PXIe-NI-2532B Card

[ArunMgowda]

Hi,

We are using the the PXIe-NI-2532B Signal Switching Card the card has the bandwidth of 30Mhz , we are not able to switch the pulse of 5Mhz ,10% of duty cycle the switched waveform has more distortion has lost its shape from pulse it shows like a sinewave ,

Kindly suggest in this ,

The testing scenario is For RO we have provided the signal from Pulse Generator and switched to C0  which has the independent setup with the coaxial cables ,

Thanks and Regards:

+91 9591519820

[santo_13 · Accepted solution]

Bandwidth is the frequency at which the signal amplitude reduces to 70.7% or -3dB. Bandwidth is always defined for sine wave as it is the only shape which has a single frequency component (look at FFT of sine wave).

Now, this means, if you feed in a 1V pk sine wave into the switch it'll be attenuated to 0.707V pk

Now, let's get to a square wave, if you know signals and systems, square wave is represented as a infinite sum of odd harmonics of fundamental frequency.

A 5MHz frequency consists of a lot of sine waves of different frequencies and amplitudes added together like 5MHz, 15MHz, 25MHz, 35MHz, 45MHz ....

Higher the frequencies the perfect the square wave is. Now applying your 30MHz bandwidth, any frequency component at and above 30MHz is attenuated, so literally you've only 3 frequency 5, 15, 25 combined to form a square wave which is insufficient and hence they would look like a sine wave.

Hope this clarifies.

[rolfk · Accepted solution]

For a 5 MHz square wave to be passed through a signal transmission line to still resemble a square wave, you will need a bandwidth of at least 100 MHz or more. The higher the bandwidth is the better will your output signal resemble the original square wave. That's fairly basic engineering college knowledge.