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tx analog filter bandwidth setting

Question asked by manideep on Feb 14, 2017
Latest reply on Feb 15, 2017 by gverma

Hi ,

 

we have  different bandwidth requirements of 2.4MHz, 9.6 MHz,22.5 MHz and 32.5MHz.

we  did different  TX RF bandwidth settings i.e

desired  RFBW                           TX RFBW setting

2.4 MHz                                               8MHz

9.6MHz                                                20MHz

22.5 MHz                                             40MHz

            we observed  EVM  of AD9364 transmitter  with this BW settings in VSA . Below  this RFBW setting  the EVM  is going to worse and  EVM  of 22.5MHz is  much worse  even for the TX RFBW setting is  40MHz.

As per reference manual, the calculations of filter cutoff frequency are,

 RF BW  =2* BBBW

f cutoff = BBBW * 1.6(channel_factor)

  why we need to set  RFBW more than desired BW requirement?.

Are we doing  any mistakes in BW setting?  does tx work for the bandwidth of 32.5 MHz?  please help us on this.

    

why  RX_RF bandwidth is 56 MHz and TX_RF bandwidth only 40MHz?

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