PHASE NOISE OF A RESONANT-TUNNELING RELAXATION-OSCILLATOR

Experimental results are presented for the phase noise of a relaxation oscillator consisting of a resonant-tunneling diode in series connect ion with a transmission line, one end of which is shorted. Unlike cons tant-wave negative-resistance oscillators, the resonant-tunneling rela xation oscillator (RTRO) emits a sequence of sharp current pulses that are mode locked to the fundamental mode of the cavity formed by the s hort-circuited transmission line. The phase noise in the RTRO was inve stigated with and without injection locking by a weak sinusoidal sourc e. Injection-locking gain of 51 dB was measured for fundamental inject ion locking. Subharmonic injection locking was demonstrated out to the 12th subharmonic. Also, timing jitter as low as 200 fs was measured f or an RTRO that emitted similar to 30 ps pulses at a repetition rate o f 1.1 GHz. (C) 1998 American Institute of Physics. [S0003-6951(98)0012 0-X].