An Improved Linear Difference Method with High ROM Compression Ratio in Direct Digital Frequency Synthesizer

The increasing demand of low power Direct Digital Frequency Synthesizer (DDFS) leads to the requirement of efficient compression methods to reduce ROM size for storing sine function values. This paper presents a technique to achieve very high compression ratio by using the optimized four-segment linear difference method. The proposed technique results in the ROM compression ratio of about 117.3: 1 and the word size reduction of 6bits for the design of a DDFS with 11-bit sine amplitude output. This high compression ratio result is very promising to meet the requirement of low power consumption and low hardware complexity in digital VLSI technology.