I recently purchased the ADRF5020 RF Switch (ADRF5020BCCZN) on Evaluation Board (ADRF5020-EVALZ) through Mouser Electronics which arrived in Perth, Australia on the 16th of August.
Through device characterisation and functionality testing, it was found both RF1 and RF2 ports exhibited strange behaviour. During tests, we ensured care was taken by adhering to device specs and following the power up sequence from the datasheet. GThe electrical parameter values and power up sequence we used are as follows;
- VDD set to 3.3 V DC from power supply.
- VSS set to -2.5 V DC from power supply.
- EN and CTRL set to 3.3 V Pulse from digital signal generator.
- RF signal applied to RFC port.
Here is an image of the setup
Figure 1: Test Setup
And a close up of the connections to the switch
Figure 2: Switch Electrical Connections
There are two issues we have observed. The first is DC biasing at both output ports. The RF signal is biased negatively from RF1 and positively from RF2. The two snap shots below were taken with our oscilloscope and highlight this behaviour. For each image, a 2.5 GHz signal is applied to RFC and the pulse generator is set to apply a 16 ns, 3.3 V pulse to CTRL on the switch. The oscilloscope is connected to RF1 for the first image, and RF2 for the second, and is terminated at 50 ohms.
Figure 3: RF1 Output
Figure 4. RF2 Output
The second issue occurs when the voltage to CTRL is set to low. A low impedance path is created between RFC and the port being measured, and the signal at RFC appears at the RF1/RF2, which decays after about 10 to 20 seconds. In this case there is no DC biasing of the RF signal.
Tests were performed on our own equipment to ensure the behaviour was not due to something other than the switch.
Could I please be advised on whether we are not operating the device correctly? If the switch is suspected to be damaged, what are the next steps we should take? Is it possible to send a replacement switch? I am happy to send through any other information or ship the switch itself for an external evaluation. I’ve attached the data sheet and images of our test setup and switch connection.
[edited by: Aaron_The_Engineer at 7:03 AM (GMT -4) on 7 Sep 2021]