LT1568 - Very Low Noise, High Frequency Active RC, Filter Building Block

Features

  • Up to 10MHz Center Frequency on a Single 3V Supply
  • Easy to Use—A Single Resistor Value Sets Lowpass Cutoff Frequency (200kHz <= f C <= 5MHz)
  • Unequal Resistor Values Extend Cutoff Frequency Up to 10MHz
  • Extremely Flexible—Different Resistor Values Allow Lowpass Transfer Functions with or Without Gain
  • SNR = 92dB (fC = 2MHz, 2VP-P)
  • THD = –84dB (fC = 2MHz, 1VP-P)
  • Internal Capacitors Trimmed to ±0.75%
  • Single 4-Pole Lowpass Filter or Matched Pair of 2-Pole Lowpass Filters
  • Can be Connected as a Bandpass Filter
  • Single-Ended or Differential Output
  • Operates from Single 3V (2.7V Min) to ±5V Supply
  • Rail-to-Rail Input and Output Voltages

Typical Application

LT1568 Typical Application
LT1568 Typical Application

Description

The LT1568 is an easy-to-use, active-RC filter building block with rail-to-rail inputs and outputs. The internal capacitors of the IC and the GBW product of the internal low noise op amps are trimmed such that consistent and repeatable filter responses can be achieved. With a single resistor value, the LT1568 provides a pair of matched 2-pole Butterworth lowpass filters with unity gain suitable for I/Q channels.

By using unequal-valued external resistors, the two 2-pole sections can create different frequency responses or gains. In addition, the two stages may be cascaded to create a single 4-pole filter with a programmable response. Capable of cutoff frequencies up to 10MHz, the LT1568 is ideal for antialiasing or channel filtering in high speed data communications systems. The LT1568 can also be used as a bandpass filter.

The LT1568 features very low noise, supporting signal-to-noise ratios of over 90dB. It also provides single-ended to differential signal conversion for directly driving high speed A/D converters. The LT1568 has a shutdown mode that reduces supply current to approximately 0.5mA on a 5V supply.

The LT1568 is available in a narrow 16-lead SSOP package.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT1568CGN#PBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LT1568CGN#TRPBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LT1568IGN#PBF SSOP-16 GN I 05-08-1641 (GN16) Yes
LT1568IGN#TRPBF SSOP-16 GN I 05-08-1641 (GN16) Yes


LT1568 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT1568CGN#PBF SSOP-16 C $5.20 $4.25 Yes
LT1568CGN#TRPBF SSOP-16 C $4.31 Yes
LT1568IGN#PBF SSOP-16 I $6.20 $5.10 Yes
LT1568IGN#TRPBF SSOP-16 I $5.16 Yes
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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 Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC675B LT1568CGN Demo Board | Active Filter Building Block IC Configured as 4th Order 500kHz Bandpass $50.00
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Click here to view our complete list of demo boards

Applications

  • Replaces Discrete RC Active Filters and LC Filter Modules
  • Antialiasing/Reconstruction Filters
  • Dual or I-and-Q Channels (Two Matched 2nd Order Filters in One Package)
  • Single-Ended to Differential Conversion
  • Video Signal Processing

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Design Tools

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LT1568

LT1568 Design Guide

The LT1568 is a dual amplifier block useful for creating high frequency active filters. Implementation of lowpass and bandpass filters over a frequency range of 100KHz to 10MHz can be achieved using only a few external resistors. This easy to use Excel based Design Guide crunches the numbers to calculate all of the external component values and provides a 'ready to build' schematic of the filter.

Technical Support