Phase shifter

A phase shifter comprising:

• (i) a phase shift unit comprising
• a reactance unit including a first variable capacitance device, and
• a susceptance unit including a second variable capacitance device, connected to said reactance unit;
• and
• (ii) a control unit for outputting a common control signal to said phase shift unit,
• wherein said first variable capacitance device and said second variable capacitance device are made up with a predetermined capacity ratio such that said first variable capacitance device and said second variable capacitance device are controllable by the common control signal,
• wherein the control signal is such that the following expression constant is maintained:
• Z
• 0
• =
• X
• B
• wherein Z0 represents characteristic impedance, X represents reactance for said reactance unit, and B represents susceptance for said susceptance unit.

A phase shifter comprising:

• (i) a plurality of phase shift units serially connected, each comprising:
• a reactance unit including a first variable capacitance device and a fixed inductance device, wherein the reactance unit is connected to an adjacent reactance unit, and
• a susceptance unit including a second variable capacitance device, connected to said reactance unit, wherein the reactance unit, the adjacent reactance unit, and the susceptance unit form a T-section, and wherein the first variable capacitance device and the second variable capacitance device have a capacity ratio such that the first variable capacitance device and the second variable capacitance device are controllable by a common control signal;
• and
• (ii) a control unit for outputting the common control signal to said phase shift units,
• wherein the control signal is such that the following expression constant is maintained:
• θ
• =
• tan
• -
• 1
• -
• B
• -
• 2
• ⁢
• X
• +
• B
• ⁢
• ⁢
• X
• 2
• 2
• ⁢
• (
• 1
• -
• B
• ⁢
• ⁢
• X
• )
• ⁢
• .
• wherein Z0 represents characteristic impedance, X represents reactance for said reactance units, and B represents susceptance for said susceptance units.