LT1468
Linear Technology
Using Linear Technology’s LT1468 op amp and the LT5400A-3:
Design DocumentAnalog
Precision Matched Resistors Automatically Improve Differential Amplifier CMRR
Explains how the LT5400 quad matched resistor network improves CMRR in differential circuits using the unique 'Matching for CMRR' specification and provides circuit derivations.
Overview
This design note details the relationship between resistor matching and Common Mode Rejection Ratio (CMRR) in differential, instrumentation, and difference amplifier circuits. It introduces the LT5400 series of quad matched resistor networks, highlighting the 'Matching for CMRR' specification which simplifies the prediction of CMRR performance. The document provides step-by-step mathematical derivations for calculating the total CMRR of a circuit by accounting for both the amplifier's finite CMRR and the resistor network's matching tolerances. It includes specific calculation examples featuring the LTC2053 instrumentation amplifier and the LT5400A-1 resistor network.
Use Cases
- Precision differential signal processing
- High-performance instrumentation amplifier design
- Sensor signal conditioning
- Data acquisition systems
- Medical electronics
Topics
LT5400
LT5400A
LTC2053
CMRR
Matched Resistors
Differential Amplifier
Instrumentation Amplifier
Common Mode Rejection Ratio
LT5400A-1
Linear Technology
Referenced Parts
LT5400
Linear Technology
Only the LT5400 offers a Matching for CMRR, (ΔR/R)CMRR specification.
LT5400A
Linear Technology
For example, the LT5400A offers 0.01% resistor matching and Matching for CMRR of 0.005%.
LT5400A-1
Linear Technology
Using Linear Technology’s LTC2053 Instrument Amplifier, configured for a gain of 1, and the LT5400A-1:
LT5400A-3
Linear Technology
Using Linear Technology’s LT1468 op amp and the LT5400A-3:
LTC2053
Linear Technology
Using Linear Technology’s LTC2053 Instrument Amplifier, configured for a gain of 1
| LT1468 | Linear Technology | Using Linear Technology’s LT1468 op amp and the LT5400A-3: |
| LT5400 | Linear Technology | Only the LT5400 offers a Matching for CMRR, (ΔR/R)CMRR specification. |
| LT5400A | Linear Technology | For example, the LT5400A offers 0.01% resistor matching and Matching for CMRR of 0.005%. |
| LT5400A-1 | Linear Technology | Using Linear Technology’s LTC2053 Instrument Amplifier, configured for a gain of 1, and the LT5400A-1: |
| LT5400A-3 | Linear Technology | Using Linear Technology’s LT1468 op amp and the LT5400A-3: |
| LTC2053 | Linear Technology | Using Linear Technology’s LTC2053 Instrument Amplifier, configured for a gain of 1 |