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, combined in a 5 mm × 5 mm, 32-lead chip scale package.
The receiver section consists of a single-ended input preamplifier, and linear-in-dB, differential-output VGA. Usable at dc and frequencies to 80 MHz; the –3 dB bandwidth is 180 MHz. The driver-amplifier 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 DGA’s low output-referred noise 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 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 user configurable with external resistors for gains greater than 6 dB; as with any high frequency op amp, the gain is inverting or noninverting. The DGA is characterized with a noninverting PrA 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 PrA gain. The gain is controlled via a parallel port (Pin GNS0 to Pin GNS3) with 10 gain steps of 3 dB per code. For any nonused code, the preamplifier and DGA are disabled.
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 32-lead LFCSP.
