Overview

Features and Benefits

  • Accurate Linear Gain Control: ±1% Typ, ±3% Max
  • Constant Gain with Temperature
  • Wide Bandwidth: 40MHz
  • High Slew Rate: 300V/µs
  • Fast Control Path: 10MHz
  • Low Control Feedthrough: 2.5mV
  • High Output Current: 40mA
  • Low Output Noise
    • 45nV/√Hz at AV = 1
    • 270nV/√Hz at AV = 100
  • Low Distortion: 0.01%
  • Wide Supply Range: ±2.5V to ±15V
  • Low Supply Current: 13mA
  • Low Differential Gain and Phase: 0.02%, 0.02°

Product Details

The LT1251/LT1256 are 2-input, 1-output, 40MHz current feedback amplifiers with a linear control circuit that sets the amount each input contributes to the output. These parts make excellent electronically controlled variable gain amplifiers, filters, mixers and faders. The only external components required are the power supply bypass capacitors and the feedback resistors. Both parts operate on supplies from ±2.5V (or single 5V) to ±15V (or single 30V).

Absolute gain accuracy is trimmed at wafer sort to minimize part-to-part variations. The circuit is completely temperature compensated.

The LT1251 includes circuitry that eliminates the need for accurate control signals around zero and full scale. For control signals of less than 2% or greater than 98%, the LT1251 sets one input completely off and the other completely on. This is ideal for fader applications because it eliminates off-channel feed through due to offset or gain errors in the control signals.

The LT1256 does not have this on/off feature and operates linearly over the complete control range. The LT1256 is recommended for applications requiring more than 20dB of linear control range.

Applications

  • Composite Video Gain Control
  • RGB, YUV Video Gain Control
  • Video Faders, Keyers
  • Gamma Correction Amplifiers
  • Audio Gain Control, Faders
  • Multipliers, Modulators
  • Electronically Tunable Filters

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Tools & Simulations

LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

LTspice

Models for the following parts are available in LTspice:

LT1256

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

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The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


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