The AD8260 includes a high current driver, usable as a
transmitter, and a low noise digitally programmable variable
gain amplifier (DGA), useable as a receiver.
The receiver section consists of a single-ended input preamplifier,
and linear-in-dB, differential-output DGA. The receiver has
a small signal –3 dB bandwidth of 230 MHz; the driver small
signal bandwidth is 195 MHz. The driver delivers ±300 mA,
well suited for driving low impedance loads, even when
connected to a 3.3 V supply.
The AD8260 DGA is ideal for trim applications and has a gain
span of 30 dB, in 3 dB steps. Excellent bandwidth uniformity is
maintained across the entire frequency range. The low output-referred
noise of the DGA is advantageous in driving high
speed ADCs. The differential output facilitates the interface to
modern low voltage high speed ADCs.
Single-supply and dual-supply operation makes the part versatile
and enables gain control of negative-going pulses, such as those
generated by photodiodes or photo-multiplier tubes, as well as
processing band-pass signals on a single supply. For maximum
dynamic range, it is essential that the part be ac-coupled when
operating on a single supply.
The AD8260 preamplifier (PrA) is configured with external
resistors for gains greater than 6 dB and can be inverting or
noninverting. The DGA is characterized with a noninverting
preamplifier gain of 2×. The attenuator has a range of 30 dB and
the output amplifier has a gain of 8× (18.06 dB). The lowest
noninverting gain range is −6 dB to +24 dB and shifts up with
increased preamplifier gain. The gain is controlled via a parallel
port (Pin GNS0 to Pin GNS3) with 10 gain steps of 3 dB per
code. The preamplifier and DGA are disabled for any code that
is not assigned a gain step.
The AD8260 can operate with single or dual supplies from 3.3 V
to ±5 V. An internal buffer normally provides a split supply
reference for single-supply operation; an external reference can
also be used when the VMID buffer is shut down.
The operating temperature range is −40°C to +105°C. The
AD8260 is available in a 5 mm × 5 mm, 32-lead LFCSP.
Applications
- Digital AGC systems
- Tx/Rx signal processing
- Power line transceivers
