Microchip Technology MCP6XXXDM-FLTR User Manual
Active Filter Demo Board Kit User’s Guide
DS51614A-page 34
© 2006 Microchip Technology Inc.
FIGURE A-4:
V
DD
/2 Filter Section – Bottom Metal Layer.
A.3
ACTIVE FILTER SECTION (SUB-ASSEMBLY #: 102-00097R1)
A.3.1
Circuit
See Figure A-5 for the V
DD
/2 Filter Sections circuit diagram. The input and output
headers (J1, J2, P1, and P2) allow the PCBs to be cascaded as needed. The filter order
will determine how many of these boards need to be cascaded.
The impedances Z1 to Z11 are realized as resistors, capacitors, shorts or open circuits,
depending on the section topology. These components are placed in pin sockets.
Op amp U1 interacts with the impedances Z1 to Z11 to form an active filter section (one
or two pole). Op amp U1 is usually a single, PDIP-8 part inserted into the DIP-8 socket;
it can be a SOIC-8 that is soldered to the board (see U1A in Figure A-5).
C1 and C3 are bypass capacitors for V
will determine how many of these boards need to be cascaded.
The impedances Z1 to Z11 are realized as resistors, capacitors, shorts or open circuits,
depending on the section topology. These components are placed in pin sockets.
Op amp U1 interacts with the impedances Z1 to Z11 to form an active filter section (one
or two pole). Op amp U1 is usually a single, PDIP-8 part inserted into the DIP-8 socket;
it can be a SOIC-8 that is soldered to the board (see U1A in Figure A-5).
C1 and C3 are bypass capacitors for V
DD
. C2 is a bypass capacitor for V
DD
/2, and R1
is a snubber resistor that helps prevent capacitive loading problems for the op amp on
the V
the V
DD
/2 Filter Section.
The demonstration board includes test points for convenience on the bench. TP1
through TP3 make it possible to measure the output voltage of each filter section.
See Section B.1 “V
through TP3 make it possible to measure the output voltage of each filter section.
See Section B.1 “V
/2 Filter Section BOMs” for the Bill of Material for this kit.