How to Measure Gain on an Oscilloscope: A Step-by-Step Guide
Oscilloscopes are powerful tools that enable engineers to monitor voltage fluctuations in electrical signals. They’re also one of the most important tools in an engineer’s toolkit and a useful device for measuring gain.
In this blog post, we will discuss how oscilloscopes measure gain as well as tips on how you can use your oscilloscope to measure gain.
If you would like to learn more about oscilloscopes and their uses, read our blog post about signal analyzers vs oscilloscopes first.
What is Gain?
Gain is a measure of how much an amplifier boosts the amplitude of a signal. It is often expressed as a ratio of input-to-output voltage or current, and is sometimes used as a synonym for “amplification”.
For example, if an amplifier’s output voltage is 1 V whereas its input voltage is 0.5 V, the gain of the amplifier is 2 (1 V / 0.5 V). This amplifier has a gain of two because it increased the voltage by a factor of two. Therefore, gain is essentially how much the signal is amplified.
Gain is important to understand in the field of electronics because it determines how much an amplifier distorts an input signal. For example, if you have a signal that is 0.5 V and you send it through an amplifier with a gain of 2, the output signal will be 0.5 V × 2 = 1 V, which is an ideal output.
But let’s say you use a signal that is 1 V. Then the output signal will be 1 V × 2 = 2 V. When a signal is amplified too much, it can cause problems like clipping and noise.
How do Oscilloscopes Measure Gain?
Before we discuss how to measure gain with an oscilloscope, it is important to understand how an oscilloscope measures gain. Oscilloscopes can be used to measure gain in two ways – manually and automatically.
Manual Gain Measurement: In manual gain measurement, you will set the gain (or amplification) of the amplifier manually, and then use the oscilloscope to measure the voltage drop across an input capacitor. Manual gain measurement can be useful in certain situations, but it is not recommended for general use due to the inaccuracies of the measurement.
Manual gain measurement is a quick way to measure gain, and it can be helpful when making quick measurements between different signals. Manual gain measurement is not recommended for routine use due to inaccuracies in the measurement.
Automatic Gain Measurement: Automatic gain measurement is a more accurate way of measuring gain. It works by sending a signal of known voltage through the amplifier and measuring the output voltage with the oscilloscope.
It is important to note that automatic gain measurement is not instantaneous – it takes a few milliseconds. This means that if you want to measure gain, you will have to run the signal for a few ms and then measure the output voltage with the oscilloscope.
Automatic gain measurement is an accurate way to measure gain, and it is recommended for routine use.
Tips on how to Measure Gain with an Oscilloscope
– Use a clean signal with no noise – It is important to use a clean signal when measuring gain with an oscilloscope.
If the signal has too much noise, then the oscilloscope might not be able to accurately measure the gain of the amplifier. If you are having trouble getting a clean signal, you can use a signal source to generate a clean signal or you can try reducing the gain of the amplifier to get rid of the noise.
– Set the oscilloscope to the correct scale
The scale of the oscilloscope will affect the measurement of gain, so it is important to set the scale correctly. If you are measuring AC voltage, then the oscilloscope should be set to AC volts. If you are measuring DC voltage, then the oscilloscope should be set to DC volts. Also, make sure to set the correct range on the oscilloscope. If you are measuring voltage between 0 and 10 V, then you should set the scale to 10 V.
– Use the right type of amplifier – Different types of amplifiers are designed for different applications. Therefore, it is important to use the right type of amplifier for the application that you are measuring gain for. If you are measuring gain for a low-level application, you will want to use a low-level amplifier. If you are measuring gain for a high-level application, then you will want to use a high-level amplifier.
Limitations of Oscilloscope-Based Measurement of Gain
Even though oscilloscopes are powerful tools, they do have a few limitations when it comes to measuring gain.
– Manual gain measurement is inaccurate – Manual gain measurement is an inaccurate way of measuring gain with an oscilloscope. Therefore, it is recommended that you use automatic gain measurement when measuring gain with an oscilloscope.
– Automatic gain measurement takes time – Automatic gain measurement is an accurate way to measure gain, but it takes time to perform. Therefore, if you want to measure gain quickly, then oscilloscopes might not be your best option.
– Oscilloscope bandwidth is limited – The bandwidth of an oscilloscope is limited, which means it might not be able to accurately measure high-frequency signals. Therefore, you should use a low-frequency signal (such as something between 50 Hz and 500 Hz) when measuring gain with an oscilloscope.
– The oscilloscope must be set up properly – It is important to set up the oscilloscope properly when measuring gain with it. If you are measuring gain for an AC signal, then you should use an AC coupling capacitor. If you are measuring DC gain, then you should use a DC coupling capacitor. It is also important to set the trigger type and level, the vertical sensitivity, the horizontal sensitivity, and the time base.
Gain is a useful measurement to know when dealing with any type of amplifier. Oscilloscopes can be used to measure gain, but they do have a few limitations. When measuring gain with an oscilloscope, it is important to use a clean signal, set the scale correctly, use the right type of amplifier, and set up the oscilloscope properly.