US 6,320,480 B1 · Wideband low-loss variable delay line and phase shifter

Abstract

A programmable phase shifter (20, 40, 54, 60, 62) includes a variable delay line formed from a nonlinear transmission line (NLTL) (26, 28, 46, 28), which enables the device to be used in applications where the frequency of the input signal varies. A variable DC bias applied to the NLTL (26, 28, 46, 48) varies the NLTL's phase velocity and delay. Since the characteristic impedance of a transmission line changes as a function of the DC bias, the input voltage standing wave ratio (VSWR) also changes. In order to compensate for the change in the input VSWR, a pair of NLTLs (26, 28, 46, 48) are coupled at the input and output to a pair of hybrid couplers (22, 42). In an alternate embodiment of the invention, the hybrid couplers (22, 24) are replaced with 180° power splitters (42, 44) in order to reduce distortion of the device. In other embodiments of the invention (40, 54), a nonlinear transmission lines are used to form both discretely variable and continuously variable digital phase shifters (60, 62).

Claims13

Dependent claims

A phase shifter comprising:

a first hybrid coupler including first and second input ports and first and second output ports;
a second hybrid coupler including third and fourth input ports and third and fourth output ports;
a pair of nonlinear transmission lines (NLTLs) connected between said first and second output ports and said third and fourth input ports;
a first termination impedance coupled to said second input port, said first input port for receiving an input signal;
and
a second termination impedance coupled to said third output port, said fourth output port for outputting an output signal.

3 more elements

Dependencies are inferred from the claim text.

Wideband low-loss variable delay line and phase shifter

Life of this patent

Wideband low-loss variable delay line and phase shifter

Life of this patent

Abstract

Claims13