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VARIABLE PHASE SHIFTER (Open circuit)

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mistyme

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Hello,
My goal is to have a circuit that is broadband OPEN, with a variable phase angle from say 40 degrees to -40 degrees.
How will you do this with inductor and capacitor?
 

A single pole LC in high-pass (or low-pass) configuration can give up to 90-deg of phase shift. For more phase shift need to add more poles.
Keep in mind that cut-off frequencies of the high-pass network must be outside of the phase shift band for this scheme to work.
At higher frequencies the phase shift of high-pass (or low-pass) networks gets a nearly flat response.
 
A single capacitor can generate both phase leading and lagging, in case you would prefer to do without a coil.

The concept is shown in the schematic below. The oscilloscope traces show:

1) AC source

2) volt level across 1 ohm resistor (Notice current leading.)

3) volt level through resistor at right (Notice current lagging.)

 
vfone said:
A single pole LC in high-pass (or low-pass) configuration can give up to 90-deg of phase shift. For more phase shift need to add more poles.
Keep in mind that cut-off frequencies of the high-pass network must be outside of the phase shift band for this scheme to work.
At higher frequencies the phase shift of high-pass (or low-pass) networks gets a nearly flat response.
Click to expand...

How would you do it for a broadband circuit (1GHz to 1.4GHz) terminated as OPEN and can vary the phase from 50 to -50 degrees as shown below;

quasi open circuit.jpg
 

The broadband "open" property can be only achieved by avoiding connecting transmission lines. Don't know if this really an option?
 

FvM said:
The broadband "open" property can be only achieved by avoiding connecting transmission lines. Don't know if this really an option?
Click to expand...

The broadband open circuit can be a reversed-bias PIN diode, right or maybe you have other recommendations on steering a phase shift from -40 to 40 degrees
 

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