Can I use ADG801to switch DC bias of Gain block?

Hi,

I am designing a RF transmitter/ receiver system. While in receive mode (which is default mode) all the RF devices (amplifiers) of the transmitter chain need to be in off state. They will be switched ON only when in transmit mode.

Generally I use MOSFET & BJT combination to switch the DC supply for RF devices (amplfiiers).

In case of gain amplifier (low RF power devices) I want to use ADG801 or similar device because this gain amplifier needs only 150mA (max) at 5.0V. ADG801 will help me in reducing the BOM as well as occupy less space & easy functioning.

Kindly give your suggestion on this approach.

  • Hi all,

    Kindly reply to my query. I need to complete the circuit design.

    Regards,

    Rajan

  • 0
    •  Analog Employees 
    on Jun 8, 2017 12:19 PM

    Hi Rajan,

    I think you should run this application past our amp group as well for feedback. what amp are you using?  The application here is you want to turn on/off the supply voltage to the amp?  You should also look at our load switch options that are specifically designed for switching in power supplies. 

    Regards.

    Eric.

  • Hi Eric,

    This amplifier is a wideband PHEMT based MMIC amplifier with P1dB of 20dBm (0.1Watt) RF power (minicircuit MNA-6A+). Yes I want to turn on/off the supply voltage of amplifier.

    Thanks for suggesting "Load switch" devices. It looks like load switch will be more suitable for this requirement as compared to Analog switch.

    Thanks & regards,

    Rajan

  • Hi Eric

    I checked "load switch" devices. These devices are good covering voltage as well as current requirements.

    But the turn-on / turn-off times are very high.

    I need turn -on time less than 5us where as Turn-off time can be 100us (approx).

    Considering Timing requirements can we select ADG801 for my application.

    Regards,

    Rajan

  • 0
    •  Analog Employees 
    on Jun 12, 2017 8:08 AM

    Hi Rajan,

    Looking at the MNA-6A+ datasheet, the DC biasing conditions look different to what you are posing, they recommend a very specific setup using a 33ohms resistor on pin 8 and a 1000pF shunt cap connected to pin 7 and 8 which are shorted to the DC supply.  Your schematic looks different, you are biasing up on the output? Will this affect RF matching?  Have you been in contact with Minicircuits for support on using that product in the configuration you have?  I can't really comment on it.   

    Note, we have a range of similar amplifiers that are supported.  The HMC375LP3 comes to mind, you can ask questions in the RF section in EZ on it.

    Regards,

    Eric.