About the mixer in ADF5904

Regarding the question about ADF5904, I mainly focus on the relationship between the frequencies of the LO and RF ends. I hope to use the 24Ghz LO input, and the RF end accepts 24Ghz unmodulated radar signals. The main problem is that if the Doppler benefit is calculated, the RF end frequency may be lower than the LO end when redshift occurs. Regarding this, I did not find relevant information in the manual. Google told me that Mixer can be classified as High-side and low-side  Some Mixers support the above two modes at the same time. I want to know two things. 1.  is the type of Mixer built into ADF5904. 2. It is my personal doubt. When the RF frequency is lower than the LO, what is the output behavior of the Mixer; is the output phase changed or not?

  • Hi,

    Yes for mixers in a receiver in a general sense, low side injection means your LO frequency is lower than your RF signal. 


    However the ADF5904 was designed to be used in an FMCW setup. For example let's say the ADF5901 is used as the Tx. It will also be supplying the LO for the ADF5904 which will be at the same frequency as the Tx signal at each moment in time, which is then compared with the Rx signal to get the baseband signal in a single stage down-conversion. So there’s no IF frequency or high/low side injection. This is called a direct conversion or homodyne receiver, there should be some information available online about direct conversion receivers.

    Regards,

    Alex