An L-Band Low Spurious Multi-Tuned Frequency Synthesizer

Abstract

This paper designs an L-Band 1880-1980 MHz low spurious Multi-tuned frequency synthesizer. The frequency source utilizes a DDS to directly stimulate a PLL, which makes a balance between the DDS and the PLL complementary to each other, realizing better specifications. Meanwhile, in order to achieve better spurious suppression with wide loop bandwidth, a method based on triple tuned algorithm is introduced. This algorithm avoids the high level spurious components triggered by the DDS falling in PLL’s bandwidth, refining the structure of the DDS-directly-stimulating PLL circuit frequency lock time and spurious to improve performance. The simulation result shows that the frequency source achieves a frequency range of 1880MHz～1980MHz, a frequency resolution of 1MHz, a spur better than 80dBc, a phase noise of -103dBc/Hz@100kHz and a frequency lock time less than 2 μs.