Matching circuit

Abstract

The present invention has for its object to provide a matching circuit with multiband capability which can be reduced in size, even if the number of handled frequency bands rises. The matching circuit of the present invention comprises a load having frequency-dependent characteristics, a first matching block connected with one end to the load with frequency-dependent characteristics, and a second matching block formed by lumped elements connected in series to the first matching block. And then, when a certain frequency band is used, matching is obtained with the series impedance of the first matching block and the second matching block. When a separate frequency band is used, a π-type circuit is constituted by connecting auxiliary matching blocks to both sides of the second matching block. Next, at the same frequency, by taking the combined impedance of this π-type circuit and a load whose characteristics do not depend on the frequency to be Z 0 , the influence of the second matching block is removed.

1 . A matching circuit making the impedance at predetermined plural frequencies match with an element whose impedance has frequency-dependent characteristics, comprising: 
 a first matching block connected at one end to a first terminal to which said element whose impedance has frequency-dependent characteristics is connected;    one or more second matching blocks consisting of lumped elements and connected in series to said first matching block;    one or more switch elements; and    one or more auxiliary matching blocks connected to said second matching block(s) via said switch element(s).    
   
   
       2 . The matching circuit according to  claim 1 , comprising: 
 N L-type circuits each consisting of one said second matching block and a series circuit of one first said switch element (below referred to as the “first switch element”), connected to one end of said second matching block, and one first said auxiliary matching block (below referred to as the “first auxiliary matching block”); and    N shunt circuit block parts, each consisting of a series circuit of one second said switch element (below referred to as the “second switch element”) and one second said auxiliary matching block (below referred to as the “second auxiliary matching block”); and    wherein    N is an integer equal to or greater than 1,    said N L-type circuits have one end of the second matching block of the first L-type circuit connected in series to said first matching block and one end of the second matching block of the next-stage L-type circuit connected to the other end of said second matching block,    N said shunt circuit block parts are connected to the other end of the second matching block of the last-stage L-type circuit, and    a π-type circuit is formed by a second auxiliary matching block connected to one said second switch element made to conduct, a first auxiliary matching block connected to one said first switch element made to conduct, and the second matching blocks between these.    
   
   
       3 . The matching circuit according to  claim 1 , comprising 
 N L-type circuits each consisting of said second matching block and a series circuit of said switch element, connected to one end of said second matching block, and said auxiliary matching block; and a series second matching block;    wherein    N being an integer equal to or greater than 1,    said N L-type circuits have one end of the second matching block of the first L-type circuit connected in series to said first matching block and one end of the second matching block of the next-stage L-type circuit connected to the other end of said second matching block,    one end of said second matching block is connected to the other end of the second matching block of the last-stage L-type circuit;    the other end of said second matching block is connected to an element whose characteristics do not depend on the frequency, and    a T-type circuit is constituted by one said series circuit, said switch element of which is taken to be in a conducting state, and the second matching blocks on both sides thereof.,    
   
   
       4 . The matching circuit according to  claim 2  or  3 , wherein N equals 1.  
   
   
       5 . The matching circuit according to any of  claims 1  to  4 , 
 wherein said second matching block is constituted by an L-type circuit consisting of a series matching block and a series circuit of a switch element, connected to said series matching block, and a matching element.    
   
   
       6 . A matching circuit, comprising: 
 a first matching block connected at one end to a first terminal to which an element whose impedance has frequency-dependent characteristics is connected; and    a matching circuit part constituting a π-type circuit by a second matching block connected in series to said first matching block, and switch element and auxiliary matching block series circuits respectively connected to both ends of said second matching block; and    wherein said second matching block is constituted by lumped elements.    
   
   
       7 . A matching circuit, comprising: 
 a first matching block connected at one end to a first terminal to which an element whose impedance has frequency-dependent characteristics is connected; and    a matching circuit part constituting a T-type circuit by a second matching block connected at one end to said first matching block, the next second matching block connected at one end to the other end of said second matching block, a series circuit of a switch element, connected between said second matching block and the next second matching block, and an auxiliary matching block; and    wherein said second matching block and said series second matching block are constituted by lumped elements.