New tool from Intersil simplifies active filter design

Depending on the quality of the models, the simulation results fit the circuit’s behavior.

Intersil’s new "ActiveFilter Designer" tool helps the designer already at the very beginning of a filter design. No more time-consuming calculating of resistors’ and capacitors’ values – the tool will do it for the designer. It is that comfortable that even capacitor values will be taken from the E24 series only and resistor values will then be adjusted automatically. As of today, the tool supports only low-pass filters, but other types will follow.

The tool supports a very wide range of requirements such as cut-off frequencies from 5kHz to 50MHz (seven decades), filters up to 6th order, and gains up to 10. However, the gain can be up to 125 for a three-stage filter in the manual design flow. Each stage consists of a 1 st or 2 nd order filter which implies that there can be up to three amplifier stages. All popular filter shapes such as Butterworth, Bessel, Chebychev with different ripple values can be selected. It is also possible to enter the filter poles directly in case none of these filter shapes meet the designer’s requirements.

The "Active Filter Designer" tool can be found on Intersil’s Internet site after clicking iSim Online Design Simulation. It is the first entry in the list of simulations for operation amplifiers. Users need to register first. The browser settings must allow Java scripts, pop-up windows and cookies, and the Flash Player 8 or higher must be installed.

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