input impedence for matching design

[Barack]

only schematic drawing, how can I know exact input impedence of the matching circuit.

 

[kspalla]

you need to check the data sheet , estimate the bias etc.

 

[Barack]

thanks for your reply, but can you tell more detail, drowing like attached, how to estimate the input impedence of the matching circuit according to datesheet. (IRFR110)

 

[BigBoss]

thanks for your reply, but can you tell more detail, drowing like attached, how to estimate the input impedence of the matching circuit according to datesheet. (IRFR110)

If you simulate your circuit, you can see quickly than calculate..

 

[Barack]

thanks kspalla and bigboss. I will try.

 

[kspalla]

the circuit is looking like DC to DC converter.
the transistor is switched by the control input and impedance will vary.
You can find on and off impedance from the data sheet.

 

[Barack]

yes, I can check the on and off impedence from the datesheet, but only impedance no reactance. how can I do it.

 

[kspalla]

it will have resistance only, no reactance for switch.

 

[Barack]

this circuit is part of transmitter. now I want to design a new matching circuit. but I really can not understanding why only have resistance and without reactance. what is the input impedence now I can use for simulate?

 

[Barack]

but the antenna should have reactance, for source, should also have conjugate impedence, then can matching. means, C4 and L7 I have to consider if do simulate this circuit?

 

[kspalla]

What kind of transmitter it is? is it ASK?

 

[Barack]

Is for RF power amplifier circuit. center frequence at 8.2MHz. with 1M bandwidth.