Patent ID: 11950885
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 2:
3. The biosensor device according to claim 1, wherein
the variable matching circuit includes:
a first terminal connected to the signal generator;
second and third terminals connected to the antenna;
a fourth terminal connected to ground;
a first variable capacitance element connected between the first terminal and the second terminal;
a second variable capacitance element connected between the third terminal and the fourth terminal; and
a third variable capacitance element connected between the first terminal and the fourth terminal,
the control circuitry calculates a load impedance Za of the antenna by using
the reflection coefficient Γm of the variable matching circuit and the antenna, the reflection coefficient Γm being determined by multiplying the conversion coefficient by a time average of the detection signal in a predetermined period corresponding to one cycle or more time in which heartbeat and respiration waveforms can be measured on a basis of the detection signal; and
a circuit constant of the variable matching circuit, and
the control circuitry, by using a condition that the reflection coefficient Γm including impedances of the variable matching circuit and the antenna is zero (50Ω) at the load impedance Za of the antenna,
sets an adjustment value for the variable matching circuit so as to satisfy the following formulas,, C
      1
     
     =
     
      2
      
       ω
       ⁢
       
        {
        
         
          X
          a
         
         -
         
          
           ω
           ⁢
           
            C
            2
           
           ⁢
           
            R
            0
            2
           
          
          
           1
           +
           
            
             ω
             2
            
            ⁢
            
             
              
               C
               2
              
              (
              
               
                R
                0
               
               -
               
                R
                2
               
              
              )
             
             2
            
           
          
         
        
        }
       
      
     
    
   
  
  
   
    
     
      C
      2
     
     =
     
      
       1
       ω
      
      ⁢
      
       
        
         
          R
          0
         
         -
         
          (
          
           
            2
            ⁢
            
             R
             1
            
           
           +
           
            R
            a
           
          
          )
         
        
        
         
          (
          
           
            R
            2
           
           -
           
            R
            0
           
          
          )
         
         ⁢
         
          {
          
           
            
             (
             
              
               R
               2
              
              -
              
               R
               0
              
             
             )
            
            ⁢
            
             (
             
              
               R
               a
              
              +
              
               2
               ⁢
               
                R
                1
               
              
             
             )
            
           
           -
           
            
             R
             2
            
            ⁢
            
             R
             0
            
           
          
          }
         
        
       
      
     
    
   
  
 

in which a capacitance value of each of the first variable capacitance element and the second variable capacitance element is represented by C1,
a value of a series resistance parasitic on each of the first variable capacitance element and the second variable capacitance element is represented by R1,
a capacitance value of the third variable capacitance element is represented by C2,
a value of a series resistance parasitic on the third variable capacitance element is represented by R2, and
a frequency of a signal generated from the signal generator to generate the continuous wave signal is represented by ω.