Title :
A 450-Mb/s analog front end for PRML read channels
Author :
Bloodworth, Bryan E. ; Siniscalchi, Patrick P. ; De Veirman, Geert A. ; Jezdic, Andrija ; Pierson, Richard ; Sundararaman, Raj
Author_Institution :
Storage Products Group, Texas Instrum. Inc., Dallas, TX, USA
fDate :
11/1/1999 12:00:00 AM
Abstract :
A 450-Mbit/s analog front end, integrated into a 16/17 code rate EPR4 read channel for hard disk drives, uses an automatic gain control (AGC) circuit with digital feedback. Multilevel qualification and a variable loop time constant enable the AGC to acquire a 12-dB gain change within 5 data bytes. The front-end circuitry incorporates a programmable gain amplifier (PGA), an exponential variable gain multiplier (VGA), a seventh-order 0.05° equiripple linear phase 20-120-MHz low-pass filter with 0-15-dB high-frequency boost, and active ac coupling. The PGA and VCA combine to give a 48-dB gain range with a 500 MHz -1-dB bandwidth for a power supply of 3 V. The embodiment of thermal asperity and amplitude asymmetry compensation circuitry makes the analog front end ideally suited for applications using magnetoresistive read heads. Implemented in a 5-/3.3-V dual-voltage .35-μm BiCMOS process with a gate-oxide thickness of 75 nm and 16-GHz npn FT, the complete circuit occupies 2.29 mm2 and dissipates 232 mW
Keywords :
BiCMOS analogue integrated circuits; automatic gain control; circuit feedback; disc drives; equiripple filters; hard discs; linear phase filters; low-pass filters; magnetic heads; maximum likelihood detection; partial response channels; 0.35 micron; 16/17 code rate EPR4 read channel; 20 to 120 MHz; 232 mW; 3 V; 450 Mbit/s; 5 V; 500 MHz; 75 nm; BiCMOS process; PRML read channels; active ac coupling; amplitude asymmetry compensation; analog front end; automatic gain control; digital feedback; equiripple linear phase low-pass filter; exponential variable gain multiplier; gate-oxide thickness; hard disk drives; magnetoresistive read heads; multilevel qualification; power supply; programmable gain amplifier; thermal asperity; variable loop time constant; Bandwidth; Coupling circuits; Electronics packaging; Feedback circuits; Gain control; Hard disks; Low pass filters; Nonlinear filters; Power supplies; Qualifications;
Journal_Title :
Solid-State Circuits, IEEE Journal of
