Davy H. Choi

Design considerations and implementation of a programmable high-frequency continuous-time filter and variable-gain amplifier in submicrometer CMOS

We report on an approach to designing high-speed, low-voltage programmable continuous-time filters with an embedded variable-gain amplifier (VGA). The methods we describe here are aimed at implementation in ultra-short-channel, low-voltage CMOS technologies. The seventh-order equiripple filter and VGA combination described here has a -3-dB frequency programmable from 30 to 100 MHz, gain programmable from 0 to 17 dB and 12 dB of boost.

An analog front-end signal processor for a 64 Mb/s PRML hard-disk drive channel

Synchronous channel designs, such as partial response maximum likelihood (PRML), are viable for high areal density on a hard-disk drive (HDD). Previously-published PRML channels include a 56 Mb/s channel design but without an on-chip programmable filter, synthesizer or servo demodulator. This 5V BiCMOS integrated circuit contains all the analog front-end functions necessary for a 64Mb/s HDD channel using a rate-8/9 code.<<ETX>>

An analog front-end signal processor for a 64 Mbits/s PRML hard-disk drive channel

This BiCMOS IC contains all the analog front-end components necessary for the design of a 21-64 Mb/s HDD channel. Major functional blocks include an automatic gain control circuit having both analog and digital modes of operation, a programmable filter with 6-33 MHz bandwidth range, two phase-locked loops with 24-72 MHz center frequency ranges, a differential 6 bit flash A/D converter with 24-72 MHz sampling rates, and a write precompensator having 600 ps step size. >

S/N Optimized, Programmable 1–10 MHz Bandwidth and 0–20 dB Gain, Precision I-Q Communication Channel for Digital Video Applications

An analog part of a digital-video quadrature demodulation scheme is built using a 7 GHz, 0.8 μm biCMOS process. The scheme provides for 1–10 MHz cutoff frequency and 0–20 dB gain controls and dissipates 250 mW from a power supply of 5 V. The channel filtering is realized by two identical 4th Order Butterworth lowpass filters built with the gm-C technique. They are equipped with cutoff programming and in-package trim tuning for cutoff adjustment. A programmable gain amplifier is placed in front of each filter for better joint noise and intermodulation performance. Such an arrangement allows to operate the filter at a maximum signal level improving the worst-case channel S/N by 6.5 dB. For the in-band components the worst case S/N is better than 41 dB, whereas THD and IMD are less than −48 dB. This single-ended channel achieves PSRR of 42 dB.