Abstract: Chopper amplifiers with low intermodulation distortion (IMD) are provided. To compensate for IMD, at least one distortion compensation channel is included in parallel with chopper amplifier circuitry of a main signal channel. Additionally, output selection switches are included for selecting between the output of the main signal path and the distortional compensation channel(s) over time to maintain the output current continuous. Such IMD compensation can be realized by filling in missing current of the main signal channel using the distortion compensation channel(s), or by using channel outputs only when they have settled current.

Abstract: Chopper amplifiers with low intermodulation distortion (IMD) are provided. To compensate for IMD, at least one distortion compensation channel is included in parallel with chopper amplifier circuitry of a main signal channel. Additionally, output selection switches are included for selecting between the output of the main signal path and the distortional compensation channel(s) over time to maintain the output current continuous. Such IMD compensation can be realized by filling in missing current of the main signal channel using the distortion compensation channel(s), or by using channel outputs only when they have settled current.

Abstract: A method includes: calculating a first calibration temperature based on a first ratio of a known external voltage to a delta voltage that is a difference between first and second base-emitter voltages of first and second sensing transistors, calculating a first sensed temperature based on a second ratio of the first base-emitter voltage to the delta voltage, adjusting one or more temperature fitting parameters based on a comparison of the first sensed temperature with the first calibration temperature; activating the on-chip heater; calculating a second calibration temperature based, at least in part, on a third ratio of the known external voltage to the delta voltage, calculating a second sensed temperature based on a fourth ratio of the first base-emitter voltage to the delta voltage, adjusting at least one of the one or more temperature fitting parameters based on a comparison of the second sensed temperature with the second calibration temperature.

Abstract: A method includes: calculating a first calibration temperature based on a first ratio of a known external voltage to a delta voltage that is a difference between first and second base-emitter voltages of first and second sensing transistors, calculating a first sensed temperature based on a second ratio of the first base-emitter voltage to the delta voltage, adjusting one or more temperature fitting parameters based on a comparison of the first sensed temperature with the first calibration temperature; activating the on-chip heater; calculating a second calibration temperature based, at least in part, on a third ratio of the known external voltage to the delta voltage, calculating a second sensed temperature based on a fourth ratio of the first base-emitter voltage to the delta voltage, adjusting at least one of the one or more temperature fitting parameters based on a comparison of the second sensed temperature with the second calibration temperature.

Abstract: A phase-domain delta-sigma (??) modulator in a phase digitizer determines a demodulated phase error based on a phase-modulated frequency signal, in which a carrier frequency is modulated with a fundamental frequency and an associated phase, and a selected one of a set of reference signals, where the demodulated phase error represents a difference between the phase and a reference phase of the selected one of the set of reference signals. Moreover, a digital filter in the phase-domain ?? modulator filters the demodulated phase error. Furthermore, a latch in the phase-domain ?? modulator provides a bit stream by sampling one or more bits of the filtered demodulated phase error, where an average value of the bit stream represents the phase. Next, control logic in the phase-domain ?? modulator selects the one of the set of reference signals.

Abstract: A phase-domain delta-sigma (??) modulator in a phase digitizer determines a demodulated phase error based on a phase-modulated frequency signal, in which a carrier frequency is modulated with a fundamental frequency and an associated phase, and a selected one of a set of reference signals, where the demodulated phase error represents a difference between the phase and a reference phase of the selected one of the set of reference signals. Moreover, a digital filter in the phase-domain ?? modulator filters the demodulated phase error. Furthermore, a latch in the phase-domain ?? modulator provides a bit stream by sampling one or more bits of the filtered demodulated phase error, where an average value of the bit stream represents the phase. Next, control logic in the phase-domain ?? modulator selects the one of the set of reference signals.

Abstract: An analog-to-digital converter (ADC) is described. This ADC converts an analog signal into a digital value using a two-pass digitization process. In a first operation, coarse digitization is performed by an averaging converter based on a set of references. Then, in a second operation, fine digitization is performed by either another averaging converter or the same averaging converter based on a subset of the set of references that is progressively closer to an instantaneous value of the analog signal. For example, the coarse digitization may be performed by a low-resolution ADC stage and the fine digitization may be performed by a sigma-delta ADC, such as a single-bit sigma-delta ADC. Moreover, the other averaging converter may use dynamic element matching to shuffle reference elements used to generate the subset. In this way, the ADC may provide high resolution with reduced nonlinearity and quantization noise.

Abstract: During operation of the device, a drive circuit may provide a drive signal having a fundamental frequency to two electrothermal filters (ETFs) having different temperature-dependent time constants. In response to the drive signal, the two ETFs may provide signals having the fundamental frequency and phases relative to the drive signal corresponding, respectively, to the time constants of the ETFs. Then, phase-shift values of the phases may be measured using a phase detector, and a signal may be output based on the phase-shift values. Note that the signal may correspond to a value that is a function of a temperature of the device.

Abstract: An electrothermal frequency-locked loop (EFLL) circuit is described. This EFLL circuit includes an oscillator in a feedback loop. A drive circuit in the EFLL circuit generates a first signal having a fundamental frequency, and an electrothermal filter (ETF) in the EFLL circuit provides a second signal based on the first signal. This second signal has the fundamental frequency and a phase (relative to the first signal) that corresponds to a temperature-dependent time constant of the ETF. Moreover, a sensing component in the EFLL circuit determines a parameter associated with a temperature of the ETF. For example, the parameter may be the temperature or may be other than the temperature, such as the fundamental frequency and/or the phase of the second signal.

Abstract: Current-feedback instrumentation amplifiers that include dynamic element matching for the input transconductance amplifiers by periodically swapping the transconductance amplifiers between the instrumentation amplifier input and the feedback input. The instrumentation amplifiers may include a gain error reduction loop, which loop corrects differences in the gains of the input transconductance amplifiers and eliminates the ripple in the instrumentation amplifier output caused by the dynamic element matching. If chopper stabilization is used, the amplifiers may also include an offset reduction loop. Various embodiments are disclosed.

Abstract: Ripple reduction loop for chopper amplifiers and chopper-stabilized amplifiers. The ripple reduction loop includes a first chopper, a first amplifier having an input coupled to an output of the first chopper, a second chopper having an input coupled to an output of the first amplifier, a second amplifier having an input coupled to an output of the second chopper, a third chopper, an output of the second amplifier having its output capacitively coupled to an input of the third chopper as the only input to the third chopper, a third amplifier coupled as an integrator having an input coupled to an output of the third chopper, an output of the integrator being coupled to combine with the output of the first amplifier as the input of the second chopper, and at least one Miller capacitor coupled between an output of the second amplifier and the input of the second amplifier. Various embodiments are disclosed.

Abstract: An electrothermal frequency-locked loop (EFLL) circuit is described. This EFLL circuit includes an oscillator in a feedback loop. A drive circuit in the EFLL circuit generates a first signal having a fundamental frequency, and an electrothermal filter (ETF) in the EFLL circuit provides a second signal based on the first signal. This second signal has the fundamental frequency and a phase (relative to the first signal) that corresponds to a temperature-dependent time constant of the ETF. Moreover, a sensing component in the EFLL circuit determines a parameter associated with a temperature of the ETF. For example, the parameter may be the temperature or may be other than the temperature, such as the fundamental frequency and/or the phase of the second signal.

Abstract: When a reference signal is generated for a digital-to-analog converter in the feedback path of a sigma-delta modulator, the reference signal can contain modulated error signals, for example when the reference generator implements dynamic element matching. By controlling the reference signal generation in dependence on the bitstream output from the sigma-delta modulator, the effects of intermodulation of the reference signal with the bitstream can be reduced.

Abstract: A rotary magnetic head device for a helical scanning magnetic recording and reproducing apparatus includes a rotary drum, a thin-film magnetic head (6) protruding from the rotary drum in a diametrical direction for coming into contact with a magnetic tape (7), obliquely wound around part of the outer peripheral surface of the rotary drum, and head control circuit for adjusting the protrusion of the magnetic head (6) in the diametrical direction. The head control circuit includes a feed-forward control arrangement (9) to bring and hold the magnetic head into a protruded position in which the magnetic head exerts a constant normal force on a tape (7) wound around the drum.

Abstract: A graphic tablet includes a number of parallel electrodes whereto a series of patterns is presented in order to determine the position of a pen relative to the electrodes. As a result of such presentation, a series of code elements is formed on an electrode, which series can be picked up by the pen and is representative of the relevant electrode. When the patterns are suitably chosen, a short series of patterns suffices, so that the determination of the position requires less time.

Abstract: In a data processing system comprising a graphic tablet and a wireless stylus cooperating with the tablet, the stylus is activated by an activation signal transmitted by a display screen integrated with the tablet. For the activation signal use is made of a signal which is transmitted any way by the display screen in the normal operational mode. The stylus is arranged to receive the signal and to change over from a battery-saving standby mode to an operational mode upon reception of this signal.

Abstract: A touch screen device includes a panel; a sensor coupled to the panel for detection of a force applied to the panel and a data processor coupled to the sensor for processing data transmitted by the sensor upon detection of the force. The sensor is provided to be co-deformable with the panel for detecting a deformation of the panel itself as a result of the force being applied. This avoids the use of a rigid frame as in conventional devices, saving weight, costs and components, and reducing manufacturing problems. The sensor means may comprise strain gauges that are physically integrated with the panel. Combined with a display such device presents a minimum parallax.

Abstract: A data processing device comprises a touch screen with a touch position sensor. The position sensor is suitable to detect a touch position on the screen from a change in a current pattern in a conductive panel. The device also comprises a touch force sensor provided with a second conductive panel which extends substantially parallel to the touch screen. The screen is at least partly movable relative to the second panel in a direction transversely of the second panel. The force sensor is suitable to determine a force from a capacitance value between the touch screen and the second panel. The device is suitable for the combined processing of the position and force detected in response to touching.

Abstract: A graphical tablet and a stylus interact electromagnetically with one another. The stylus includes a coil and a transducer to affect an inductance of the coil in response to a force exerted on a tip of the stylus. The transducer comprises first and second ferrite cores. The cores are mounted to move with respect to one another in response to the force. The cores are substantially in contact with one another in the absence of the force. Disengaging causes a well detectable jump in the inductance.