Explanation of the "isolation" parameter in RF PA

Who can explain me the "isolation" parameter of RF Power amplifier? The unit for this parameter is "dBm".

What is isolated DC-DC and Non isolated DC-DC?

Thanks

Re: parameter in PA

1) I dont know much about isolation parameter of a power amplifier. Probably it may be something related to output - input isolation.

2) DC/Dc Converters can be broadly classified as Non-isolated and isolated dc/dc converters. In non-isolated converter, the input return and output return will be same i.e. input and output are at same ground reference. There will not be any transformer b/w input and output. .

Eg. Buck Converter, Boost Converter, Buck-Boos converter.

In an isolated dc/dc converter the input and output will be referred to different ground points. Hence, in between input and output there will be a transformer isolating the two ground points. The input source, Switching element and the transformer primary winding will be on one side. Transformer Secondary, Rectifiers and Filters on the other side. Hence there wont be any connection b/w input and o/p side other than the magnetic coupling of the transformer.

Eg. Forward/Flyback/Push-Pull converters.

An isolated power supply is desirable for many situations. But the major problem associated with them is - the sensing of output lines - for completing the feedback control loop, because we have to control the duty cycle of the switching element in input side in accordance with changes in voltage at output side which are referring to different ground points.

Usual methods for sensing in such isolated converters are
(i) Optocoupler method (optocoupler is biased to operate in active region which then will give linear output)
(ii) Sense signal is amplitude modulated and given back to the input side through a transformer. There at the secondary it is demodulated and given to the controlling circuit
(iii) Providing a separate sensing winding in the transformer which is not isolated from input

Hope these information will help you

- SUjO

parameter in PA

1)For PA forward isolation, it means when the PA is shutdown (no power supply), the power coupled from input to output. It's used in GSM handset power amplifier module filed.