Power efficiency optimization method of LC resonant driver for MEMS mirrors

A method to adjust a resonant frequency of an LC driver circuit for a mirror device, the method comprises:

• setting, by a capacitance control circuit, a DC bias for a variable capacitance circuit in an LC driver circuit to an initial value;
• alternately driving, by a driver circuit, energy to the LC driver circuit in a first direction during a first phase of operation, and in a second direction during a second phase of operation;
• sensing, by a sense circuit, an amplitude of an output signal from the mirror device when the mirror device is alternately driven by the driver circuit;
• and
• adjusting, by the capacitance control circuit, the DC bias for the variable capacitance circuit to an adjusted value that is responsive to the sensed amplitude of the output signal from the mirror device until the sensed amplitude reaches a peak value, whereby the peak value of the sensed amplitude corresponds to a well-matched resonant frequency between the LC driver circuit and the mirror device.

A method to adjust a resonant frequency of an LC driver circuit for a mirror device, the method comprises:

• assigning, by a capacitance control circuit, an initial DC bias value for a variable capacitance circuit in an LC driver circuit;
• initializing, by the capacitance control circuit, the variable capacitance circuit to set the initial DC bias value;
• alternately driving, by a driver circuit, energy to the LC driver circuit, wherein a resonant frequency of the LC driver circuit is determined in part by the variable capacitance circuit, parasitic capacitances of the system, and parasitic capacitances of the mirror device;
• capturing, by the capacitance control circuit, an initial peak signal level from a sense circuit when the LC driver circuit is operated by the driver circuit with the initial DC bias value;
• selecting, by the capacitance control circuit, a new DC bias value for the variable control circuit of the LC driver circuit;
• initializing, by the capacitance control circuit, the variable capacitance circuit to set the new DC bias value;
• capturing, by the capacitance control circuit, a new peak signal level from the sense circuit when the LC driver circuit is operated by the driver circuit with new DC bias value;
• comparing the initial peak signal level to the new peak signal level to determine if the peak signal level has increased or decreased;
• when the peak signal level is determined to have increased, continuing in a same direction of the adjustment to the DC bias value;
• when the peak signal level is determined to have decreased for a first time, reversing the direction of adjustment to the DC bias value;
• and
• when the peak signal level is determined to have decreased for a second time, terminating the current adjustment to the DC bias value and reverting to the prior DC bias value.