The performance of monolithic integrated oscillators using submicron InAlAs/InGaAs HEMTs (high electron mobility transistors) at 35 GHz is presented. Two different types of feedback schemes were employed showing distinct bias tuning features. A large-signal analysis was performed to analyze their power characteristics. The dual feedback oscillator had an output power of 8.2 mW and showed a high DC-to-RF efficiency of 36% at 35.6 GHz.