"Power match" Vs "Conjugate match"

[wccheng]

Dear all,

What is the different between "Power Match" and "Conjugate Match"? I just know that conjugate match could cancel out the imaginary part and give out the highest power delivery from source to load. How about the power match? Is power match same as conjugate match?

Thanks

 

[BigBoss]

Power match is quite different than conjugate match and it is used only for Power Amplifiers.It doesn't have an trivial equation but measurement or simulation.
Power match is used to find the optimum impedance as a load for an power amplifier.

 

[flyhigh]

Hi

Conjugate match is taking into account that a device (a transistor) is a two port device and doesn't assume that the signal flow is unilateral. In other words, the input impedance is dependent on what is connected to the output and vice versa.

On the other hand, power match is, as BigBoss explained, only concered with maximum power delivery to the load.

flyhigh

 

[zopeon]

Maximum power transfer theorem states conjugate match is required for maximum power transfer but if you consider it for a active device it has limitations for eg. if your device can source maximum of 1A and has impedance of 100ohms using conjugate match the load voltage would be 50V exceeding the feasible voltage from source. So power match can be seen as a real compromise to the theorem for maximum power.
Its explained better in "RF Power Amplifiers For wireless Communications - Steve Cripps"