Teledyne LeCroy Factory Tour Day 1, Post 1

This week I am at the Teledyne LeCroy factory in Chestnut Ridge, NY. Besides enjoying the cold, rainy and dark weather, I’m going to share lots of pictures and videos with you throughout the next days and weeks. If there are any questions you’d like me to ask during interviews or there’s anything in particular you’d like me to cover, let me know!

Here are a few pictures of this morning’s Factory tour:

IMG_6549

IMG_6581

IMG_6636

IMG_6637

IMG_6662

IMG_6759

IMG_6951

IMG_7029

 

Tektronix RSA306 IF Frequency Verification

After posting the teardown video of the Tektronix RSA306 USB 3.0 Spectrum Analyzer on my YouTube channel, someone asked me to verify that the IF sampled by the Linear Technology 14-Bit / 125 Msps ADC is really at 140 MHz. Using the Tektronix MDO4104B-6 and a passive RF probe, I gladly did so.

With a 100 MHz, 0 dBm signal applied to the spectrum analyzers input and the SignalVu-PC settings set to 100 MHz center frequency, 40 MHz span, the signal at the ADC input looked like this:

Spectrum at the LTC2261-14 input with a 100 MHz, 0 dBm signal

Spectrum at the LTC2261-14 input with a 100 MHz, 0 dBm signal

So indeed, 140 MHz is our strongest peak. 20 dBc lower is a 28 MHz peak. Before taking the picture I of course tried a large span to make sure that there aren’t any relevant signals at a lower frequency. So the next test uses a 105 MHz signal still at 0 dBm.

Spectrum at the LTC2261-14 input with a 105 MHz, 0 dBm signal

Spectrum at the LTC2261-14 input with a 105 MHz, 0 dBm signal

So indeed, it seems that the LTC2261-14 samples the 140 MHz IF directly. How you ask? The answer is undersampling. The ADC is actually sampling at 112 Msamples/s. As a result, it sees an alias of the 140 MHz signal at 28 MHz. That’s all the magic happening here.

This probing expedition also yielded some pretty pictures that I would like to share. Enjoy!

Probing around inside the Tektronix RSA306 USB 3.0 Spectrum Analyzer

Probing around inside the Tektronix RSA306 USB 3.0 Spectrum Analyzer

Probing around inside the Tektronix RSA306 USB 3.0 Spectrum Analyzer

Probing around inside the Tektronix RSA306 USB 3.0 Spectrum Analyzer

Probing around inside the Tektronix RSA306 USB 3.0 Spectrum Analyzer

Probing around inside the Tektronix RSA306 USB 3.0 Spectrum Analyzer