Active RC, 4th Order Lowpass Filter Family

The LTC1563-2/LTC1563-3 are a family of extremely easy-to-use, active RC lowpass filters with rail-to-rail inputs and outputs and low DC offset suitable for systems with a resolution of up to 16 bits. The LTC1563-2, with a single resistor value, gives a unity-gain Butterworth response. The LTC1563-3, with a single resistor value, gives a unity-gain Bessel response. The proprietary architecture of these parts allows for a simple resistor calculation:

R = 10k (256kHz/fC); fC = Cutoff Frequency

where fC is the desired cutoff frequency. For many applications, this formula is all that is needed to design a filter. By simply utilizing different valued resistors, gain and other responses are achieved.

The LTC1563-X features a low power mode, for the lower frequency applications, where the supply current is reduced by an order of magnitude and a near zero power shutdown mode.

The LTC1563-Xs are available in the narrow SSOP-16 package (Same footprint as an SO-8 package).

Applications

* Discrete RC Active Filters and Modules

* Antialiasing Filters

* Smoothing or Reconstruction Filters

* Linear Phase Filtering for Data Communication

* Phase Locked Loops

* Extremely Easy to Use—A Single Resistor Value Sets the Cutoff Frequency (256Hz < fC < 256kHz)

* Extremely Flexible—Different Resistor Values Allow Arbitrary Transfer Functions with or without Gain (256Hz < fC < 256kHz)

* Supports Cutoff Frequencies Up to 360kHz Using FilterCAD™

* LTC1563-2: Unity-Gain Butterworth Response Uses a Single Resistor Value, Different Resistor Values Allow Other Responses with or without Gain

* LTC1563-3: Unity-Gain Bessel Response Uses a Single Resistor Value, Different Resistor Values Allow Other Responses with or without Gain

* Rail-to-Rail Input and Output Voltages

* Operates from a Single 3V (2.7V Min) to ±5V Supply

* Low Noise: 36µVRMS for fC = 25.6kHz, 60µVRMS for fC = 256kHz

* fC Accuracy < ±2% (Typ)

* DC Offset < 1mV

* Cascadable to Form 8th Order Lowpass Filters

* Available in Narrow SSOP-16 Package