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ADL5513 with Vdd=3.3V and Tadj

Hi all,

We will like to use the ADL5513 logarithmic detector with a 3.3V supply voltage, in the frequency range between 2.6 and 3GHz.

According to Figure 21 of the datasheet, it seems to behave the same with variations on the power supply voltage, at least in 1900MHz.

In Figure 10 of the datasheet, the measurement conditions are Vdd=5V and Vtadj=0.83V. To my understanding of the text under the tittle "Device calibration", this value of Vtadj is optimized for 85°C, is this correct?

To optimize operation at 25°C, the pin Vtadj should be let open? (we are not using the disable feature).

Is Vtadj dependant of the supply voltage?

Best Regards,

Santiago Calvo

  • Greetings Santiago,

    Figure 21 caption is wrong. It reads 1900 MHz, it should be 100 MHz. We are working to correct this known datasheet error ASAP. 

    The Table 4 VTADJ recommendations are for best (lowest) temperature drift, after room temperature calibration. This includes both hot and cold excursions. For 2.6GHz operation, the recommended voltage is 0.83V as stated. If VTADJ pin is left open, it floats to approx. 0.9V, so error is not too bad if the pin is left open. Note, the calibration should be performed AFTER VTADJ is set as desired, not before. 

    I'm not aware of any VTADJ dependencies on VPOS supply voltage.   -Bruce H. 

  • Hello Bruce, thank you for your reply

    Got it about the VTADJ voltage, nice explanation thank you.

    About the dynamic range variation with the supply voltage: Do you have some information on minimum and maximum input level, for a frequency closer to 2.6-3GHz (with know error, like +/-1dB for example)?

    The datasheet specifies this values on -67 and +7 dBm with +/-1dB error, at 2600MHz and Vs=5V

  • Hello Santiago,

    I found data for 1.9GHz showing 2.7V and 5.5V. Just like the 100MHz response of Figure 21, there's not much difference in response up at 1.9GHz with respect to VPOS:

    Kindly remember that these test results are typical. Actual detector response can be different. For high accuracy, individual calibration of slope and intercept is recommended.   -Bruce H.