Digital phase shifter

Claim 2

A digital phase-shifter circuit capable of providing 360* phase shifts for use in phased array applications, comprising: first and second quadrature hybrid means, each having four terminals; first and second voltage-variable reactance meAns connected respectively to the second and third terminals of said four terminals of said first quadrature hybrid means; third and fourth voltage-variable reactance means connected to the second and third terminals respectively of said second quadrature hybrid means, said voltage-variable reactance means acting as reactive loads on their respective quadrature hybrid means, each of said quadrature hybrid means in combination with their respective voltage-variable-reactance means acting to shift the phase of a input signal by 90* plus the phase shift due to the reactive load on said quadrature hybrid means; and digital-to-analog converter means acting to receive a digital input and convert said digital input into an analog control voltage, said analog control voltage being applied to each of said voltage-variable reactance means and acting to vary the reactances of said voltage-variable reactance means in accordance with said digital input, a first terminal of said first quadrature hybrid means acting to receive an input signal, a fourth terminal of said first quadrature hybrid means connected to the first terminal of said second quadrature hybrid means and acting to apply the phaseshifted signal to said second quadrature hybrid means, a fourth terminal of said second quadrature hybrid means providing an output signal with the desired phase shift, said voltage-variable reactance means comprising: a varactor diode; a capacitor connected between the anode of said varactor diode and ground potential and acting to provide an A.C. ground to said varactor diode; a first inductor connected between the cathode of said varactor diode and ground; a second inductor connected between the cathode of said varactor diode and an input from said quadrature hybrid means, said inductors acting to linearize the reactive impedance seen by said quadrature hybrid means; and means to apply an analog control voltage at the anode of said varactor diode in order to vary the reactance of said varactor diode.

Claim 3

A digital phase shifter circuit capable of providing 360* phase shifts for use in phased array applications, comprising: first and second quadrature hybrid means, each having four terminals; first and second voltage-variable reactance means connected respectively to the second and third terminals of said four terminals of said first quadrature hybrid means; third and fourth voltage-variable reactance means connected to the second and third terminals respectively of said second quadrature hybrid means, said voltage-variable reactance means acting as reactive loads on their respective quadrature hybrid means, each of said quadrature hybrid means in combination with their respective voltage variable reactance means acting to shift the phase of a input signal by 90* plus the phase shift due to the reactive load on said quadrature hybrid means; and digital-to-analog converter means acting to receive a digital input and convert said digital input into an analog control voltage, said analog control voltage being applied to each of said voltage-variable reactance means and acting to vary the reactances of said voltage-variable reactance means in accordance with said digital input, a first terminal of said first quadrature hybrid means acting to receive an input signal, a fourth terminal of said first quadrature hybrid means connected to the first terminal of said second quadrature hybrid means and acting to apply the phase-shifted signal to said second quadrature hybrid means, a fourth terminal of said second quadrature hybrid means providing an output signal with the desired phase shift, said voltage-variable reactance means comprising linearizing circuits connected in cascade, each of said linearizing circuits comprising: a varactor diode; a capacitor connected between the anode of said varactor diode and ground potential and acting to provide an A.C. ground to said vAractor diode; a first inductor connected at one end to the cathode of said varactor diode, the other end of the first inductor of the first linearizing network of said cascade being connected to said quadrature hybrid means, the other end of the first inductor of the second and subsequent linearizing circuits being connected to the cathode of the varactor diode of the last preceding network; a second inductor connected between the cathode of the varactor diode of the last linearizing circuit in said cascade and ground potential; and means to apply an analog control voltage at the anode of each of said varactor diodes in order to vary the reactance of said varactor diodes.

Claim 4

A digital phase shifter circuit capable of providing 360* phase shifts for use in phased array applications, comprising: first and second quadrature hybrid means, each having four terminals; first and second voltage-variable reactance means connected respectively to the second and third terminals of said four terminals of said first quadrature hybrid means; third and fourth voltage-variable reactance means connected to the second and third terminals respectively of said second quadrature hybrid means, said voltage-variable reactance means acting as reactive loads on their respective quadrature hybrid means, each of said quadrature hybrid means in combination with their respective voltage variable reactance means acting to shift the phase of a input signal by 90* plus the phase shift due to the reactive load on said quadrature hybrid means; and digital-to-analog converter means acting to receive a digital input and convert said digital input into an analog control voltage, said analog control voltage being applied to each of said voltage-variable reactance means and acting to vary the reactances of said voltage-variable reactance means in accordance with said digital input, a first terminal of said first quadrature hybrid means acting to receive an input signal, a fourth terminal of said first quadrature hybrid means connected to the first terminal of said second quadrature hybrid means and acting to apply the phase-shifted signal to said second quadrature hybrid means, a fourth terminal of said second quadrature hybrid means providing an output signal with the desired phase shift, said voltage-variable reactance means comprising linearizing circuits connected in cascade, each of said linearizing circuits comprising: a varactor diode; a capacitor connected between the anode of said varactor diode and ground potential and acting to provide an A.C. ground to said vAractor diode; a first inductor connected at one end to the cathode of said varactor diode, the other end of the first inductor of the first linearizing network of said cascade being connected to said quadrature hybrid means, the other end of the first inductor of the second and subsequent linearizing circuits being connected to the cathode of the varactor diode of the last preceding network; a second inductor connected between the cathode of the varactor diode of the last linearizing circuit in said cascade and ground potential; and means to apply an analog control voltage at the anode of each of said varactor diodes in order to vary the reactance of said varactor diodes.

Claim 5

A quadrature, hybrid phase shifter circuit having a linear phase shift comprising, in combination: a quadrature, hybrid phase shifter having four ports, the first and fourth being for an input and an output signal respectively; a first varactor linearizing network comprising a first lumped inductance, connected at one end to the third port of said phase shifter, a second lumped inductance connected at one end to the other end of said first lumped inductance and at the other end to ground, and a varactor having its cathode connected to the connection between said first and second inductances; a second varactor linearizing network comprising a third lumped inductance, connected at one end to the fourth port of said phase shifter; a fourth lumped inductance connected at one end to the other end of said third lumped inductance and at the other end to ground; a second varactor having its cathode connected to the connection between said third and fourth inductances; and means connected to the cathodes of said varactors for connecting a control voltage thereto.

Claim 6

A quadrature, hybrid phase shifter circuit having a linear phase shift comprising, in combination: a quadrature, hybrid phase shifter having four ports, the first and fourth being for an input and an output signal respectively; a first varactor linearizing network comprising a first lumped inductance, connected at one end to the third port of said phase shifter, a second lumped inductance connected at one end to the other end of said first lumped inductance and at the other end to ground, and a varactor having its cathode connected to the connection between said first and second inductances; a second varactor linearizing network comprising a third lumped inductance, connected at one end to the fourth port of said phase shifter; a fourth lumped inductance connected at one end to the other end of said third lumped inductance and at the other end to ground; a second varactor having its cathode connected to the connection between said third and fourth inductances; and means connected to the cathodes of said varactors for connecting a control voltage thereto.

Claim 7

A quadrature, hybrid phase shifter as in claim 3, further comprising: a first lumped capacitance connected between the anode of said first varactor and ground potential; a second lumped capacitance connected between the anode of said second varactor and ground potential; and wherein the equation for the differential phase shift through said phase shifter is