R. Harjani, A LOW-POWER CMOS VGA FOR 50 MB S DISK-DRIVE READ CHANNELS/, IEEE transactions on circuits and systems. 2, Analog and digital signal processing, 42(6), 1995, pp. 370-376
We describe an all CMOS variable gain amplifier (VGA) suitable for use
in disk drive read channels. The VGA maintains a 3 dB bandwidth great
er than 85 MHz throughout its gain range, This ensures good phase line
arity for data transfer rates of up to 50 Mb/s, The VGA provides a 25
dB gain variation along an ideal exponential gain to control voltage c
urve and 30 dB of gain control if ideal exponential characteristics is
not absolutely necessary. The VGA achieves the necessary exponential
gain to control voltage characteristics intrinsically using only MOS t
ransistors as a single unit to reduce power and area consumption. over
all power consumption is less than 10 mW for the VGA circuit excluding
the off-chip buffer circuits.