TRF37C75: Requirement of DC bias

Hello Nishanth,

    This is considered to be in the category of a "Class A amplifier" which utilize a standard DC bias configuration like for example: the Darlington gain block amplifier. This sets the bias of the internal transistor. In this case, a Darlington transistor is used which contains two transistors, but acts like a single transistor which has the advantage for high current gain and high input impedance. Having the RF choke inductor to minimize gain and power loss external to the device assists in keeping these devices smaller, having improved q-factor of the RF choke inductor versus an on-die inductor, and having the ability to choose the inductor value that is optimized for the operating frequency band of the application. Internally, there is active biasing occurring; however, this is for adjusting for varying temperatures and voltage ranges.

Thank you,
Sima

Can you explain the schematic which would make things more clearer? 

Thanks and Regards,

Nishanth A B

Hello Nishanth,

    The biasing of the internal transistor is done externally at the output through the use of the voltage source, series resistor, and RF choke for the reasons stated in my previous post. If you need more information with detailed equation/schematic analysis, I can provide that source offline.

Thank you,

Sima