Self-oscillation of HMC434E

The customer uses HMC434E.

Does HMC434E have the self-oscillation?

Even if he does not input the signal into HMC434E, it outputs a signal from OUT(pin#6) by self-oscillation.

The frequency is 500 to 570MHz at OUT-pin.

Please tell me the frequency range of self-oscillation of HMC434E.

<Condition of Measurement>

- Using HMC-EVB of HMC434

- Input Vcc=3V

- Input Signal : No Signal

- Output : Connected to Spectrum Analyzer

BR, Tomo

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  • 0
    •  Analog Employees 
    on Nov 19, 2014 5:42 PM

    In the absence of an input signal the HMC432, 433 and 434 will self-oscillate. A 3.3kΩ resistor should be placed in a shunt configuration from the input pin (3) to ground to prevent this. This does slightly impact the input sensitivity, so be sure that the input power level is sufficient. Please refer to the attached application note which covers this is detail. The app note promotes the use of a 4kΩ resistor to stabilize this divider but recently it was discovered that to this value needed to be reduced to 3.3kΩ to better address lot to lot variations. The application note is currently in the process of being revised to address this change. The impact to the input sensitivity due to the reduction in resistance is negligible (1-2dB). 

    frequency_divider_operationcompensation_with_no_input_signal.pdf
Reply
  • 0
    •  Analog Employees 
    on Nov 19, 2014 5:42 PM

    In the absence of an input signal the HMC432, 433 and 434 will self-oscillate. A 3.3kΩ resistor should be placed in a shunt configuration from the input pin (3) to ground to prevent this. This does slightly impact the input sensitivity, so be sure that the input power level is sufficient. Please refer to the attached application note which covers this is detail. The app note promotes the use of a 4kΩ resistor to stabilize this divider but recently it was discovered that to this value needed to be reduced to 3.3kΩ to better address lot to lot variations. The application note is currently in the process of being revised to address this change. The impact to the input sensitivity due to the reduction in resistance is negligible (1-2dB). 

    frequency_divider_operationcompensation_with_no_input_signal.pdf
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