Hello,

In this configuration:

I see this spectrum:

This measure was made on the PicoZed SDR 2x2 SOM. There was no signal at the input.

Why is there more noise around -Fs/2 and +Fs/2?

Best regards,

Vincent

Hello,

In this configuration:

I see this spectrum:

This measure was made on the PicoZed SDR 2x2 SOM. There was no signal at the input.

Why is there more noise around -Fs/2 and +Fs/2?

Best regards,

Vincent

More noise around fs/2 is due to sigma delta ADC noise shaping, When RF gain is very small, RF signal chain noise floor is dominated by the ADC Nosie floor, if the Over Sampling Ratio is big enough, (HB1/2/3 enable), It makes the K >=8, so the inband Nosie floor ( DC~fs/2 ) [fs=output DataRate] is flat. if K=1, the noise floor is the standard sigma-delta noise floor as observed.

More noise around fs/2 is due to sigma delta ADC noise shaping, When RF gain is very small, RF signal chain noise floor is dominated by the ADC Nosie floor, if the Over Sampling Ratio is big enough, (HB1/2/3 enable), It makes the K >=8, so the inband Nosie floor ( DC~fs/2 ) [fs=output DataRate] is flat. if K=1, the noise floor is the standard sigma-delta noise floor as observed.