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TRF371135 query

Sai Jagini
Expert 1205 points


HI,

The data sheet is missing on the following information: (1) The typical values of IQ imbalance (phase and amplitude) of this chip over the entire frequency range.  (2) The LPF is adjustable with values between 0 to 255. We need to know the LPF type (I guess it is analog. Is it chebyshev?). and the taps of the filter for the widest LPF (Cutoff approx 15MHz by setting a value of 0). We see that there is a peaking in the response and we need to equalize this, hence we need the impulse response of the filter.  (3) The SPI is not very stable. Our Logic Analyser has dumped the three pins and it meets the timing diagram very accurately. Is there anything missing in the timing diagram? We get is to work 80% of the times, some times it will not configure. We have used the clock below 20MHz (tired at 5MHz and 10MHz).

Please help us to get the following information.

  • 0
    TI__Mastermind 18095 points

    (1) The typical values of IQ imbalance (phase and amplitude) of this chip over the entire frequency range. 

    A: The I/Q is not specifically measured.  Image rejection is measured.  Typical performance is 40 dBc regardless of RF frequency.

     (2) The LPF is adjustable with values between 0 to 255. We need to know the LPF type (I guess it is analog. Is it chebyshev?). and the taps of the filter for the widest LPF (Cutoff approx 15MHz by setting a value of 0). We see that there is a peaking in the response and we need to equalize this, hence we need the impulse response of the filter. 

    A: The LPF is an active 8th order Butterworth type filter.

    (3) The SPI is not very stable. Our Logic Analyser has dumped the three pins and it meets the timing diagram very accurately. Is there anything missing in the timing diagram? We get is to work 80% of the times, some times it will not configure. We have used the clock below 20MHz (tired at 5MHz and 10MHz).

    A: I have not seen sensitivity to SPI stability previously.  This could be a USB driver issue.