Dual Loop Push-Push Synthesizer for High Modulation Digital Radios at 38GHz

This paper summarizes the procedure and detail phase noise simulation result for a 38 GHz dual-loop push-push synthesizer, which requires low phase noise, high susceptibility of micro-phonic and phase hit performance over temperature. Push- Push dual loop synthesizer scheme has been used, one narrow band loop is designed for achieving low phase noise with small step size and the second loop is designed for a wide loop bandwidth for high susceptibility of micro-phonic and phase-hit over temperature. This paper shows a step-by-step simulation for a dual loop synthesizer. The simulation includes two push-push VCOs, one narrow band loop for the reference VCO, one wide band loop for the RF VCO, 10 MHz reference, PLL and other RF circuitry. The simulation and prototype testing results match well. The paper also highlights the typical test setups for phase hits and micro-phonics.