Can AD8306 be used as an AGC amplifier


   I'm a bit confused about AD8306.Can this chip control the output amplitude?Can it be used as an AGC amplifier?


  • 0
    •  Analog Employees 
    on Jun 9, 2018 12:37 PM


    We are looking into this. We will get back to you soon. 



  • 0
    •  Analog Employees 
    on Jun 11, 2018 6:51 PM

    The AD8306 is not a stand alone AGC amplifier. 

    The AD8306 can be used in an analog AGC loop as a power detector, wherein it senses the output power of a VGA and RSSI output controls the VGA's gain pin.  You would have to design the AGC loop according to the specifications of the VGA, most likely scaling the RSSI voltage and possibly inverting the RSSI slope, i.e. make it negative, so that the AGC loop polarity is correct.  Note, inverting the RSSI slope will depend on the VGA's available slope(s).   

  • Hi,

      Thank you very much for receiving your reply.Since my chip of AD is using AD9430 .I hope my chip of AD can work normally. And My frequency range of transmission is 20M~50M. If I want to use AD8306,can you give me a reference on the chip of VGA? Can you provide me with a rough plan,please? I really need your help. Thanks again!

  • Hi,

        I still have a question, if my input range is -62dBm~-1dBm, then zoom in through AD8306, and finally I can enter the AD9430 chip.Is there any problem with such a plan,please?I saw the chip datasheet that the maximum output voltage in LIMTING AMPLIFIER  is 1.25V. Does it mean hat by setting when my input is -1dBm, my output can reach 1.25V(11.94dBm)? 

       I hope to get your reply as soon as possible.Thanks very much!

  • 0
    •  Analog Employees 
    on Jun 13, 2018 7:12 PM

    I need to know your application and specifications before recommending anything: 

    • Are you trying to build an AGC loop? 
    • What frequencies do you need to operate at?

    Note that the limited amplifiers output is a square wave.  What are you attempting to do with the sampled limited output?  Are you trying to detect the phase of the signal?

    The output should be a square-wave over most of the AD8306's input range due to the large amount of gain in the limiting amplifier chain.  Limiter output Vpp is set by the RLIM resistor (see figure 22 in the datasheet).