Tuning of the Relative Phases of a Rotary Travelling Wave Oscillator

This work describes the implementation of a simple phase detector and an algorithm to adjust variable Transmission Line (TL) capacitance to tune the phases of an RTWO. Symmetrical XOR (SXOR) phase detectors were designed, fabricated in SiGe BiCMOS and tested to resolve one degree of phase error over 35 to 55 degrees and 80 to 100 degrees up to 12 GHz. These phase detectors were used to measure and calibrate the phase of nominal 45 degree transmission line sections of an 18-GHz RTWO fabricated in SiGe BiCMOS . This phase tuning was carried out by a phase alignment algorithm that can be implemented easily in Verilog. This RTWO phase tuning system was shown to function correctly in simulation. Although the fabricated version did not converge correctly, the algorithm was able to adjust the phase of RTWO TL sections. The circuit problem preventing convergence is understood and can be corrected.