Microwave phase shifter and power amplifier

Abstract

A phase shifter according to this invention includes a circuit board having a semi-insulating layer. An active layer is formed in a transmission line forming portion on one surface side of the semi-insulating layer, a first ground conductive layer is formed on the other surface side, a transmission line is formed on the upper side of the active layer, and a second ground conductive layer is formed on the transmission line forming surface of the semi-insulating layer in close proximity to one side of the transmission line. If a bias voltage of negative polarity is applied to the transmission line, reverse bias is applied to the active layer to form a depletion layer and capacitance is equivalently connected to the transmission line having inductance. A phase shift amount can be freely controlled by changing the value of the capacitance according to the bias voltage.

1 - 3 . (canceled)  
   
   
       4 . A microwave phase shifter comprising: 
 a circuit board on which a transmission line to transmit a microwave signal is formed on one surface of a liquid crystal dielectric layer, a first conductive layer is formed on the other surface, and a second conductive layer is formed on a forming surface of the transmission line With an end portion set in close proximity to one side of the transmission line; and    bias circuit which applies bias voltage to the transmission line.    
   
   
       5 . The microwave phase shifter according to  claim 4 , wherein the bias circuit grounds the first and second conductive layers and applies a bias voltage whose polarity is periodically inverted to the transmission line.  
   
   
       6 . The microwave phase shifter according to  claim 4 , wherein the bias circuit variably controls the bias voltage in a continuous or stepwise fashion.  
   
   
       7 - 11 . (canceled)  
   
   
       12 . A power amplifier comprising: 
 distributor which distributes a microwave signal to a plurality of transmission paths;    a plurality of amplifiers respectively provided in the plurality of transmission paths to power-amplify the transmission signals;    phase adjusting circuit which adjusts signal propagation phases between the plurality of transmission paths by using any one of the plurality of transmission paths as a reference path, providing phase shifters in at least the other paths and adjusting phase shift amounts of the phase shifters; and    synthesizer which synthesizes the signals power-amplified by the plurality of amplifiers at ends of the plurality of transmission paths;    wherein the phase shifter includes a circuit board on which a transmission line to transmit a microwave signal is formed on one surface of a liquid crystal dielectric layer, a first conductive layer is formed on the other surface, and a second conductive layer is formed on a forming surface of the transmission line with an end portion set in close proximity to one side of the transmission line, and bias circuit for applying bias voltage to the transmission line, and    the phase adjusting circuit supplies a bias voltage corresponding to the phase shift amount to the phase shifter.    
   
   
       13 . The power amplifier according to  claim 12 , wherein the bias circuit grounds the first and second conductive layers and applies bias voltage whose polarity is periodically inverted to the transmission line.  
   
   
       14 . The power amplifier according to  claim 12 , wherein the bias circuit variably controls the bias voltage in a continuous or stepwise fashion.  
   
   
       15 . The power amplifier according to  claim 12 , wherein the phase shifter is arranged on the output side of the power amplifier.  
   
   
       16 . The power amplifier according to  claim 12 , wherein the phase adjusting circuit includes a monitor which monitors an output signal of the synthesizer and a control device which controls a voltage value of the bias voltage based on the monitoring result of the monitor.  
   
   
       17 . (canceled)  
   
   
       18 . A circuit board of a microwave phase shifter comprising: 
 a liquid crystal dielectric layer;    a transmission line formed on one surface of the liquid crystal dielectric layer to transmit a microwave signal;    a first conductive layer formed on the other surface of the liquid crystal dielectric layer;    a second conductive layer formed on a transmission line forming surface of the liquid crystal dielectric layer with an end portion set in close proximity to one side of the transmission line;    a ground terminal to which the first and second conductive layers are connected; and    a bias voltage input terminal to which the transmission line is connected.