AdvancedTopic 82 of 104Electronics & Embedded
Signal conditioning
Amplify, filter and level-shift sensor outputs before digitising.
In depth
Conditioning amplifies small signals, filters noise, shifts levels, linearises and protects inputs before the ADC. Bridges, instrumentation amplifiers, current-loop (4–20 mA), anti-alias filters and reference voltages are typical. Matching signal range to ADC span improves resolution.
Key points
- Bridge excitation
- Common-mode rejection
- Offset and gain trimming
ExampleA load cell with 2 mV/V sensitivity needs a precision amplifier.
Raw sensor outputs are small, noisy or shifted, so signal conditioning is needed before a converter can use them well.
What is Signal conditioning?
Amplify, filter and level-shift sensor outputs before digitising.
Why is it important to understand signal conditioning?
Raw sensor outputs are small, noisy or shifted, so signal conditioning is needed before a converter can use them well.
What is the purpose of level shifting?
It moves a signal's voltage range to match the input range of the next stage, such as the ADC or microcontroller.
Why are instrumentation amplifiers used for sensors?
They have high input impedance and high common-mode rejection, which suits small differential signals from bridges and thermocouples.
How is Signal conditioning used in practice?
Typical applications include amplifying a thermocouple voltage before an ADC, filtering a noisy strain gauge output with a low-pass stage and shifting a sensor's output range to fit the ADC input range.
What should I learn before Signal conditioning?
Study "Sensors" first (topic 81 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
What are the key points of Signal conditioning?
Bridge excitation. Common-mode rejection. Offset and gain trimming.
Can you give an example of Signal conditioning?
A load cell with 2 mV/V sensitivity needs a precision amplifier.
What comes after Signal conditioning?
The next topic is "Actuators", which builds directly on this one.
How difficult is Signal conditioning?
It is classed as Advanced in Electronics & Embedded (topic 82 of 104). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Electronics & Embedded.