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ad9371 ORX noise raised at frequency edges

Category: Hardware
Product Number: ad9371

Settings:

ad9371 orx IQrate 245.76MHz, bandwidth 200MHz, 

Using the following Orx filter config generated by ad9371 filter wizard 

<obs>
<adcDiv=1>
<rxFirDecimation=1>
<rxDec5Decimation=5>
<enHighRejDec5=1>
<rhb1Decimation=1>
<iqRate_kHz=245760>
<rfBandwidth_Hz=200000000>
<rxBbf3dBCorner_kHz=100000>

<filter FIR gain=6 num=24>
-289
81
-23
-86
229
-354
397
-233
-657
1699
-4172
23010
-4172
1699
-657
-233
397
-354
229
-86
-23
81
-289
0
</filter>

But the received orx signal has raised noise at frequency edge.

if i turn off the signal, the noise looks not flat,check the red curve in following figure.

I try some dec5 filter coefs, no big change. 

thanks 

Parents
  • Hi  ,

    We have also observed same thing in our design. Tx and ORx at 245.76MSPS. Would like to know if your Tx output is clean or are you observing any spurious at offset of 122.88MHz or 245.76MHz from LO. If possible share the spectrum snapshot with 1GHz span. How does the ORX plot look if sine wave is given as input?

    Thanks

Reply
  • Hi  ,

    We have also observed same thing in our design. Tx and ORx at 245.76MSPS. Would like to know if your Tx output is clean or are you observing any spurious at offset of 122.88MHz or 245.76MHz from LO. If possible share the spectrum snapshot with 1GHz span. How does the ORX plot look if sine wave is given as input?

    Thanks

Children