宽带低杂散LFM信号的产生方法与系统设计

Generating Method and System Design of Wide-band Low Spurious LFM Signal

针对宽带雷达线性调频信号产生,采用FPGA电路和宽带DAC电路直接产生50 MHz^550 MHz的线性调频中频信号。将中频信号上变频到2 GHz^2.5 GHz的射频频段,再经过2倍频获得4 GHz^5 GHz的宽频带线性调频信号。为进一步提高射频输出信号的幅度/相位特性,采用幅/相预失真校准方法,并精心设计信号产生系统的中频电路和射频电路,进行了实验研究与分析。对实际系统的测试结果表明,系统产生LFM信号的带外杂散优于-55 dB,带内起伏小于±2 dB,且系统稳定、可靠。

For generating wideband radar linear frequency modtdation （LFM） signal, the FPGA circuit and wideband DAC circuit are used to generate 50 MHz -550 MHz LFM IF signal. The IF signal is up-converted to 2 GHz -2.5 GHz RF bands, and then after double octave obtains 4 GHz - 5 GHz wideband LFM signal. To further improve the RF output signal amplitude/phase characteristics, the amplitude/phase pre-distortion calibration methods are used, the IF and RF circuits are carefully designed, experiments and analysis are cartied out. According to the measurement results, the spurious signal involved in the system output is lower than -55 dB, the ripple in the band is below ＋2 dB. This system is quite stable and its performance meets the requirement of actual application.