Maxim Integrated Products, Inc.

Fingerprint Cards Anacatum IP Ab

Benjamin Willcocks

Miguel Valencia

Rolf Sundblad

David Carling

Peter Almers

Nicholas Weiner

Christopher J Born

Sayed A Madni

A method of controlling operation of a field-powered biometric device comprising biometric acquisition circuitry, processing circuitry controllable to transition between a first functional state having a first power consumption and a second functional state having a second power consumption lower than the first power consumption, and power management circuitry. The method comprises the steps of monitoring, by the power management circuitry, a property indicative of a supply voltage to the processing circuitry; controlling, when the monitored property indicates that the supply voltage has fallen to a first threshold voltage, the processing circuitry to transition from the first functional state to the second functional state; and controlling, when the monitored property indicates that the supply voltage has increased to a second threshold voltage higher than the first threshold voltage, the processing circuitry to transition from the second functional state to the first functional state.

Field-powered biometric device, and method of controlling a field-powered biometric device

Techniques are described for adaptive sampling qualification for extinction ration control. The techniques may be implemented in a laser driver assembly which includes a laser driver and a sampling loop configured to facilitate sampling of photodiode current produced by a monitor photodiode (MPD) of an optical transmitter assembly. The sampling loop comprises a low pass filter with reset, a digital-to-analog converter (DAC), and a comparator. The filter receives transmit (Tx) data provided to the laser driver and generates an output corresponding to a number of consecutive bits of a first type received in the transmit (Tx) data. The filter resets the output when a bit of a second type is received. The digital-to-analog converter (DAC) outputs a threshold signal. The comparator compares the output from the low pass filter and the threshold signal, and outputs a signal indicating when the photodiode current is to be sampled.

Adaptive sampling qualification for extinction ratio control

An optical measurement system configured to determine whether an optical transmitter signal requires calibration is disclosed. In an implementation, the system includes an optical transmitter configured to emit electromagnetic radiation in limited spectrums of wavelengths at amplitudes based upon one or more transmission signals, and an optical sensor configured to detect the electromagnetic radiation in the limited spectrums of wavelengths and to generate a signal in response thereto. The system includes reference current sources configured to generate a respective reference current and a switch configured to transition between a first configuration and a second configuration based upon the transmission signals. The reference currents are configured to subtract from the signal generated by the optical sensor such that a difference remains. A comparison device is configured to compare the difference portion to a reference signal and output a signal indicative of the direction in which an optical transmitter driver signal should be adjusted.

Direct reference subtraction system for control of optical transmitters

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Bristol, United Kingdom

Benjamin Willcocks