overall passive network. Experimental results demonstrate an oscillation frequency of 30.5 GHz, closely matching the simulated results. Phase noise (PN) measurements yield -113.3 dBc/Hz and -136.8 dBc/Hz at 1 MHz and 10 MHz-offset frequency, respectively. The peak output power is 10.4 dBm with a figure-of-merit (FoM) up to -184.7 dBc/Hz, demonstrating performance among the best compared to published GaN MMIC oscillators in a similar frequency range. The core chip area is only
$\boldsymbol{1.62} \times \boldsymbol{0.73}\ \mathbf{mm}^{\boldsymbol{2}}$
.