Biosensor device

A biosensor device comprising:

• a signal generator to generate a continuous wave signal;
• an antenna to emit the continuous wave signal as a radio wave;
• a variable matching circuit to perform impedance matching between the signal generator and the antenna;
• a detection circuit to output a detection signal on a basis of the continuous wave signal and a reflected signal of the radio wave, reflected by a human body, and incident on the antenna;
• and
• control circuitry to control a capacitance value of a capacitance element in the variable matching circuit from 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,
• wherein the detection circuit includes:
• a first mixer to multiply the continuous wave signal by the reflected signal;
• a phase shifter to convert a phase of the continuous wave signal by 90 degrees;
• and
• a second mixer to multiply output of the phase shifter by the reflected signal, and wherein the control circuitry stores, in advance, a complex number conversion coefficient having amplitude and phase information,
• the detection signal includes an I signal output from the first mixer of the detection circuit and a Q signal output from the second mixer, and
• when time average values of the respective two signals of I and Q in the detection signal in a predetermined period corresponding to one cycle or more time in which heartbeat and respiration waveforms can be measured are represented by VI and VQ, respectively, a heartbeat waveform signal Vr is represented by Vr=VI−jVQ, and
• when a reflection coefficient of the variable matching circuit and the antenna is represented by Γm,
• the conversion coefficient is calculated by Γm/Vr obtained by dividing the reflection coefficient Γm by the heartbeat waveform signal Vr.