The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 2026
Filed:
Nov. 18, 2024
Stmicroelectronics International N.v., Geneva, CH;
Ranieri Guerra, S. Giovanni la Punta, IT;
Abstract
According to an embodiment, a driver circuit for a light emitter in a photoplethysmography (PPG) system includes a main control loop with an operational amplifier and a transistor configured as a source follower. During a preset control phase, a preset circuit sets the operational amplifier output voltage to a preset level. A switching circuit activates the preset circuit during the preset phase and the main control loop during the main control phase. The preset circuit preconditions the gate voltage of the source follower transistor to near its threshold voltage before the main control loop activates. This improves start-up performance by reducing delay and uncontrolled initial current while avoiding the need for amplifier trimming. The circuit enables fast settling time and precise control of short current pulses with very low duty cycles, benefiting PPG measurement accuracy and power efficiency in wearable health monitoring devices.