Voltage-Controlled Oscillator with Schmitt Trigger Inverter Utilizing a Reverse Biased Diode

This study presents a small-sized voltage-controlled oscillator utilizing a Schmitt trigger inverter. A Schmitt trigger inverter which has two threshold voltages can be a relaxation oscillator in a single-stage configuration so can reduce elements contained in an oscillator circuit from conventional ring-oscillator conducted with an odd number of stages. To limit the current in the feedback circuit, the MOSFET's diode is connected in reverse biased, allowing for a smaller capacitor and reduced circuit size. The oscillator can operate over a wide frequency range based on the input gate voltage. This circuit is designed using the 180-nm process from ROHM. With the proposed circuit, the oscillation frequency ranges from approximately 40 Hz to 159 MHz, power consumption ranges from approximately 93 to 144 µW, and the area of the circuit is 134 µm2.