A 500-MSample/s, 6-bit Nyquist-rate ADC for disk-drive read-channelapplications

摘要

The analog-to-digital conversion required in most disk-drivenread-channel applications is designed for good dynamic and noisenperformance over a wide-input frequency range. This paper presents an500-MSample/s, 6-bit analog to-digital converter (ADC) and its embeddednimplementation inside a disk-drive read channel, using a 0.35-Μm CMOSndouble-poly (only one poly layer was used in the ADC), triple-metalnprocess. The converter achieves better than 5 effective number of bitsn(ENOB) for input frequencies up to Nyquist frequency (fin=fns/2) and sampling frequencies fs up to 400 MHz. Itnalso achieves better that 5.6 ENOB for input frequencies up to fsn/4 over process, temperature, and power-supply variations. Atnmaximum speed (fs=500 MHz), the converter still achievesnbetter than 5 ENOB for input frequencies up to fin=200 MHz.nLow-frequency performance is characterized by DNL<0.32 LSB andnINL<0.2 LSB. The converter consumes 225 mW from a 3.3-V supply whennrunning at 300 MHz and occupies 0.8 mm2 of chip area