iq balance

The IQ imbalance (amplitude and phase) has a negative effect in the EVM output.
Theoretically there is no difference of the IQ imbalance requirement for different output frequency but depends by the transciever you've use. So, find the answer in the manufacturer datasheet. Allways will be different.

I think that the question is not really clear.
First, you are talking about TX or RX?
Are you designing a tranceiver?
As a general info, I can say that 'g' has more stringent requirements than 'b', bacuase modulation is different.
For RX, the spec depends on your baseband processor. Usually a correction is done in Baseband and today's systems are able to correct +/- 5 deg and +/- 2.5 dB of imbalance.
IEEE papers deals a lot with this issue.
I hope it will help.
Mazz

Thanks a lot, I can't get the detailed 11b datasheet from the chip vendors to do
a comparison. I just want to get a simple idea about the I Q requirement.
May I get a relation between I Q requirement and SNR? Or, Can I say if the
SNR requirement is higher, the IQ requirement also needs to be higher?

Good numbers for IQ imbalance at the receiver output are: a 0.2 dB amplitude imbalance and 1-deg. phase imbalance, resulting in a rejection of approximately 35dB. Rejections starting with 25dB (or better) could be corrected by the baseband processor.
Receive IQ imbalance is affecting the EVM and there is a correlation between EVM and SNR. Depending by the type of modulation the EVM is essentially equivalent to SNR.

Can we have a rough estimation that if the SNR requirement is 10dB and then the rejection requirement needn't to be higher than 20dB? Because 10dB margin over SNR
is enough not to worsen the overall Signal to Noise plus interference ratio.
Can we?