Constraint Models of SDRAM-Based Arbitrary Waveform Generator

In the design of synchronous dynamic random access memory (SDRAM)-based arbitrary waveform generators (AWGs), the conflict between the randomness of dynamic memory output data flow and the requirement of seamless signal output is a nonnegligible problem, especially in generators with hopping functions and high sampling rates. By imposing appropriate constraints in the design, the continuity of the output signal and the high throughput utilization can be guaranteed, and the constraints can be modeled to obtain the design boundary requirements under different specifications. In this article, we analyze the throughput model of SDRAM and the access characteristics of an AWG with jump capability. We establish a minimum waveform segment length model and a buffer size model to guarantee continuous signal output, which can obtain sufficient conditions for seamless synthesis of AWGs and be used to support the repeat/jump function of multisegment waveforms. Experimental results on a DDR3 SDRAM-based generator show that the minimum waveform segment length obtained is within 11 words of the measured boundary, and the minimum buffer size is within ten words of the measured boundary, which can effectively improve hardware resource utilization.