Maplesim Introductory Demo: Sallen Key Filter

MapleSim Introductory Demo: Sallen Key Filter

Confidential

© Maplesoft, a division of Waterloo Maple Inc., 2007

Step 1: Creating a Low-pass Filter

Components needed:

-Resistor -found in the Electrical\Analog\Common palette

-Capacitor -found in the Electrical\Analog\Common palette

-Ground -found in the Electrical\Analog\Common palette

-Ideal Op Amp 3pin-found in the Electrical\Analog\Common palette

What to do:

-To make the low-pass filter version of the Sallen Key filter, drag each component onto the workspace and connect the components to make the circuit below (figure 1).

-In this step and the next, the circuit connections are not overlapping so that it is more obvious where the connections are being made. Although, when drawing this circuit, you can choose to overlap the lines to make the circuit look cleaner.

-The resistor that is connected to the output of the Op Amp is considered the load for the filter.

Figure 1: Sallen Key Low-pass filter

Step 2: Creating a High-pass Filter

Components needed:

-Resistor -found in the Electrical\Analog\Common palette

-Capacitor -found in the Electrical\Analog\Common palette

-Ground -found in the Electrical\Analog\Common palette

-Ideal Op Amp 3pin-found in the Electrical\Analog\Common palette

What to do:

-To make the high-pass filter version of the Sallen Key filter, drag each component onto the workspace and connect the components to make the circuit below.

-Just like the low-pass filter, the resistor to the right of the Op Amp is the load for the filter.

Figure 2: Sallen Key low-pass and high-pass filter

Step 3: Adding the Signal Source

Components needed:

-Signal Voltage-found in the Electrical\Analog\Sources\Voltage palette

-Ground -found in the Electrical\Analog\Common palette

-Sine-found in the Signal Blocks\Sources\Real palette

What to do:

-Drag the Signal Voltage, Sine and Ground components into the MapleSim environment, placing them to the left of the two filters. Connect the components together. The Signal Voltage is hooked up as the input for both the high-pass and low-pass filter.

Figure 3: Circuit after a voltage input is included

Step 4: Add Probes and Simulate

Components needed:

-N\A

What to do:

-Right click on the line connecting the filters to the loads and add probes that will output the voltages.

-Simulate the model

-To investigate the behavior of these filters, delete the Sine input and choose another real signal like the Pulse and Saw Tooth signals found in the Signal Blocks\Sources\Real palette.

Figure 4: Completed Demo circuit

Figure 5: Plot output of the two filters to a Sine input