Solved: LimeSDR Mini VCC1P8 Measures 2.2 V

I have a 10-month-old LimeSDR Mini Version 1.1 that works (almost) perfectly. However, today I happened to measure the voltage on the VCC1P8 terminal (pin 5) of the FPGA EGPIO connector and it measures 2.20 volts (pin 4 is correct at 3.29V). I have checked another LimeSDR Mini (Version 1.2) and it reads 1.80 volts on pin 5.

Am I in danger of blowing up the LMS7002M by continuing to use the device?

What caused me to measure the voltage was the investigation of a temperature-related phase noise problem on a QPSK output signal at 3.4 GHz. Surprisingly, the phase noise decreases as the device heats up. The VCC1P8 does not change though, so it is not the directly causing the change in phase noise. In fact it remains stable at 2.2 volts despite changes in USB supply voltage or temperature.

Grateful for advice on how I should proceed.


Hi @DaveG8GKQ,

It is designed to provide 2.2V instead of 1.8V. Hence it is everything OK here.

Thanks @Zack

So for LimeSDR Mini hardware V1.1 VCC1P8 = 2.2V, but for hardware V1.2 VCC1P8 = 1.8V ?