100–1000 MHz Programmable Continuous-Time Filter with Auto-Tuning Schemes and Digital Calibration Sequences for HDD Read Channels

Takahide TERADA  Koji NASU  Taizo YAMAWAKI  Masaru KOKUBO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.6   pp.1050-1058
Publication Date: 2012/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.1050
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
Category: 
Keyword: 
Gm-C filter,  biquad filter,  digitally assisted compensation,  auto tuning,  digital calibration,  analog front end,  

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Summary: 
A 4th-order programmable continuous-time filter (CTF) for hard-disk-drive (HDD) read channels was developed with 65-nm CMOS process technology. The CTF cutoff frequency and boost are programmable by switching units of the operational trans-conductance amplifier (OTA) banks and the capacitor banks. The switches are operated by lifted local-supply voltage to reduce on-resistance of the transistors. The CTF characteristics were robust against process technology variations and supply voltage and temperature ranges due to the introduction of a digitally assisted compensation scheme with analog auto-tuning circuits and digital calibration sequences. The digital calibration sequences, which fit into the operation sequence of the HDD read channel, compensate for the tuning circuits of the process technology variations, and the tuning circuits compensate for the CTF characteristics over the supply voltage and temperature ranges. As a result, the CTF had a programmability of 100–1000-MHz cutoff frequency and 0–12-dB boost.