Hi Sir,
Hope I am posting at the right place.
My transmitter system block diagram is as below. I need to transmit a bipolar pulse at maximum 200Vpp/50MHz, but for now I cannot achieve acceptable output waveform at the load side(Vout), see below :
output waveform :
As you can see, waveform at Vout is highly distorted, frequency peak at Vout is only about 15MHz, guess I need to do impedance matching on the load side.
However, for a transmitter I believe it is meaningless to use a network analyzer to measure its output impedance while it is not active. Also, it is not possible to measure its output impedance when transmitting pulses due to network analyzer is not able to sustain 200Vpp high voltage. So I need some other way to find out its output impedance.
In RF field as I know, a "load-pull" test is performed to find out the output impedance of a PA (for example : https://www.microwaves101.com/encyclopedias/load-pull-for-power-devices), though the test equipment is expensive and I do not have access to this kind of equipment.
I tried the simplest matching topologies like shunting an inductor or capacitor to ground, adding a series inductor or capacitor with the load, but none of them gave me a better waveform on Vout.
So, is there a feasible way to measure the output impedance of my transmitter ? Or is there a feasible way to do impedance on the output side ?
Thanks in advance !
Hope I am posting at the right place.
My transmitter system block diagram is as below. I need to transmit a bipolar pulse at maximum 200Vpp/50MHz, but for now I cannot achieve acceptable output waveform at the load side(Vout), see below :
output waveform :
- cyan / orange : time and frequency domain at Vtx
- green / pink : time and frequency domain at Vout
As you can see, waveform at Vout is highly distorted, frequency peak at Vout is only about 15MHz, guess I need to do impedance matching on the load side.
However, for a transmitter I believe it is meaningless to use a network analyzer to measure its output impedance while it is not active. Also, it is not possible to measure its output impedance when transmitting pulses due to network analyzer is not able to sustain 200Vpp high voltage. So I need some other way to find out its output impedance.
In RF field as I know, a "load-pull" test is performed to find out the output impedance of a PA (for example : https://www.microwaves101.com/encyclopedias/load-pull-for-power-devices), though the test equipment is expensive and I do not have access to this kind of equipment.
I tried the simplest matching topologies like shunting an inductor or capacitor to ground, adding a series inductor or capacitor with the load, but none of them gave me a better waveform on Vout.
So, is there a feasible way to measure the output impedance of my transmitter ? Or is there a feasible way to do impedance on the output side ?
Thanks in advance !
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