Design of programmable embedded IF source for design self-test

A programmable embedded IF source has been designed for embedded communication self-test using an on-chip memory block, a shifter register, and a noise-shaping filter. An on-chip memory element is programmed with software-generated delta-sigma modulated code. The frequency of the IF source is programmable by using a variable on-chip clock generator. The design simulation shows 45 dB single-tone SFDR with a 1200 /spl mu/m /spl times/ 900 /spl mu/m chip area. Another improved design is in progress, which is implemented with analog FIR filtering techniques. This approach relaxes the design specifications for noise shaping filters, yielding a smaller circuit.