Active Filter Demo Board Kit User’s Guide © 2006 Microchip Technology Inc.
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ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Table of Contents Preface ........................................................................................................................... 1 Introduction............................................................................................................ 1 Document Layout .................................................................................................. 1 Conventions Used in this Guide ...............................................
Active Filter Demo Board Kit User’s Guide Appendix A. Schematics and Layouts ......................................................................31 A.1 Introduction .................................................................................................. 31 A.2 VDD/2 Filter Section (Sub-Assembly #: 102-00098R1) ................................ 31 A.3 Active Filter Section (Sub-Assembly #: 102-00097R1) ................................ 34 A.4 Accessory Bag (Sub-Assembly #: 110-00097R1) ............
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Preface NOTICE TO CUSTOMERS All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site (www.microchip.com) to obtain the latest documentation available. Documents are identified with a “DS” number.
Active Filter Demo Board Kit User’s Guide CONVENTIONS USED IN THIS GUIDE This manual uses the following documentation conventions: DOCUMENTATION CONVENTIONS Description Arial font: Italic characters Represents Referenced books Emphasized text A window A dialog A menu selection A field name in a window or dialog A menu path MPLAB® IDE User’s Guide ...is the only compiler...
Preface RECOMMENDED READING This user's guide describes how to use Active Filter Demo Board Kit. Other useful documents are listed below. The following Microchip documents are available and recommended as supplemental reference resources. MCP6271 Data Sheet (DS21810) Gives detailed information on the op amps that are included in the Active Filter Demo Board Kit Accessory Bag. FilterLab® 2.0 User’s Guide (DS51419) Covers the functionality of Microchip’s active filter design software.
Active Filter Demo Board Kit User’s Guide NOTES: DS51614A-page 4 © 2006 Microchip Technology Inc.
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Chapter 1. Product Overview 1.1 INTRODUCTION The Active Filter Demo Board Kit is described by the following: • Assembly # : 114-00097R1 • Order # : MCP6XXXDM-FLTR • Name: Active Filter Demo Board Kit Items discussed in this chapter include: • • • • • 1.
Active Filter Demo Board Kit User’s Guide 1.3 INTENDED USE OF THE ACTIVE FILTER DEMO BOARD KIT This kit is intended to support active filters designed by FilterLab® V2.0 (see Section 1.6 “Associated Tools”). These filters are all pole and are built by cascading first and second order sections. Higher frequency filters (e.g., a low-pass filter with cutoff at 1 MHz) can have their design initially verified on these boards; see Section 4.5 “Higher Frequency Filters”. 1.
Product Overview Figure 1-2 shows the Active Filter Demo Board Kit’s five PCBs; one VDD/2 Filter Section PCB and four Active Filter Section PCB’s. It shows how these boards are cascaded (using board connectors), and how lab equipment can be attached (via test points) to measure the filter response.
Active Filter Demo Board Kit User’s Guide 1.6 ASSOCIATED TOOLS FilterLab 2.0® is an innovative software tool that simplifies active (op amp) filter design. Available at no cost from Microchip’s web site (www.microchip.com), the FilterLab 2.0 active filter software design tool provides full schematic diagrams of the filter circuit with component values, displays the frequency response, and gives a SPICE listing for further simulations. Users can select a low-pass, band-pass or high-pass response.
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Chapter 2. Setup and Installation 2.1 INTRODUCTION This chapter shows how to set up the Active Filter Demo Board Kit. Items discussed in this chapter include: • • • • • 2.2 Required Tools Connecting the PCBs VDD/2 Filter Section Set-up Active Filter Section Set-up Set-up Verification REQUIRED TOOLS • Lab power supply • Lab signal source (e.g., function generator) • Lab measurement equipment (e.g., oscilloscope) 2.
Active Filter Demo Board Kit User’s Guide The user provides the supply voltages, which need to be in the allowed range for the installed op amps. Any of Microchip’s op amps that operate below 5.5V can be used; higher voltage parts can be accommodated (see Section 4.2 “Power Supplies”). Five MCP6271 op amps are included in the accessory bag for convenience. The power lines are bypassed by 1.0 µF capacitors at each board input. The op amps also have 0.1 µF local bypass capacitors. 2.
Setup and Installation VDD VDD/2 VDD VDD/2 GND GND GND VIN GND GND FIGURE 2-3: 2.5 VOUT GND VDD/2 Filter Section Top View. ACTIVE FILTER SECTION SET-UP The filter sections designed by FilterLab V2.0 have several topologies. This section details the conversion of these topologies to the Active Filter Demo Board Kit. Figure 2-4 shows the circuit diagram for the Active Filter Section. P1 VDD J2 C1 1.0 µF VDD/2 C2 0.1 µF R1 10Ω GND GND VOUT TP1 GND U1 MCP6271 C3 GND 0.
Active Filter Demo Board Kit User’s Guide The Active Filter Section is shown in Figure 2-5. The single op amp U1 can have either a PDIP-8 or SOIC-8 package: • PDIP-8 packages are inserted into the DIP-8 socket to the right of the U1 label • SOIC-8 packages can be accommodated; see Section 4.
Setup and Installation 2.5.1 FilterLab Circuit Topology vs. PCB Reference Designators FilterLab V2.
Active Filter Demo Board Kit User’s Guide 2.5.
Setup and Installation 2.5.
Active Filter Demo Board Kit User’s Guide 2.5.
Setup and Installation 2.6 SET-UP VERIFICATION 1. Install components (resistors, capacitors, and op amps) for a filter design (e.g., the filter described in Section 3.2 “The Filter Design” and Section 3.3 “Putting the Filter Together”). 2. Verify the power supply voltages, including VDD/2, for all of the boards. 3. Test the filter response as described in Section 3.4 “Testing the Filter”. © 2006 Microchip Technology Inc.
Active Filter Demo Board Kit User’s Guide NOTES: DS51614A-page 18 © 2006 Microchip Technology Inc.
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Chapter 3. Building the Filter Supplied in the Kit 3.1 INTRODUCTION The accessory bag that comes with this kit makes it quick and easy to evaluate the filter described below; it was designed in FilterLab V2.0. Items discussed in this chapter include: • The Filter Design • Putting the Filter Together • Testing the Filter 3.2 THE FILTER DESIGN See Figure 3-1 for the circuit diagram supported by the accessory bag.
Active Filter Demo Board Kit User’s Guide 0 -10 Gain (dB) -20 Measured -30 Nominal Simulation -40 -50 -60 -70 MCP601 Op Amps -80 10 FIGURE 3-2: 3.3 100 Frequency (Hz) 1,000 Filter Frequency Response. PUTTING THE FILTER TOGETHER Each of the components in Figure 3-1 that needs to be inserted in a socket is listed in Table 3-1 (see Table B-5). This table gives the section number (see Section 2.5 “Active Filter Section Set-up”) and the PCB reference designators (e.g., Z5).
Building the Filter Supplied in the Kit Figure 3-3 is a picture of the fully assembled filter shown in Figure 3-1. Note that the board on the left (VDD/2 Filter Section) provides an easy way to connect the input signal source and power supply to the filter. JP1 on this board may be connected to INT or EXT in this case. FIGURE 3-3: Kit. 3.4 Picture of the Filter Supported by the Active Filter Demo Board TESTING THE FILTER 3.4.1 DC Bias Figure 3-4 shows the most important DC bias voltages to check.
Gain Spread (dB) Active Filter Demo Board Kit User’s Guide 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 100 MC Sims 1% R's 5% C's -3.3 sigma 10 100 Frequency (Hz) 1,000 Gain Error (Monte Carlo simulation) vs. Frequency. 110 108 106 104 102 100 98 96 94 100 MC Sims 1% R's 5% C's 92 26% 24% 22% 20% 18% 16% 14% 12% 10% 8% 6% 4% 2% 0% 90 Percentage of Occurrences FIGURE 3-5: +3.3 sigma Pass-Band Frequency at -3.
Building the Filter Supplied in the Kit 0 -10 Gain (dB) -20 -30 VOUT: U1 U2 U3 -40 -50 -60 MCP601 Op Amps Nominal Simulation -70 -80 10 FIGURE 3-7: 100 Frequency (Hz) 1,000 Frequency Response for All Outputs. Figure 3-8 shows the step response of the filter in Figure 3-1. The output of U2 (the second op amp) shows the largest overshoot, so it limits the output voltage range of the filter. The nominal overshoot is 6.1% (0.18V for a 3.0V step). Section Output Voltages (V) 4.5 VIN 4.
Active Filter Demo Board Kit User’s Guide NOTES: DS51614A-page 24 © 2006 Microchip Technology Inc.
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Chapter 4. Common Filter Modifications 4.1 INTRODUCTION The modifications described in this chapter include: • • • • • 4.2 Power Supplies Filter Section Ordering for Noise and Headroom Combining Low-pass and High-pass Sections Higher Frequency Filters Using 8-Pin SOIC Op Amps POWER SUPPLIES 4.2.
Active Filter Demo Board Kit User’s Guide To implement dual supplies, it is also necessary to change the Active Filter Section (see Figure 4-2) set-up: • The boards’ bypass capacitors (C1 and C3) need to be removed and replaced - Connect one set from –VS (board GND) to GND (board VDD/2) - Connect the other set from +VS (board VDD) to GND (board VDD/2).
Common Filter Modifications 4.3 FILTER SECTION ORDERING FOR NOISE AND HEADROOM FilterLab V2.0 orders the filter sections for good dynamic range performance. Its default selections are: • Section pole quality factors (QP) are ordered from lowest to highest (from Section # 1 to Section # 4) - In other words, section damping factors (ζ = 0.
Active Filter Demo Board Kit User’s Guide 4.6 USING 8-PIN SOIC OP AMPS There are two options available when using single op amps in SOIC-8 packages (150 mil wide); soldering onto the VDD/2 Filter Section and/or Active Filter Section board(s) or soldering it onto a separate board which is connected to the DIP-8 socket. Note: The DIP-8 socket must be empty; only one op amp can be used at a time. Figure 4-3 shows a SOIC-8 op amp soldered onto the Active Filter Section Board. FIGURE 4-3: Board.
Common Filter Modifications FIGURE 4-5: © 2006 Microchip Technology Inc. Connecting Adaptor Board onto Active Filter Section.
Active Filter Demo Board Kit User’s Guide NOTES: DS51614A-page 30 © 2006 Microchip Technology Inc.
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Appendix A. Schematics and Layouts A.1 INTRODUCTION This appendix contains the schematics and layouts for the different pieces of the Active Filter Demo Board Kit Sub-assemblies: • VDD/2 Filter Section (Sub-Assembly # : 102-00098R1) • Active Filter Section (Sub-Assembly # : 102-00097R1) • Accessory Bag (Sub-Assembly # : 110-00097R1) A.2 VDD/2 FILTER SECTION (SUB-ASSEMBLY #: 102-00098R1) A.2.1 Circuit See Figure A-1 for the VDD/2 Filter Section circuit diagram.
M Active Filter Demo Board Kit User’s Guide FIGURE A-1: DS51614A-page 32 VDD/2 Filter Section – Schematic. © 2006 Microchip Technology Inc.
Schematics and Layouts A.2.2 Board Plots The Gerber files for this board are available on the Microchip website (www.microchip.com) and are contained in the zip file “00098R1 Gerbers.zip”. FIGURE A-2: VDD/2 Filter Section – Top Silk Screen. FIGURE A-3: VDD/2 Filter Section – Top Metal Layer. © 2006 Microchip Technology Inc.
Active Filter Demo Board Kit User’s Guide FIGURE A-4: A.3 VDD/2 Filter Section – Bottom Metal Layer. ACTIVE FILTER SECTION (SUB-ASSEMBLY #: 102-00097R1) A.3.1 Circuit See Figure A-5 for the VDD/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.
M Schematics and Layouts FIGURE A-5: Active Filter Section – Schematic. © 2006 Microchip Technology Inc.
Active Filter Demo Board Kit User’s Guide A.3.2 Board Plots The Gerber files for this board are available on the Microchip website (www.microchip.com) and are contained in the zip file “00097R1 Gerbers.zip”. DS51614A-page 36 FIGURE A-6: Active Filter Section – Top Silk-Screen. FIGURE A-7: Active Filter Section – Top Metal Layer. © 2006 Microchip Technology Inc.
Schematics and Layouts FIGURE A-8: A.4 Active Filter Section – Bottom Metal Layer. ACCESSORY BAG (SUB-ASSEMBLY #: 110-00097R1) See Figure 3-1 for the circuit diagram supported by this Accessory Bag. This filter is a Bessel low-pass with n = 5, fC = 100 Hz, and Gain = 1 V/V. It uses single supply, Sallen-Key sections. See Section B.3 “Accessory Bag BOM” for the Bill of Material for this filter. These components are placed in an ESD separate ESD bag.
Active Filter Demo Board Kit User’s Guide NOTES: DS51614A-page 38 © 2006 Microchip Technology Inc.
ACTIVE FILTER DEMO BOARD KIT USER’S GUIDE Appendix B. Bill Of Materials (BOM) B.1 VDD/2 FILTER SECTION BOMS The BOM in Table B-1 corresponds to Figure 2-2. Unpopulated parts are in Table B-2. TABLE B-1: BILL OF MATERIALS (102-00098R1) Qty Reference Description Manufacturer Part Number ® 2 C3, C4 100 nF, 50V, 10%, X7R, 0805 SMD, Ceramic Kemet Electronics C0805C104K5RACTU 2 C1, C2 1.0 µF, 16V, 10%, X7R, 0805 SMD, Ceramic Kemet Electronics C0805C105K4RACTU 1 JP1 Header, 2 × 2, 0.
Active Filter Demo Board Kit User’s Guide B.2 ACTIVE FILTER SECTION BOM The BOM in Table B-3 corresponds to the circuit in Figure 2-4, which is repeated four times. Unpopulated parts are in Table B-4. TABLE B-3: BILL OF MATERIALS (102-00097R1) (NOTE 3) Qty Referenc (Note 1) e Manufacturer Part Number 8 C2, C3 100 nF, 50V, 10%, X7R, 0805 SMD, Ceramic Kemet Electronics C0805C104K5RACTU 4 C1 1.
Bill Of Materials (BOM) B.3 ACCESSORY BAG BOM The BOM in Table B-5 corresponds to the collection of resistors, capacitors, and MCP6271 op amps that comes in the Accessory Bag which is shipped in the Active Filter Demo Board Kit. It includes enough op amps and jumpers to support any reasonable filter design. It also supports the circuit in ”Chapter 3. “Building the Filter Supplied in the Kit”. Other filters may need tighter tolerance resistors and capacitors (i.e., 1% or 2%).
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