A novel open loop structure for phase shifting and frequency synthesizing
This paper presents a new open-loop phase shifter and frequency synthesizer which can be implemented by small hardware. In the proposed method the differential square wave is converted to a differential ramp. Then the cross points of two ramps are detected as the middle points of high or low durations and are recovered to full digital levels, for 90 degrees shifting operation. 4-phases in 50 MHz frequency can be generated by 3.5 mW power consumption and 60 mu m x 60 mu m area. All circuits have been simulated in 0.35 mu m CMOS technology.
frequency synthesizer phase shifter frequency multiplier dll pll