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The design of a high-speed analog-to-digital (A/D) converter for hard disk drive read channels is described. The A/D converter uses a flash architecture with an interleaved sample and hold and interpolating comparator pre-amplifiers. It has 6 bits of resolution at full speed as well as a 7 bit mode operating at a lower speed. The 7 bit mode is useful for servo signal processing. This A/D converter has been implemented in a four-level metal single-poly 0.25 /spl mu/m CMOS technology. The device operates at a speed of up to 700 MSamples/s in the 6 bit mode while maintaining a signal-to-noise-plus-distortion rate (SNDR) of greater than 35 dB at input frequencies of up to one-fourth the sampling rate. In the 7 bit mode, the device operates at up to 200 MSamples/s with a SNDR greater than 41 dB. It occupies an active area of 0.45 mm/sup 2/ and consumes less than 187 mW of power.
Date of Publication: Dec. 2000