Programmable attenuator

For this part of the project, we will be using the Mini-Circuits ZX76-15R5-PP+ programmable attenuator. In the following image, you will notice that the attenuator has SMA input and output. That is the other reason I chose an SMA connector for the oscillator. No adapter required!

Mini-Circuits attenuator (copyright Mini-Circuits)

The internal construction of the attenuator is actually quite simple. It's a bank of switches that can be opened or closed to remove or add attenuation, respectively. These switches are controlled by 3 V digital logic.

Attenuator internal schematic (copyright Mini-Circuits)

The fact that the device uses 3 V logic makes it easy to interface to our BeagleBone.