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LMG1020: is there any clock reference board or IC which is verified with TIDA-01573?

YoungYun Kim
Intellectual 410 points
Part Number: LMG1020
Other Parts Discussed in Thread: TIDA-01573, ,

To whom it may concern

Cutomer wants to apply below reference to his product for Lidar Module.

http://www.ti.com/lit/ug/tidue52/tidue52.pdf

Before applying the reference, He would like to take TI recommendation for Clock generator.

From the pdf file, TI used external generator equipment. But In order to generate Pulse, Customer should use IC on real developmet product.

Could you please let me know if TI has recommendable  or verfied Clock generator reference board or IC with the above reference board?

Now, Customer is considering 1-ns pulse width.

I appreciate your help in advance.

Best Regards

Mark Kim

  • 0
    TI__Genius 12990 points
    Hi YoungYun,

    TIDA-01573 is the same as the LMG1020EVM-006. Figure 2 of the LMG1020EVM-006 User's Guide highlights the schematic. Here you can find the clock generator or as we call it, the pulse shortener, which consists of U3 AND gate or digital buffer with the R9/C11 low pass filter. The combination of the low pass filter and AND gate can be used as a pulse shortener allowing a regular function generator to achieve 1-2 ns pulses on IN+ pin of LMG1020. Most function generators can only output pulses as low as 10 ns, therefore the ability to create a 1-2 ns pulse can be achieved on the EVM using the AND gate input (J3). The AND gate compares the input (J3) to a RC delayed version and when both inputs are high the output will go high. The input pulse width or falling edge from the function generator can then be fine tuned in order to see the desired pulse width on IN+. When first starting to fine tune the function generator input to see the pulse on IN+, start with 100 ns then reduce the pulse width down by the nanosecond or smaller to make 1-2 ns visible on the IN+ test point. To bypass the pulse shortener populate R3 with a 0-Ω resistor and remove R9 and R10 to disconnect the AND gate input and output respectively.

    does this make sense? let me know if you have any more questions on achieving a 1ns pulse width on the EVM.
    thanks,
  • 0 in reply to Jeffrey Mueller
    Intellectual 410 points
    Hi Jeff
    appreciate your advice. I will check your comment with customer.
    But , I might need your help more.
    From Your commnet and figure 6~8, I assume that Pulse generator ouput around 90ns width(High) pulse in order to achieve 1ns pulse at AND gate output.
    It means that Customer wait another 90ns to achieve anther 1ns. It is my understanding for your comment and figure 6~8.

    But if customer wants to get consistent 1ns pulse like sine wave form ( 1ns high, 1ns low), Is there any recommendable circuit?
    thank you
    Best Regards
    Mark Kim
  • 0 in reply to YoungYun Kim
    TI__Genius 12990 points
    Hi YoungYun,

    I understand that the customer wants a 2ns period with 50% duty cycle (1ns on and 1ns off) which is 500MHz switching frequency.
    This high frequency may not be possible with LMG1020 EVM. You can achieve faster frequency by bypassing the pulse shortener AND gate and by using a RF frequency generator to generate 1ns on-time pulses. You can replace the J3 header with an SMA connector to allow a higher frequency on the EVM however 500MHz is very high and will be limited by the EVM GaN FET and layout parasitics. It may however be more feasible to create a separate board with optimized layout and FET to allow a higher switching frequency than the EVM. Does this help answer your question? Please let me know if you have any more questions.

    thanks,