A 500 msample/s 6-bit Nyquist rate ADC for disk drive read channel applications

The analog-to-digital conversion required in most disk drive read channel applications is designed for good dynamic and noise performance over a wide input frequency range. This paper presents a 500MSam- ple/s 6-Bit ADC and its embedded implementation inside a disk drive read channel, using a 0.35µm CMOS single-poly, triple-metal process. The converter achieves better than 5 effective number of bits (ENOB) for input frequencies up to Nyquist frequency (f
in
= 1/2f
s
) and sampling frequencies f
s
up to 400MHz. It also achieves better that 5.6 ENOB for input frequencies up to 1/4f
s
over process, temperature and power supply variations. At maximum speed (f
s
= 500MHz) the converter still achieves better than 5 ENOB for input frequencies up to f
in
= 200MHz. Low frequency performance is characterized by DNL < 0.38LSB and INL < 0.2LSB. The converter consumes 225mW from a 3.3V supply when running at 300MHz and occupies 0.8mm
²
of chip area.