Measurement of Oscillation Frequency and Spectral Linewidth of Sub-Terahertz InP-Based Resonant Tunneling Diode Oscillators Using Ni-InP Schottky Barrier Diode

We report on the measurement of oscillation frequency and spectral linewidth of sub-terahertz GaInAs/AlAs resonant tunneling diode (RTD) oscillators by harmonic heterodyne detection using a Ni-InP Schottky barrier diode integrated with a bow-tie antenna. For an RTD oscillating at 550 GHz and having an output power <= 1 mu W, the measured spectral linewidth was at most 10 MHz; this value is in consistent with that obtained theoretically. A narrow linewidth is expected for a device having high output power and Q-factor. We also accurately measured the frequency change with changing bias voltage for the RTD oscillator; this result is useful for frequency modulation and can be applied to the phase-locked loop system. (C) 2010 The Japan Society of Applied Physics