High-Speed DDS-Based Generator of Pulses with an Arbitrary Frequency Modulation

We present design and performance verification of a high-speed programmable pulse generator based on an integrated direct digital synthesizer (DDS). The generator can produce pulses with an arbitrary frequency modulation, instantaneous frequency up to 140 MHz, and widths ranging from microseconds to milliseconds. The pulses can be formed into arbitrary sequences with the minimum spacing of 150 ns. We experimentally verify performance of the generator for pulses with the linear frequency modulation (LFM), obtaining an excellent performance in terms of the compression ratio and side-lobes level. We also demonstrate the ability of our generator to produce pulses with a nonlinear frequency modulation (NLFM). Experimental analysis of an exemplary NLFM pulse produced by the generator confirms that NLFM allows to reduce the side-lobes level without deteriorating the compression ratio.