Phase noise of the Backward-wave oscillator based on a 3rd order PLL

The processing of analysis, design and phase noise measurement of the Backward-wave oscillator (BWO) based on a 3rd order PLL is presented in this paper. The design utilizes a Charge-pump Phase-locked loop IC and a harmonic mixer in conjunction with a spectrum analyzer locking the BWO to a Tek 2782 spectrum analyzer. We adopt a GPIB cable connecting the spectrum analyzer to a computer and created a virtual instrument by Labview program on the screen. The SSB phase-noise of this Phase locked BWO was measured and the typical value in the frequency range 135 GHz to 160 GHz is better than 63 dBc/Hz at offset frequencie 1 kHz.