Bae Systems Information and Electronic Systems Integration Inc.

Aaron B Johnson

David J Schorr

James H Steenson, Jr

Walter J Sears

A method and system are provided for the monitoring of direct current bias, the system including switching an amplifier of known scale factor from low to high; monitoring a step change in bias generated by the gain change; measuring, the response to the bias change via appropriate peak detection logic; and determining the amount of bias present at an input based on AC response and the amplifier scale factor.

DC bias evaluation in an AC coupled circuit via transient gain response

An accurate and rapid method for characterizing the performance of an APD and setting its operating voltage Vop to an optimal value uses an on-board LED or other pulsed light source to measure APD responses at different operating voltages Vop. An estimated breakdown voltage Vb is determined by comparing the measured responses, and the Vop is adjusted to a new value at a fixed offset from the estimated Vb. The fixed offset is selected according to ambient light conditions, including the presence or absence of light background noise, and whether the sun is partially or fully in the field of view. The method is iterated until convergence, or until a maximum number of iterations is reached. In embodiments, a plurality of APD's having a common Vop can be adjusted, and the Vop is never set below a minimum value VopBW necessary to meet timing requirements for a missile guidance system.

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Merrimack, NH, United States of America

Aaron B Johnson