HMC681ALP5E

Hi, please advise why is the Relative Gain is expressed in negative dB in the

HMC681ALP5E

data sheet truth table: 

Usually negative dB mean attenuation, however, the device is supposed to be a 45db Amplifier. 

Thank you! 

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  • 0
    •  Analog Employees 
    on Feb 9, 2017 6:05 PM

    Hi artemen,

    There is an important distinction to be made between the HMC681A part and the HMC681A EVB. The part itself allows access to the individual RF inputs and outputs for both amplifiers (let's call them Amp1 and Amp2) and for the variable attenuator (let's call it ATTEN). For example, if you designed your PCB to do so, you could use just Amp1 followed by ATTEN. Also, if you designed your PCB to do so, you could use just ATTEN followed by Amp2. Or string them up differently. The four die within the package effectively constitute three independent blocks: Block1=Amp1, Block2=(Serial controller + variable attenuator), Block3=Amp2. On your own PCB you could configure them in any way you desire, but on our EVB the only available configuration is RFIN>Amp1>ATTEN>Amp2>RFOUT.

    Regarding the maximum signal amplitude applied to the input of either of the two amplifiers, see the bright yellow highlighted sections of the data sheet's AMR table below. You will also want to be aware of the linearity (e.g. P1dB & IP3) associated with each gain setting. For that information see the data sheet plots, which contain data for operation using the data sheet's Application Circuit.

    Regards,

    SMcBride

Reply
  • 0
    •  Analog Employees 
    on Feb 9, 2017 6:05 PM

    Hi artemen,

    There is an important distinction to be made between the HMC681A part and the HMC681A EVB. The part itself allows access to the individual RF inputs and outputs for both amplifiers (let's call them Amp1 and Amp2) and for the variable attenuator (let's call it ATTEN). For example, if you designed your PCB to do so, you could use just Amp1 followed by ATTEN. Also, if you designed your PCB to do so, you could use just ATTEN followed by Amp2. Or string them up differently. The four die within the package effectively constitute three independent blocks: Block1=Amp1, Block2=(Serial controller + variable attenuator), Block3=Amp2. On your own PCB you could configure them in any way you desire, but on our EVB the only available configuration is RFIN>Amp1>ATTEN>Amp2>RFOUT.

    Regarding the maximum signal amplitude applied to the input of either of the two amplifiers, see the bright yellow highlighted sections of the data sheet's AMR table below. You will also want to be aware of the linearity (e.g. P1dB & IP3) associated with each gain setting. For that information see the data sheet plots, which contain data for operation using the data sheet's Application Circuit.

    Regards,

    SMcBride

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