Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A decision feedback equalizer includes at least one quantizer, able to quantize a received signal according to a comparison with a one of multiple quantization thresholds. Each quantization threshold corresponds to one or more than one value of one or more than one previously received symbols. The equalizer further includes level selection circuitry, for setting the quantization thresholds based on statistical measurements taken in connection with signals having the corresponding value of one or more previously received signal.

Abstract: A method is disclosed for recovering a digital signal from an analog signal. A received analog signal value is compared with a centre threshold, and with at least one of a pair of outer thresholds, to form comparator output signals. Digital samples of the comparator output signals are formed using a recovered clock signal. The values of the outer thresholds are adapted such that a constant proportion of the digital samples represent received signal values lying between the outer thresholds, and the phase of the recovered clock signal is adapted such that the separation of the outer thresholds is maximised. Other receiver parameters can be adapted in the same way.

Abstract: There is disclosed a method of transferring data from a first device to a second device over parallel connections. The data represents a signal which has some known statistical property, and the data is encoded and distributed between the parallel connections, such that each parallel connection carries a respective time-aligned sequence of bits, and such that the known statistical property of the signal represented by the data is used to establish a known correlation between the respective sequences. In the second device, the known correlation between the respective sequences is used to re-establish time alignment of the received sequences.

Abstract: A timing-based servo system for positioning a magnetic head relative to a magnetic storage medium, the magnetic storage medium having a servo pattern written thereon, the system comprising a head including a servo read element configured to read the servo pattern and produce a signal, the signal including recognizable signal events corresponding to the servo read element reading servo transitions; a servo decoder configured to receive the servo signal, determine the position of the head, with respect to the servo band, in response to the amount of time between the signal events, and generate an error signal indicative of actual head position relative to desired head position with respect to the servo band, the servo decoder including time capture logic configured to determine the amount of time between the signal events, the time capture logic including a multiple phase clock generator.

Abstract: An adaptive media speed drive unit for use with a magnetic storage medium, the magnetic storage medium having a timing based servo pattern written thereon, the servo pattern including transitions, the drive unit including a magnetic head including a servo read element configured to read the servo pattern and produce a signal, the signal including recognizable signal events corresponding to the servo read element reading servo transitions; a servo decoder including time capture logic configured to determine the amount of time between the signal events; and a digitally controlled oscillator configured to produce a tracking clock which a write element can use to write data to the magnetic medium with a uniform spacing regardless of magnetic medium speed.