New thermometer for RF and microwave thermal therapy using MMIC in Si BJT VCO type

A new wireless-thermometer is proposed for thermal therapy that uses a silicon bipolar transistor voltage controlled oscillator (Si VCO), based on three-dimensional (3D) MMIC technology. The method for detecting temperature is examined. As the result, the VCO's oscillation frequency (around 4.35 GHz) is extremely linear against temperature from 30/spl deg/C to 50/spl deg/C. Tests using a phantom material show that a prototype thermometer can be read through at least 7 cm of soft tissue.