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AN951
| Title |
Title
Amplifying High-Impedence Sensors ? Photodiode Example
|
|---|---|
| Name |
Name
AN951
|
| Date |
Date
06/24/2015
|
| Application Categories |
Application Categories
Medical /
Homecare Pulse Oximeter
Signal Conditioning & Measurement /
Amplification (Op Amps)
|
| Product Categories |
Product Categories
Linear Devices /
Programmable Gain Amplifiers (PGA)
|
| Description |
Description
Embedded systems contain many types of sensors, used to sense events in the real world. They can be classified according to the role they play in the analog conditioning circuitry, such as voltage source, current source, resistive and capacitive (frequency-based). This application note discusses the analog conditioning circuit used for high-impedance sensors that act like current sensors. Current sensors connect to a transimpedance amplifier which converts current to voltage. The design approach illustrated in this application note, using op amps, is broken down into four design steps: DC, stability compensation, closed-loop gain and noise reduction. A design using a PIN photodiode (light detector) illustrates the principles discussed. Measurement results are provided to support the theory presented. The last sections of this application note contain supplemental information. The References section contains references to pertinent literature, while Appendix A: ?Op Amp Stability Analysis? covers op amp stability analysis. Finally, Appendix B: ?Set-up Overview? discusses the tools used to measure the design.
|
Development Tools
| Title | Part Number | Title | |
|---|---|---|---|
|
MCP6SX2DM-PCTLPD
MCP6SX2 PGA PHOTODIODE PICTAIL DEMO BOARD
|
|
MCP6SX2DM-PCTLPD | MCP6SX2 PGA PHOTODIODE PICTAIL DEMO BOARD |
|
MCP6031DM-PTPLS
MCP6031 PHOTODIODE PICTAIL PLUS DEMO BOARD
|
|
MCP6031DM-PTPLS | MCP6031 PHOTODIODE PICTAIL PLUS DEMO BOARD |
Silicon Products
| Title | Product | Title |
|---|---|---|
|
MCP609
2.5V to 6.0V Micropower CMOS Op Amp
|
MCP609 | 2.5V to 6.0V Micropower CMOS Op Amp |
|
MCP6231U
20 µA, 300 kHz Rail-to-Rail Op Amp
|
MCP6231U | 20 µA, 300 kHz Rail-to-Rail Op Amp |
|
MCP6054
30 µA, High Precision Op Amps
|
MCP6054 | 30 µA, High Precision Op Amps |
|
MCP6G01U
110 µA Selectable Gain Amplifier
|
MCP6G01U | 110 µA Selectable Gain Amplifier |
|
MCP6S93
Single-Ended, Rail-to-Rail I/O, Low-Gain PGA
|
MCP6S93 | Single-Ended, Rail-to-Rail I/O, Low-Gain PGA |
|
MCP6284
450 µA, 5 MHz Rail-to-Rail Op Amp
|
MCP6284 | 450 µA, 5 MHz Rail-to-Rail Op Amp |
|
MCP6244
50 µA, 550 kHz Rail-to-Rail Op Amp
|
MCP6244 | 50 µA, 550 kHz Rail-to-Rail Op Amp |
|
TC7650
Chopper Stabilized Operational Amplifier
|
TC7650 | Chopper Stabilized Operational Amplifier |
| TC1030 | TC1030 | |
| TC1035 | TC1035 | |
|
MCP6024
Rail-to-Rail Input/Output, 10 MHz Op Amps
|
MCP6024 | Rail-to-Rail Input/Output, 10 MHz Op Amps |
|
MCP6G04
110 µA Selectable Gain Amplifier
|
MCP6G04 | 110 µA Selectable Gain Amplifier |
|
MCP6S26
Single-Ended, Rail-to-Rail I/O, Low Gain PGA
|
MCP6S26 | Single-Ended, Rail-to-Rail I/O, Low Gain PGA |
|
MCP604
2.7V to 6.0V Single Supply CMOS Op Amps
|
MCP604 | 2.7V to 6.0V Single Supply CMOS Op Amps |
|
MCP6234
20 µA, 300 kHz Rail-to-Rail Op Amp
|
MCP6234 | 20 µA, 300 kHz Rail-to-Rail Op Amp |
|
MCP6271R
170 µA, 2 MHz Rail-to-Rail Op Amp
|
MCP6271R | 170 µA, 2 MHz Rail-to-Rail Op Amp |
| TC1029 | TC1029 | |
| TC1026 | TC1026 | |
|
MCP6S28
Single-Ended, Rail-to-Rail I/O, Low Gain PGA
|
MCP6S28 | Single-Ended, Rail-to-Rail I/O, Low Gain PGA |
| TC911A | TC911A | |
|
MCP6064
60 µA, High Precision Op Amps
|
MCP6064 | 60 µA, High Precision Op Amps |
|
MCP6G01R
110 µA Selectable Gain Amplifier
|
MCP6G01R | 110 µA Selectable Gain Amplifier |
|
MCP6291R
1.0 mA, 10 MHz Rail-to-Rail Op Amp
|
MCP6291R | 1.0 mA, 10 MHz Rail-to-Rail Op Amp |
|
MCP6281R
450 µA, 5 MHz Rail-to-Rail Op Amp
|
MCP6281R | 450 µA, 5 MHz Rail-to-Rail Op Amp |
|
MCP665
60 MHz, 32 V/µs Rail-to-Rail Output Op Amp
|
MCP665 | 60 MHz, 32 V/µs Rail-to-Rail Output Op Amp |
|
MCP6231R
20 µA, 300 kHz Rail-to-Rail Op Amp
|
MCP6231R | 20 µA, 300 kHz Rail-to-Rail Op Amp |
| TC1034 | TC1034 | |
|
MCP6074
110 µA, High Precision Op Amps
|
MCP6074 | 110 µA, High Precision Op Amps |
|
MCP6034
0.9 µA, High-Precision Op Amps
|
MCP6034 | 0.9 µA, High-Precision Op Amps |
|
MCP6044
600 nA, Rail-to-Rail Input/Output Op Amps
|
MCP6044 | 600 nA, Rail-to-Rail Input/Output Op Amps |
|
MCP6241R
50 µA, 550 kHz Rail-to-Rail Op Amp
|
MCP6241R | 50 µA, 550 kHz Rail-to-Rail Op Amp |
|
MCP619
2.3V to 5.5V Micropower Bi-CMOS Op Amps
|
MCP619 | 2.3V to 5.5V Micropower Bi-CMOS Op Amps |
|
MCP6022
Rail-to-Rail Input/Output, 10 MHz Op Amps
|
MCP6022 | Rail-to-Rail Input/Output, 10 MHz Op Amps |
|
MCP602
2.7V to 6.0V Single Supply CMOS Op Amps
|
MCP602 | 2.7V to 6.0V Single Supply CMOS Op Amps |
|
MCP601
2.7V to 6.0V Single Supply CMOS Op Amps
|
MCP601 | 2.7V to 6.0V Single Supply CMOS Op Amps |
|
MCP6V02
300 µA, Auto-Zeroed Op Amps
|
MCP6V02 | 300 µA, Auto-Zeroed Op Amps |
|
MCP6042
600 nA, Rail-to-Rail Input/Output Op Amps
|
MCP6042 | 600 nA, Rail-to-Rail Input/Output Op Amps |
|
MCP6043
600 nA, Rail-to-Rail Input/Output Op Amps
|
MCP6043 | 600 nA, Rail-to-Rail Input/Output Op Amps |
|
MCP617
2.3V to 5.5V Micropower Bi-CMOS Op Amps
|
MCP617 | 2.3V to 5.5V Micropower Bi-CMOS Op Amps |
|
MCP6242
50 µA, 550 kHz Rail-to-Rail Op Amp
|
MCP6242 | 50 µA, 550 kHz Rail-to-Rail Op Amp |
|
MCP6231
20 µA, 300 kHz Rail-to-Rail Op Amp
|
MCP6231 | 20 µA, 300 kHz Rail-to-Rail Op Amp |
|
MCP6S91
Single-Ended, Rail-to-Rail I/O, Low-Gain PGA
|
MCP6S91 | Single-Ended, Rail-to-Rail I/O, Low-Gain PGA |
|
MCP6052
30 µA, High Precision Op Amps
|
MCP6052 | 30 µA, High Precision Op Amps |
|
MCP6441
450 nA, 9 kHz Op Amp
|
MCP6441 | 450 nA, 9 kHz Op Amp |
|
MCP6031
0.9 µA, High-Precision Op Amps
|
MCP6031 | 0.9 µA, High-Precision Op Amps |
|
MCP6G02
110 µA Selectable Gain Amplifier
|
MCP6G02 | 110 µA Selectable Gain Amplifier |
|
MCP6004
1 MHz, Low-Power Op Amp
|
MCP6004 | 1 MHz, Low-Power Op Amp |
|
MCP603
2.7V to 6.0V Single Supply CMOS Op Amps
|
MCP603 | 2.7V to 6.0V Single Supply CMOS Op Amps |
|
MCP6001
1 MHz, Low-Power Op Amp
|
MCP6001 | 1 MHz, Low-Power Op Amp |
|
MCP663
60 MHz, 32 V/µs Rail-to-Rail Output Op Amp
|
MCP663 | 60 MHz, 32 V/µs Rail-to-Rail Output Op Amp |
|
MCP607
2.5V to 6.0V Micropower CMOS Op Amp
|
MCP607 | 2.5V to 6.0V Micropower CMOS Op Amp |
|
MCP6142
600 nA, Non-Unity Gain Rail-to-Rail Input/Out
|
MCP6142 | 600 nA, Non-Unity Gain Rail-to-Rail Input/Out |
|
MCP6143
600 nA, Non-Unity Gain Rail-to-Rail Input/Out
|
MCP6143 | 600 nA, Non-Unity Gain Rail-to-Rail Input/Out |
|
MCP6283
450 µA, 5 MHz Rail-to-Rail Op Amp
|
MCP6283 | 450 µA, 5 MHz Rail-to-Rail Op Amp |
|
MCP6271
170 µA, 2 MHz Rail-to-Rail Op Amp
|
MCP6271 | 170 µA, 2 MHz Rail-to-Rail Op Amp |
|
MCP6272
170 µA, 2 MHz Rail-to-Rail Op Amp
|
MCP6272 | 170 µA, 2 MHz Rail-to-Rail Op Amp |
|
MCP6274
170 µA, 2 MHz Rail-to-Rail Op Amp
|
MCP6274 | 170 µA, 2 MHz Rail-to-Rail Op Amp |
|
MCP6241
50 µA, 550 kHz Rail-to-Rail Op Amp
|
MCP6241 | 50 µA, 550 kHz Rail-to-Rail Op Amp |
|
MCP6051
30 µA, High Precision Op Amps
|
MCP6051 | 30 µA, High Precision Op Amps |
|
MCP6032
0.9 µA, High-Precision Op Amps
|
MCP6032 | 0.9 µA, High-Precision Op Amps |
|
MCP6G03
110 µA Selectable Gain Amplifier
|
MCP6G03 | 110 µA Selectable Gain Amplifier |
|
MCP6G01
110 µA Selectable Gain Amplifier
|
MCP6G01 | 110 µA Selectable Gain Amplifier |
|
MCP6062
60 µA, High Precision Op Amps
|
MCP6062 | 60 µA, High Precision Op Amps |
|
TC7652
400 kHz, Single Zero-Drift Op Amp
|
TC7652 | 400 kHz, Single Zero-Drift Op Amp |
|
MCP6241U
50 µA, 550 kHz Rail-to-Rail Op Amp
|
MCP6241U | 50 µA, 550 kHz Rail-to-Rail Op Amp |
|
MCP6294
1.0 mA, 10 MHz Rail-to-Rail Op Amp
|
MCP6294 | 1.0 mA, 10 MHz Rail-to-Rail Op Amp |
| TC1043 | TC1043 | |
|
MCP6021
Rail-to-Rail Input/Output, 10 MHz Op Amps
|
MCP6021 | Rail-to-Rail Input/Output, 10 MHz Op Amps |
|
MCP6002
1 MHz, Low-Power Op Amp
|
MCP6002 | 1 MHz, Low-Power Op Amp |
|
MCP6V01
300 µA, Auto-Zeroed Op Amps
|
MCP6V01 | 300 µA, Auto-Zeroed Op Amps |
|
MCP6V06
300 µA, Auto-Zeroed Op Amps
|
MCP6V06 | 300 µA, Auto-Zeroed Op Amps |
|
MCP6V07
300 µA, Auto-Zeroed Op Amps
|
MCP6V07 | 300 µA, Auto-Zeroed Op Amps |
|
MCP6V03
300 µA, Auto-Zeroed Op Amps
|
MCP6V03 | 300 µA, Auto-Zeroed Op Amps |
|
MCP6V08
300 µA, Auto-Zeroed Op Amps
|
MCP6V08 | 300 µA, Auto-Zeroed Op Amps |
|
MCP662
60 MHz, 32 V/µs Rail-to-Rail Output Op Amp
|
MCP662 | 60 MHz, 32 V/µs Rail-to-Rail Output Op Amp |
|
MCP661
60 MHz, 32 V/µs Rail-to-Rail Output Op Amp
|
MCP661 | 60 MHz, 32 V/µs Rail-to-Rail Output Op Amp |
|
MCP608
2.5V to 6.0V Micropower CMOS Op Amp
|
MCP608 | 2.5V to 6.0V Micropower CMOS Op Amp |
|
MCP618
2.3V to 5.5V Micropower Bi-CMOS Op Amps
|
MCP618 | 2.3V to 5.5V Micropower Bi-CMOS Op Amps |
|
MCP6273
170 µA, 2 MHz Rail-to-Rail Op Amp
|
MCP6273 | 170 µA, 2 MHz Rail-to-Rail Op Amp |
|
MCP6232
20 µA, 300 kHz Rail-to-Rail Op Amp
|
MCP6232 | 20 µA, 300 kHz Rail-to-Rail Op Amp |
|
MCP6S92
Single-Ended, Rail-to-Rail I/O, Low-Gain PGA
|
MCP6S92 | Single-Ended, Rail-to-Rail I/O, Low-Gain PGA |
|
MCP6072
110 µA, High Precision Op Amps
|
MCP6072 | 110 µA, High Precision Op Amps |
|
MCP6144
600 nA, Non-Unity Gain Rail-to-Rail Input/Out
|
MCP6144 | 600 nA, Non-Unity Gain Rail-to-Rail Input/Out |
|
MCP6023
Rail-to-Rail Input/Output, 10 MHz Op Amps
|
MCP6023 | Rail-to-Rail Input/Output, 10 MHz Op Amps |
|
MCP6041
600 nA, Rail-to-Rail Input/Output Op Amps
|
MCP6041 | 600 nA, Rail-to-Rail Input/Output Op Amps |
|
MCP6141
600 nA, Non-Unity Gain Rail-to-Rail Input/Out
|
MCP6141 | 600 nA, Non-Unity Gain Rail-to-Rail Input/Out |
|
MCP606
2.5V to 6.0V Micropower CMOS Op Amp
|
MCP606 | 2.5V to 6.0V Micropower CMOS Op Amp |
|
MCP6281
450 µA, 5 MHz Rail-to-Rail Op Amp
|
MCP6281 | 450 µA, 5 MHz Rail-to-Rail Op Amp |
|
MCP6291
1.0 mA, 10 MHz Rail-to-Rail Op Amp
|
MCP6291 | 1.0 mA, 10 MHz Rail-to-Rail Op Amp |
|
MCP6293
1.0 mA, 10 MHz Rail-to-Rail Op Amp
|
MCP6293 | 1.0 mA, 10 MHz Rail-to-Rail Op Amp |
|
MCP6S21
Single-Ended, Rail-to-Rail I/O, Low Gain PGA
|
MCP6S21 | Single-Ended, Rail-to-Rail I/O, Low Gain PGA |
|
MCP6S22
Single-Ended, Rail-to-Rail I/O, Low Gain PGA
|
MCP6S22 | Single-Ended, Rail-to-Rail I/O, Low Gain PGA |
|
MCP616
2.3V to 5.5V Micropower Bi-CMOS Op Amps
|
MCP616 | 2.3V to 5.5V Micropower Bi-CMOS Op Amps |
|
MCP6282
450 µA, 5 MHz Rail-to-Rail Op Amp
|
MCP6282 | 450 µA, 5 MHz Rail-to-Rail Op Amp |
|
MCP6292
1.0 mA, 10 MHz Rail-to-Rail Op Amp
|
MCP6292 | 1.0 mA, 10 MHz Rail-to-Rail Op Amp |
|
MCP6285
450 µA, 5 MHz Rail-to-Rail Op Amp
|
MCP6285 | 450 µA, 5 MHz Rail-to-Rail Op Amp |
|
MCP6295
1.0 mA, 10 MHz Rail-to-Rail Op Amp
|
MCP6295 | 1.0 mA, 10 MHz Rail-to-Rail Op Amp |
|
MCP6275
170 µA, 2 MHz Rail-to-Rail Op Amp
|
MCP6275 | 170 µA, 2 MHz Rail-to-Rail Op Amp |
|
MCP6071
110 µA, High Precision Op Amps
|
MCP6071 | 110 µA, High Precision Op Amps |
|
MCP6033
0.9 µA, High-Precision Op Amps
|
MCP6033 | 0.9 µA, High-Precision Op Amps |
|
MCP6061
60 µA, High Precision Op Amps
|
MCP6061 | 60 µA, High Precision Op Amps |