Terminators / Impedance Matching

[loonychune]

I am not sure how the use of a terminator with an oscilloscope works.

I have a signal going into the input of an oscilloscope and improved this signal by attaching a terminator to the input of the scope.

The way I understand it is, that the scope has a large impedance, larger than the impedance of the source and so a voltage results which can't be overcome by the signal, so not all of the energy of the signal is absorbed; some is absorbed which results in signal being reflected back and so original signal becomes distorted.

Can you explain if this scope is in fact a 'load' -- if it isn't, then I just have a source with an impedance and an open end (zero impedance?) and all of the signal is going to be reflected: then how is anything going to be detected?

Thanks

(p.s. i wouldn't have thought this is really an homework question)

 

[Valerie Park]

Yes, an oscilloscope is indeed a load. The input of the scope is designed to have a certain impedance that allows it to detect the signal coming from the source. A terminator helps to ensure that the signal coming from the source is not reflected back and lost in the system, by providing a matching impedance at the input of the scope. This ensures that all of the signal energy is absorbed by the scope and can be accurately detected.

 

[sir-pinski]

Terminators and impedance matching are important concepts in electrical engineering, especially when using oscilloscopes. Let me try to explain how they work in simple terms.

First, let's clarify what impedance is. In simple terms, impedance is a measure of how much a circuit resists the flow of electricity. It is similar to resistance, but also takes into account the effects of capacitance and inductance in a circuit. Impedance is measured in Ohms (Ω) and can vary depending on the frequency of the signal.

Now, when you connect a signal source to an oscilloscope, there is a mismatch in impedance between the two. The oscilloscope has a high impedance (usually in the range of 1MΩ), while the signal source may have a lower impedance (for example, 50Ω). This mismatch can cause signal reflections, which can result in distorted and inaccurate measurements on the oscilloscope.

This is where terminators come in. A terminator is a device that matches the impedance of the signal source to the impedance of the oscilloscope. It acts as a load for the signal, absorbing the excess energy and preventing signal reflections. This allows for more accurate and reliable measurements on the oscilloscope.

To answer your question, the oscilloscope is not considered a load in this scenario. It is simply a measuring device. The terminator acts as the load, matching the impedance of the oscilloscope to the impedance of the signal source.

In summary, the use of a terminator with an oscilloscope helps to prevent signal reflections and ensures accurate measurements. It is an important tool in impedance matching and can improve the overall performance of electronic circuits. I hope this helps to clarify the concept for you.