ADS52J90 optional Digital I-Q Demodulator

John,

We are looking into this.

Regards,

Jim

John,

Currently we do not plan to support this optional demod feature mentioned in the datasheet without a business case.
Can you provide more information about your application?
Any particular reason why the ADS52J90 device was chosen for your application?

We have a battery powered application that requires an octal high speed ADC. We want to capture a relatively narrowband signal in the 9 to 11 MHz region. Our earlier generation  proof of concept system ran from 13 to 15 MHz and used a 60 MSPS National Instruments acquisition system that was not easily portable or especially low power. That system computed 64 k point FFT's on the full 60MSPS data rate. We want to replace that unit with something portable that could run all day on a laptop battery. If we can perform digital downconversion, filtering and decimation to significantly reduce our output word rate then we can shorten the FFT length by the decimation ratio.

 Our next development phase will be to buy EVM's for a couple of candidate ADC's and interface them to an FPGA module. I am primarily an analog design engineer, and a subcontractor will be developing FGPA firmware. If we don't use an ADC with filtering and decimation capability, then we have to put more capability (and power) into the FPGA module. 

Parts that I have looked at are the ADS529x series, which has a 24 tap FIR filter and decimate by 2, 4 , or 8 options, and the AFE5809, which appears to have quite a bit more capability in the way of demodulation, filtering and decimation, but also runs quite a bit higher power. We are not doing ultrasound and so would not use many of the AFE5809 features. Also, there is some impact in channel to channel gain matching in the AFE5809 probably due to the Voltage Controlled Attenuator. 

I have also downloaded a datasheet for the AFE5812. At first glance I can't see much difference between the AFE5809 and AFE5812. It appears that there is some assembly required in using the filtering and decimation features of those parts, but apparently you can have a pretty long FIR (16 times m) at the higher decimation ratios for a sharp cutoff filter.

Anyway, the ADSJ90 appeared to be a potentially low power ADC solution so I was curious as what it's "Optional I-Q Demodulator" could do. It seems no one has asked about this feature.

If you could provide some examples of how to use AFE5809 I Q demod and decimation filter that would be helpful.

AFE5809 and AFE5812 have similar features except for channel power and operating temperature range.

Please refer to the TI Design "SONAR Receiver Path Sub-System Reference Design Using the AFE5809" for examples on IQ demod and Decimation filter blocks (www.ti.com/.../tidu702.pdf)