A LOW-POWER CMOS VGA FOR 50 MB S DISK-DRIVE READ CHANNELS/

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.