Abstract: A phase-controlled oscillator using a resonant tunneling diode (RTD), which is included in a self-oscillating biasing circuit. A biasing voltage controls the phase of the pulsating output relative to a pulsating input signal. If the output modulates a laser, the pulse position of the laser output can be varied in time. If the output modulates a microwave or other emitter have an electromagnetic frequency equal to that of the RTD biasing circuit, the electromagnetic phase of the emission is controlled, thereby allowing phase-array radars using multiple RTD biasing circuits. Also, multiple RTD biasing circuits can have self-oscillation frequencies which are rational fractions of a single master clock frequency driving all of them. The outputs then have different frequencies but are phase locked.