Design of Low-Noise X-band Frequency Source Based on DDS-PLL

This paper proposes a DDS directly excites PLL frequency source, which is small, portable, stable, low-phase noise and fast frequency hopping. In the design, the loop bandwidth, phase margin, and phase detection frequency are set rationally through theoretical calculations, while coplanar waveguide, horseshoe-shaped etching, and continuous impedance are used to improve system performance. The frequency range of PLL is from 8.5GHz to 9.5GHz. The phase noise is -115dBc at 100KHz frequency offset, the phase locked time is 580ns when the PLL operating at 9.0GHz.