LDMOS RF Power Amplifier Bias Controller

[snmeciut]

Dear

I want to control of bias of three stage amplifier in L band for control of temprature and stability of amplifier.

I found DS1870 (Maxim) and X9470 (Intersil).

have you any suggestion for this work?

Best Rigards

 

[ajar2dtn]

I think the Maxim part is a good choice for a currently available part.
I am designing it into a 400MHz PA for which the device will control the bias of the driver & final LDMOS devices. For this part you have to provide a separate current sense amplifier and voltage reference. I would have prefered a serial SPI bus to the I2C as I2C requires bidirectional data line and more complicated protocol. Also you may have to add additional circuit to fully bias the LDMOS off as the EPOT only goes between 3v to 5V.
I know Maxim are developing other parts that include more features such as the voltage ref and current sense amplifier for release sometime next year.

Added after 19 minutes:

Another crowd worth looking at is Integration Associates www.integration.com that have a single part that can control 4 LMDOS devices. Part no is IA4910.

 

[jarys]

Is bias control necessarily in amplifier with LDMOS ??
How is the large influence of temperature on parameters in amplifiers with transistors LDMOS ??


thanks for information

 

[ajar2dtn]

This article by Jed Rice might shed some light on your question

Also see his other article at;
**broken link removed**

 

[springf2000]

i think use the D/A to control the bias is enough,no need to use the specificed chip

 

[ajar2dtn]

You may well be right and it certainly would be cheaper.
It think it would depend on how sensitive the required performance criteria are to bias drift.
In my instance I am concerned at mantaining linearity over operating temperature and product life.