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.)

 

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;

 

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

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

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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