A Direct Digital Frequency Synthesizer with CMOS OTP ROM§

A direct digital frequency synthesizer (DDFS) using on-chip CMOS one-time programmable read-only memory (OTP ROM) are presented. A straight-line approximation algorithm for sinusoid with compensation is adopted such that the accuracy could be maintained and the cost is reduced. Most important of all, a CMOS OTP ROM is employed as a look-up ROM table to simplify the ROM fabrication without any additional process steps. The proposed DDFS design is implemented using a typical 1P6M 0.18 mum CMOS process. It has a 12-bit amplitude resolution with 86.89 dB spurious free dynamic range (SFDR) using a small ROM size of 256 bits.