Athletic activity may be tracked while providing encouragement to perform athletic activity. For example, energy expenditure values and energy expenditure intensity values may be calculated and associated with a duration and type of activity performed by an individual. These values and other movement data may be displayed on an interface in a manner to motivate the individual and maintain the individual's interest. The interface may track one or more discrete “sessions”. The sessions may be associated with energy expenditure values during a duration that is within a second duration, such as a day, that is also tracked with respect to variables, such as energy expenditure. Other individuals (e.g., friends) may also be displayed on an interface through which a user's progress is tracked. This may allow the user to also view the other individuals' progress toward completing an activity goal and/or challenge.

Athletic activity may be tracked while providing encouragement to perform athletic activity. For example, energy expenditure values and energy expenditure intensity values may be calculated and associated with a duration and type of activity performed by an individual. These values and other movement data may be displayed on an interface in a manner to motivate the individual and maintain the individual's interest. The interface may track one or more discrete “sessions”. The sessions may be associated with energy expenditure values during a duration that is within a second duration, such as a day, that is also tracked with respect to variables, such as energy expenditure. Other individuals (e.g., friends) may also be displayed on an interface through which a user's progress is tracked. This may allow the user to also view the other individuals' progress toward completing an activity goal and/or challenge.

To provide a device for measuring a time of passage that is capable of sensing passage of the torso more accurately than a photoelectric cell while maintaining the ease of use of a photoelectric cell, passage of a runner is sensed by causing the upper portion of the body of the runner to be broadly illuminated by infrared light, visible light, and/or other such electromagnetic waves, and by detecting light reflected from large part(s) of the body of the runner.

To provide a device for measuring a time of passage that is capable of sensing passage of the torso more accurately than a photoelectric cell while maintaining the ease of use of a photoelectric cell, passage of a runner is sensed by causing the upper portion of the body of the runner to be broadly illuminated by infrared light, visible light, and/or other such electromagnetic waves, and by detecting light reflected from large part(s) of the body of the runner.

A power detection circuit for detecting powering down of a voltage domain in an integrated circuit is disclosed. The power detection circuit is placed in or near the voltage domain in the integrated circuit to provide power detection on the integrated circuit. The power detection circuit detects powering down of the voltage domain to provide an isolation enable signal to another voltage domain that interfaces with the powering down voltage domain. The isolation enable signal may be used by an isolation cell coupled to the non-powering down voltage domain to prevent corrupted logic being received from the powering down voltage domain.

A digital-to-time converter (DTC) and methods of calibrating the same reduces or mitigates nonlinearity and thus improves DTC performance. A slope of a voltage signal of the DTC is calibrated using a capacitor and a comparator. Capacitance of the capacitor and/or maximum current of a current source is adjusted to configure the comparator to output a signal during a second phase when a reference voltage signal is at or above a first level and below a second level. Calibrating gain of the DTC includes adjusting a time difference between an output signal of the DTC set at a first digital code value and the output signal of the DTC set at a second digital code value to be one period of a clock signal input to the DTC. Calibrating integral nonlinearity of the DTC includes measuring a time period for each of multiple digital code values of the DTC.

An analog-to-digital converter includes: a voltage-current converter receiving an analog input voltage, generating a first digital signal from the analog input voltage, and outputting a residual current remaining after the first digital signal; a current-time converter converting the residual current into a current time in a time domain; and a time-digital converter receiving the residual time, and generating a second digital signal from the residual time, wherein the first digital signal and the second digital signal are sequences of digital codes representing respective signal levels of the analog input voltage.

A pulse-width modulation (PWM) image sensor is described herein. The PWM image sensor may have a stacked configuration. A top wafer of the PWM image sensor may have a charge-to-time converter and a logic wafer, stacked with the top wafer, may include a time-to-digital converter. The PWM image sensor may utilize variable transfer functions to avoid highlight compression and may utilize non-linear time quantization. A threshold voltage, as input to a charge-to-time converter, may additionally be controlled to affect light detection, dynamic range, and other features associated with the PWM image sensor.

This application relates an activity detector (100) for detecting signal activity in an input audio signal (S.sub.IN), such as may be used for always-on speech detection. The activity detector has a first time-encoding modulator (TEM) 101 including a first hysteretic comparator (201) for generating a PWM (pulse-width modulation) signal based on the input audio signal. A second TEM (103) having a second hysteretic comparator (401) is arranged to receive a reference voltage (V.sub.MID) and generate a clock signal (S.sub.CLK). A time-decoding converter (102) receives the clock signal and generates count values of a number of cycles of the clock signal in periods defined by the PWM signal. An activity monitor (104) is responsive to a count signal (S.sub.CT) from the TDC 102 to determine whether the input audio signal comprises signal activity above a defined threshold.

A switched-capacitor amplifier comprises a comparator, sample and amplification capacitors and a controller to control charge and discharge current sources in dependence on an output signal of the comparator. A closed loop control circuit is configured to determine the delay of the comparator and control an offset of the comparator in response to the determined delay.