VARIABLE PHASE SHIFTER (Open circuit)
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 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