AD8260 Analog Devices Technical Specifications and User Guide

High Current Driver Amplifier and Digital VGA/Preamplifier with 3 d B Steps

AD8260 FEATURES FUNCTIONAL BLOCK DIAGRAM

VOCM INPP INRP INRN INPN TXFB VNEG VNEG

High current driver Differential input—direct drive from DAC

Preset gain: 1.5× −3 d B bandwidth: 195 MHz

VMDO TXOP

Large output drive: >±300 m A

GM ×1

VGA/preamplifier TXEN TXOP

HIGH CURRENT DRIVER

Low noise

VMDI AD8260 VPOS

Voltage noise: 2.4 n V/√Hz

Current noise: 5 p A/√Hz

VNCM VPOS

−3 d B bandwidth: 230 MHz BIAS

Gain range: 30 d B in 3 d B steps VPSB VPSR

−6 d B to +24 d B (for preamplifier gain of 6 d B)

VGA/PREAMPLIFIER

Single-ended preamplifier input and differential VGA ENBL

ATTENUATOR

output

VGAP PRAI

Supplies: 3.3 V to 10 V (with VMID enabled) GM STAGES ±3.3 V to ±5 V (with VMID disabled) VGAN

LOGIC

Power: 93 m W with 3.3 V supplies Power-down for VGA, driver amplifier, and system

VNGR VPSR GNS3 GNS2 GNS1 GNS0 PRAO VNGR

APPLICATIONS

Figure 1. Functional Block Diagram

Digital AGC systems Tx/Rx signal processing Power line transceivers

GENERAL DESCRIPTION

The AD8260 includes a high current driver, usable as a dynamic range, it is essential that the part be ac-coupled when transmitter, and a low noise digitally programmable variable operating on a single supply.

gain amplifier (DGA), useable as a receiver.

The AD8260 preamplifier (Pr A) is configured with external The receiver section consists of a single-ended input preampli- resistors for gains greater than 6 d B and can be inverting or fier, and linear-in-d B, differential-output DGA. The receiver has noninverting. The DGA is characterized with a noninverting a small signal –3 d B bandwidth of 230 MHz; the driver small preamplifier gain of 2×. The attenuator has a range of 30 d B and signal bandwidth is 195 MHz. The driver delivers ±300 m A, the output amplifier has a gain of 8× (18.06 d B). The lowest well suited for driving low impedance loads, even when noninverting gain range is −6 d B to +24 d B and shifts up with connected to a 3.3 V supply. increased preamplifier gain. The gain is controlled via a parallel

port (Pin GNS0 to Pin GNS3) with 10 gain steps of 3 d B per 2-

The AD8260 DGA is ideal for trim applications and has a gain

code. The preamplifier and DGA are disabled for any code that

span of 30 d B, in 3 d B steps. Excellent bandwidth uniformity is

is not assigned a gain step.

maintained across the entire frequency range. The low output-

referred noise of the DGA is advantageous in driving high The AD8260 can operate with single or dual supplies from 3.3 V speed ADCs. The differential output facilitates the interface to to ±5 V. An internal buffer normally provides a split supply modern low voltage high speed ADCs. reference for single-supply operation; an external reference can also be used when the VMID buffer is shut down.

Single-supply and dual-supply operation makes the part versatile and enables gain control of negative-going pulses, such as those The operating temperature range is −40°C to +105°C. The generated by photodiodes or photo-multiplier tubes, as well as AD8260 is available in a 5 mm × 5 mm, 32-lead LFCSP. processing band-pass signals on a single supply. For maximum

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