SIGLENT Help Center | Frequency Response Analysis Using Bode Plot on Siglent Oscilloscopes

Frequency Response Analysis Using Bode Plot on Siglent Oscilloscopes

Jim Wilson

Last Update 20 hours ago

A Bode plot function for frequency response analysis is built-in to nearly all of our current oscilloscopes. Simply couple the oscilloscope with a Siglent Function/Arbitrary Waveform Generator and choose the Bode feature from menu options on the oscilloscope to start.

The Bode Configure screen lets you set the parameters of the frequency sweep. You can also select automated measurements to be displayed at the bottom of the plot.

These meaurements include, upper cutoff frequency, lower cutoff frequency, bandwidth, gain margin, and phase margin.

When you start the measurement, the oscilloscope will control the waveform generator to output a sine wave at the amplitude, offset, and frequency range that you specify on the configuration screen. The scope will measure and display amplitude and phase while controlling the wave form generator to increase frequency.

The Bode plot can be set to repeat continuously or stop after a single sweep.

Bode works with each of the function generators in our current lineup with few exceptions. I recommend our SDG1000X Plus series generators or higher. For an application that requires output isolation, you may want to use an isolation transformer or choose the SAG1021i. SDG series waveform generator outputs are not isolated.

Some of our oscilloscopes such as the SDS2000X Plus and the SDS2000X HD have a built in AWG. So, you can do frequency response analysis without an external generator, but you would have to eventually purchase a license to activate the AWG option when the trial option runs out. The built-in AWG’s of these oscilloscopes are similar in performance to the SAG102i, but they are not isolated.

Follow the link below for a table that lists the oscilloscopes that have waveform generators built-in and those that require an external waveform generator:

https://siglent.tawk.help/article/oscilloscopes-with-built-in-function-generator-or-external-sag1021i-control
Oscilloscopes With Built-in AWG

Using our SDG series generators, choose USB or LAN to make the connection from the oscilloscope to the waveform generator. If using the SAG1021i, connect the SAG1021i module to the USB host port on the oscilloscope. If the oscilloscope has an optional built-in AWG (must be activated) use the AWG/Wave Gen output on the oscilloscope.

Instructions for setting up Bode to sweep the function generator and plot frequency and phase on the scope are provided in each of the oscilloscope manuals. Here is a link that presents an example using a SDS800X HD series oscilloscope to make the measurement.

Bode Example

We offer oscilloscopes for any budget that include Bode analysis, but the Bode option is not available on oscillscope models SDS1052DL+, SDS1000CML+ series, and SDS1202X-E).

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