Qualcomm Incorporated

Oregon State University

Lingli Xia

Sameer Wadhwa

Lennart Karl-Axel Mathe

Patrick Yin Chiang

Jiao Cheng

An apparatus, such as a pixel sensor for an ultrasonic imaging apparatus, is disclosed. The apparatus includes a first metallization layer coupled to a piezoelectric layer, wherein a first voltage is formed at the first metallization layer in response to an ultrasonic wave reflecting off an item-to-be-imaged (e.g., a user's fingerprint) and propagating through the piezoelectric layer, and wherein the first metallization layer is situated above a substrate; a second metallization layer situated between the first metallization layer and the substrate; and a device configured to apply a second voltage to the second metallization layer to reduce a parasitic capacitance between the first metallization layer and the substrate.

Pixel receiver with capacitance cancellation for ultrasonic imaging apparatus

Examples of multi-stage programmable rectifiers are provided herein. Each rectifier stage can include a first transistor and a switch connected to the first transistor. A threshold voltage of the first transistor can be programmed through selection of one of a plurality of voltages available at the switch. Each rectifier stage can also include a second transistor that can be connected in series with the first transistor. An output capacitor can be connected to the second transistor at an output of the rectifier stage. The plurality of voltages provided at the switch allows the threshold voltage of the first transistor to be adjusted in either a positive or negative position to increase efficiency of the rectifier. A calibration process can be used to identify the position of each switch in the rectifier stages that results in the highest efficiency or rectifier output voltage.

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Lingli Xia