User manual

Setup and Installation

2.5.1 FilterLab Circuit Topology vs. PCB Reference Designators

FilterLab V2.0 labels the capacitors and resistors in its circuit diagram as follows:

• R12 = Resistor, Section # 1, Resistor # 2 in that section

• C31 = Capacitor, Section # 3, Capacitor # 1 in that section

• Ra = Gain setting resistor for op amp in Sallen-Key Section # 1 (open, and not

labeled, when in unity gain)

• Rb = Feedback resistor for op amp in Sallen-Key Section # 1 (0Ω, and not

labeled, when in unity gain)

The resistor and capacitor reference designators on the Active Filter Section board

(Z1 - Z11) need to be filled according to FilterLab’s design. The following sub-sections

show how to convert from FilterLab’s circuit diagram to the PCB.

In the following, the PCBs are given section numbers 0 to 4:

• Section #0–for V

/2 Filter Section

• Section #1 to #4–for cascaded Active Filter Section

The different circuit topologies referred to in Section 2.5.2 “Sallen-Key, Low-pass Fil-

ter Sections”, Section 2.5.3 “Sallen-Key, High-pass Filter Sections”, and

Section 2.5.4 “Multiple Feedback, Low-pass and Band-pass Filter Sections” will

be labeled as shown in Figure 2-6.

FIGURE 2-6: Filter Section Labels.

AAA:

AAA-BB#-C

SK = Sallen-Key

MFB = Multiple Feedback

BB:

LP = Low-pass

BP = Band-pass

HP = High-pass

1 = Single, Real Pole

2 = Double, Complex Poles

“blank” = Sallen-Key Unity Gain Buffer (K = 1)

or Multiple Feedback

K = Sallen-Key Non-unity Gain Amplifier (K > 1)