Theoretical analysis of subharmonic injection locking in resonant-tunneling-diode terahertz oscillators

Subharmonic injection locking of a resonant-tunneling-diode terahertz oscillator is theoretically analyzed for the purpose of output phase control which can be utilized for beam steering in a phased array. Analytical formulae for the dependences of the locking range and output phase on input and output powers, parameters of the resonator, and bias voltage are obtained. The calculated locking range for the second subharmonic injection reasonably agrees with the reported measurement.