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ONET1191P - Questions on data sheet

Raphael Mosig
Prodigy 140 points
Other Parts Discussed in Thread: ONET1191P, ONET8501PB, ONET1151P

Hi,

currently I'm evaluating limiting amplifiers for 10G optical communications. So I found the limiting amplifier ONET1191P. After reading the data sheet, I've got some questions.

- The frequency response in Fig. 3 shows a peak at ~5GHz. What is the reason for this peak? Is it maybe to compensate of the lowpass behavior of a preceding TIA?

- The differential input return gain shows a dip at ~4GHz. What is the reason for that?

- Does the LOS assert/deassert voltage in figure 10 refers to the input voltage or the output voltage? If it refers to the input voltage, why is it not possible to put the LOS threshold to a meaningful value such as 10 mVpp (the input voltage where the outputs are typically limited)?

Thanks,

Raphael

  • 0
    TI__Expert 8915 points
    Hello Raphael.

    1. There is some peaking in the SDD21 response to compensate for the TIA and for better stressed receiver sensitivity.
    2. The dip in the SDD11 response is most likely due to the measurement setup. Some averaging and or smoothing should have been used.
    3. The LOS was designed to be used with a high transimpedance TIA. Also, there will be part to part variation in the LOS assert voltage for a given resistor value. For this reason, for applications that require LOS, we recommend the ONET8501PB or ONET1151P. On these parts the LOS assert level can be adjusted through the I2C interface.

    Regards,
    Alex.