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LMX2492 - How stepped sawtooth waveform generation

Hiroaki Masumoto
Expert 1210 points
Other Parts Discussed in Thread: LMX2492

Hi, all

We are introduced the LMX2492 to FM-CW radar applications to customers.

I have received questions about the FSK RAMP waveform from customers.

Please refer to the attached PDF file.
LMX2492_stepped_sawtooth_waveform.pdf

Questions

1. Is it possible to generate a stepped sawtooth waveform using the LMX2492?

2. Please tell me the setting examples such as 9.2.4 of the LMX2492’s data sheet on page 30, if it is possible.

Best Regards,
Hiroaki Masumoto

  • 0
    TI__Mastermind 28001 points

    Masa-san,

    The LMX2492 can generate a waveform with up to 8 linear segments.   It can do a stairstep waveform, but each vertical step counts as a ramp.

    The waveform you have would actually require 13 segments, so I do not think it is possible.  Note that the last return can be done with the RAMP_RST bit.

    Regardsa,

    Dean

  • 0 in reply to Dean Banerjee
    TI__Mastermind 28001 points
    Masa-san,

    Although the LMX2492 can not do this in an automatic repeating pattern, there are two ways this could be done:


    1. Manually program each frequency through the programming interface.
    These steps are slow enough that this allows enough programming time.

    2. Use 2 Ramps with the Limiter and Comparator
    a. RAMP0 is a flat ramp which goes to RAMP1
    b. RAMP1 is a very fast ramp (close to vertical) that loops back to RAMP0
    c. Do NOT reset the ramp on RAMP0
    d. The LMX2492 has comparator and frequency limits that will both stop the ramp from going past a pre-set limit and will also output a warning signal to the pin. Although the LMX2492 will not automoatically reset the ramp, you can do this through software.
  • 0 in reply to Dean Banerjee
    Expert 1210 points

    Hi Dean-san

    Thank you for your quick response.
    I understand the contents of the reply.
    I will inform this information to customers.

    Regards,
    Hiroaki Masumoto