National Instruments Corporation

Jeffrey Allan Cornell

Kunal H Patel

John G Banaska

Jun Lu

Wendi Song

Matthew Tate Dougan

Xuechen Han

Embodiments are presented herein of an open-loop test system for testing vertical-cavity surface-emitting lasers (VCSELs). A high-speed pulse generator may be used to produce nanoseconds pulses provided to the VCSEL device. A high-speed oscilloscope may be used to measure the resultant nanoseconds pulses across the VCSEL device. The VCSEL device voltage and VCSEL device current may be obtained from the measured nanosecond pulses according to compensation data derived from the system. A pre-test compensation procedure may be used to obtain the compensation data, which may include representative characteristics of each system component. The compensation procedure may also include capturing specified pulse trains under different load conditions of the pulse generator to obtain a scaling relationship between the VCSEL device current and an input voltage used for the pulse generation, and also for obtaining various parameters later used to derive an accurate VCSEL device voltage and an accurate VCSEL device current.

Nanoseconds-pulse based current/voltage measurement for testing vertical-cavity surface-emitting laser

A power converter may have an input stage that includes a pair of transformer coils, switching circuitry to energize the pair of transformer coils according to an input supply voltage provided by an input source, and a limiting circuit coupled between the pair of transformer coils to cause the input stage to stop drawing current from the input source once the amount of charge drawn from the input source reaches a specific value. An output stage of the power converter may receive energy from the pair of transformer coils, and convert the received energy into an output supply voltage. The pair of transformer coils may continue providing energy stored in a leakage inductance of the pair of transformer coils to the output stage for at least a period of time, once the limiting circuit has caused the input stage to stop drawing current from the input supply.

DC-to-DC converter input stage with capacitive current limit

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Austin, TX, United States of America

Jeffrey Allan Cornell