MEMS capacitive sensor biasing circuit including an integrated inductor
AssigneeRobert Bosch GmbH
InventorJohn M. Muza
Life of this patent
Estimating the term…
Abstract
A MEMS capacitive sensor biasing circuit. The circuit includes a high-voltage (HV) NMOS switch, an inductor, a diode, and a capacitor. The HV NMOS switch has a source coupled to ground. The inductor has a first node coupled to a drain of the HV NMOS switch, and a second node coupled to a DC power source supplying a first DC voltage. The diode has an anode coupled to the first node of the inductor and the drain of the HV NMOS switch. The capacitor has a first node coupled to a cathode of the diode, and a second node coupled to the ground.
Claims17
A MEMS chip, the chip comprising:
- a high-voltage (HV) NMOS switch having a source coupled to ground;
- an inductor having a first node coupled to a drain of the HV NMOS switch, and a second node coupled to a DC power source supplying a first DC voltage, the inductor integrally formed as part of the MEMS chip;
- a diode having an anode coupled to the first node of the inductor and the drain of the HV NMOS switch;
- and
- a capacitor having a first node coupled to a cathode of the diode, and a second node coupled to the ground;
- wherein the MEMS chip is a capacitive sensor biasing circuit.
A method of generating a bias voltage for a capacitive sensor by a MEMS chip including a high-voltage (HV) NMOS switch having a source coupled to ground, an inductor integrally formed as part of the MEMS chip and having a first node coupled to a drain of the HV NMOS switch, and a second node coupled to a DC power source supplying a first DC voltage, a diode having a anode coupled to the first node of the inductor and the drain of the HV NMOS switch, and a capacitor having a first node coupled to a cathode of the diode, and a second node coupled to the ground, the HV NMOS switch, the method comprising:
- driving the HV NMOS switch closed, coupling the ground to the anode of the diode and the first node of the inductor;
- driving the HV NMOS switch open, causing a current to flow from the inductor through the diode to the capacitor;
- repeating the driving of the HV NMOS switch open and closed causing the capacitor to charge to a voltage greater than the first DC voltage;
- and
- charging the capacitor to a second DC voltage, the second DC voltage having a magnitude greater than the first DC voltage.
Dependencies are inferred from the claim text.