My customer has the following requirement "The receiver response to spurious signals, including image response, shall be attenuated not less than 80 dB with respect to the received signal."
The specification for the ADRV9009 is 75db (QEC active within 200MHZ receiver bandwidth) for image rejection. Is it possible to achieve greater image rejection at lower bandwidths? Can we achieve spurious performance at this level?
Let me know,
The QEC levels do not vary much with bandwidth. We cannot guarantee performance across lot more than what is specified in datasheet.
You can use ADRV9009 Rx in Low IF mode, so that image falls out of band and can be filtered.
Please refer to UG-1295, Section GSM Use cases for more details. Where ADRV9009 is configured for 75 MHz low if mode to achieve better dynamic range.
Thank you. One more clarifying question:
Is the image centered around the tuned center frequency and is there a notch at the center frequency (DC at baseband)? If there is a notch, how wide is it?
From User Guide.
The digital dc offset correction effectively creates a narrow-band notch filter around the dc, which can lead to degradation of the subcarriers on or close to dc depending on the subcarrier spacing. If the default dc offset settings are causing this type of degradation, the API provides commands to adjust the filtering behavior near the dc.The mShift parameter controls the frequency corner for the narrowband notch filter. The mShift parameter can be set with theTALISE_setDigDcOffsetMShift() command. Note that larger mShift values correspond to narrower notch filter bandwidtharound the dc. A narrower notch filter corresponds to an increased convergence time for the digital dc offset calibration. The notch filter bandwidth is typically set on the order of 10s of kHz.The Arm processor selects an mShift value depending on the profile sample rate. If this selected mShift value is not desired, call theTALISE_setDigDcOffsetMShift() command before the dc offset initialization calibration occurs to change the mShift value. See the DC Offset API Functions section for more information.
Refer UG-1295 User Guide for more details
Can you give me the direct link to the user guide, I keep getting back links. Thanks. And is it named something else. Customer cannot find also...
user guides are downloaded upon registration from below link. It is part of design file package. Each time you need to register for a download.
Thanks! I found it!