A Single-Pixel Sensor for Near-field Imaging Based on Startup Time of Oscillator

In this letter, a novel near-field imaging method based on the startup time of the oscillator is proposed and validated by a circuit implemented in the 55-nm CMOS process. An interdigitated capacitor (IDC) is used as the sensor element and embedded in the oscillator. The simulation and measurement results show that the sensing oscillator’s startup time increases with the permittivity of material under test (MUT) accordingly. The core area of the near-field sensor is 0.154 mm
$\times \,\, 0.123$
mm and the power consumption is 2.7 mW. The small area and low power consumption make it quite suitable for near-field imaging array and biomaterials detection.