A resonant tunneling diode (RTD)-based oscillator operating at an output operation frequency of 1.52 THz is proposed. The proposed oscillator utilizes a unique negative differential conductance characteristic and a triple-push principle for high frequency operation. The RTD triple-push oscillator with an on-chip patch antenna has been successfully fabricated by using an InP-based RTD monolithic microwave integrated circuit (MMIC) technology. The fabricated RTD oscillator shows the output power of 1.9 mu W at an output frequency of 1.52 THz. The obtained DC power consumption is 11.6 mW.