High EVM in 80 MHZ BW signals of WiFi

[noori.re]

Hello Every one,

I have a wifi enabled chip. The module has been designed to use this chip for wifi and BT.
I did EVM measurement for WiFi. All bands&bws are ok.
The 6G band shows high EVM in 80 BW signals.
It is also independant of power. so it is not related to PA saturation.
Do you know what would be the next suspecious part insdie chip or even outside?
which part should I investigate?
Thanks

 

[aliarifat794]

Hello Every one,

I have a wifi enabled chip. The module has been designed to use this chip for wifi and BT.
I did EVM measurement for WiFi. All bands&bws are ok.
The 6G band shows high EVM in 80 BW signals.
It is also independant of power. so it is not related to PA saturation.
Do you know what would be the next suspecious part insdie chip or even outside?
which part should I investigate?
Thanks

Check all the antennas, filters, amplifiers, mixers, and oscillators. A malfunctioning or poorly calibrated component can cause higher EVM.

 

[D.A.(Tony)Stewart]

Some common types of EVM corruption are:

• I/Q gain and phase mismatch: gain mismatch originates from the two baseband modulation input signals (I and Q) having an amplitude difference at the upconverter. Phase (or Quadrature) mismatch occurs when the two modulated baseband signals are not 100% in quadrature (90°) when being up converted by the upconverter.
• Symbol clock error: originating at the encoder, the symbol clock controls the frequency and timing of the transmission of the individual symbols
• Phase noise: originating at the LO (RF or IF)
• PA compression and non-linearity: originating in the power amplifier being operated in its compression region or showing non-linearity

ref

 

[vfone]

I've seen test instruments that cannot handle well 80MHz BW at 6GHz, even they say they do.
Check with a released chipset that the instrument is working fine.

 

[noori.re]

I've seen test instruments that cannot handle well 80MHz BW at 6GHz, even they say they do.
Check with a released chipset that the instrument is working fine.

It is teste with two insturment from different manufacturer. The result is almost the same.

--- Updated May 28, 2024 ---

Check all the antennas, filters, amplifiers, mixers, and oscillators. A malfunctioning or poorly calibrated component can cause higher EVM.

good idea. I may rplace everythins in series with 0 ohm resistor/capacitors and measure again.