• TI Thinks Resolved

IWR6843: smallest chirp time

Intellectual 2210 points

Replies: 1

Views: 28

Part Number: IWR6843

Dear e2e support,

My customer have these generic questions about our mmWave limitations:

-          What is the smallest chirp time programmable, with a “sawtooth chirp” ?

-          What is the smallest chirp time programmable for a quasi-triangular chirp (also called “slow FMCW”, if I'm right), up-ramp time, idle time, down-ramp time?

-          They are looking for a chirp time of a few 10µs. If not possible with the standard software interface, would it be possible by some other means of access?


  • Hi, there:

    You can find some of this information at: www.ti.com/.../swra553a.pdf

    The smallest chirp time is controlled by:

    1) minimum idle time (=2us, if RF bandwidth is less than 1GHz)

    2) minimum numADCsample (64) / maximum ADC sample Time (12.5MHz) = 5.12us

    3) minimum ADC start time (= 4us, if use a slope less than 50MHz/us and larger ADC sampling rate)

    4) minimum Excess ramping time = 1us

    Which adds up to about 12.12us. 

    For the quasi-triangular chirp, you need 1 chirp to program ramp up and 1 chirp to program ramp down, total 2 chirp.  So the minimum duration will be 2 * 12.12us.