Title :
A 450 Mb/s analog front-end for PRML read channels
Author :
Bloodworth, B. ; Siniscalchi, P. ; De Velmann, G. ; Jezdic, A. ; Pierson, R. ; Sundararaman, R.
Author_Institution :
Texas Instrum. Inc., Dallas, TX, USA
Abstract :
The high user densities and data rates supported by today´s hard-disk drives (HDD) demand complex read channel ICs. High-performance analog front-end (AFE) circuits provide automatic gain control (AGC), programmable band limiting and pulse shaping prior to signal sampling and further processing of the data in the digital domain. A 450 Mb/s analog front-end, integrated into a 16/17 code rate EPR4 read channel, contains an AGC loop, which includes a programmable gain stage (PGA), an exponential variable-gain amplifier (VGA), a 7/sup th/-order 120 MHz lowpass filter (LPF), an active dc offset cancellation circuit, and digital feedback. Utilizing multilevel qualification and a variable loop time constant, the AGC acquires a 12 dB gain change within 5 data bytes. Thermal asperity (TA) and amplitude asymmetry compensation make the analog front-end ideally suited for magnetoresistive (MR) head-based applications. Implemented in 5V/3.3V dual voltage 0.35 /spl mu/ BiCMOS, the complete circuit occupies 2.29 mm/sup 3/ and dissipates 232 mW.
Keywords :
BiCMOS analogue integrated circuits; automatic gain control; circuit feedback; disc drives; hard discs; magnetic heads; magnetoresistive devices; maximum likelihood detection; partial response channels; signal sampling; 0.35 micron; 16/17 code rate EPR4 read channel; 232 mW; 3.3 V; 450 Mbit/s; 5 V; BiCMOS; PRML read channels; active dc offset cancellation circuit; amplitude asymmetry compensation; analog front-end; automatic gain control; data rates; digital feedback; exponential variable-gain amplifier; hard-disk drives; lowpass filter; magnetoresistive head-based applications; multilevel qualification; programmable band limiting; programmable gain stage; pulse shaping; read channel ICs; signal sampling; thermal asperity; user densities; variable loop time constant; Active filters; Circuits; Digital filters; Electronics packaging; Gain control; Hard disks; Limiting; Pulse amplifiers; Pulse shaping methods; Signal sampling;
Conference_Titel :
Solid-State Circuits Conference, 1999. Digest of Technical Papers. ISSCC. 1999 IEEE International
Conference_Location :
San Francisco, CA
Print_ISBN :
0-7803-5126-6
DOI :
10.1109/ISSCC.1999.759075
