Abstract: One embodiment of the invention includes an on-chip current-sense system for measuring a magnitude of an output current through a power transistor. The system includes a first sense transistor that conducts a first reference current to or from a phase node and a second sense transistor configured to conduct a second reference current to or from a power rail. The first and second sense transistors can be substantially identical and can be proportionally matched to the power transistor. An OTA receives the first and second reference currents and a third reference current that flows to or from the phase node and generates a sense current that is proportional to the output current in response to the first, second, and third reference currents. A sense circuit compares the sense current with a predetermined magnitude and generates an over-current signal in response to the sense current being greater than the predetermined magnitude to indicate an over-current condition of the output current.

Abstract: One embodiment of the invention includes a hysteretic power regulator system. The system includes a switching stage configured to periodically couple an input voltage to an inductor in response to a control signal to generate an output voltage. The system also includes a hysteretic control stage configured to generate the control signal based on a comparison of a feedback voltage associated with the output voltage and a predetermined reference voltage. The system also includes a feed-forward stage configured to generate a feed-forward ramp voltage in response to the control signal. The feed-forward ramp voltage can be added to the feedback voltage to set a frequency of the control signal. The system further includes a compensation stage configured to cancel a DC error associated with the feed-forward ramp voltage relative to the feedback voltage to substantially mitigate errors associated with the output voltage.

Abstract: A system for implementing current shaping for retract of a voice coil motor (VCM) includes drive circuitry coupled to drive the VCM according to a logic state of the system. Current shaping circuitry is configured to temporarily decrease the bandwidth of a VCM transconductance loop in response to a control signal. The transconductance loop includes at least the VCM, the current shaping circuitry and the drive circuitry. The system also includes logic configured to provide the control signal at an end portion a drive logic state to enter a current shaping logic state as a transition from the drive logic state to a floating logic state to reduce current through the VCM such that acoustic emissions from the VCM are mitigated during the retract.

Abstract: An electrical apparatus comprising an amplifier having a first input, a second input, and an output. The apparatus further comprises a first electrical path coupled to the first input and having a first resistance and a first electrical path coupled to the second input and having a second resistance. The apparatus further comprises a second electrical path coupled to the second input and having a third resistance and a second electrical path, comprising an electrically-controllable resistance, coupled between the output and the first input. Further, the apparatus comprises circuitry for controlling the electrically-controllable resistance for adjusting a ratio between the electrically-controllable resistance and the third resistance to approximate a ratio between the first resistance and the second resistance.

Abstract: System and method for high-speed and high-precision digital to analog conversion. A preferred embodiment comprises a dual-resistor ladder digital-to-analog converter with a coarse resistor ladder and a fine resistor ladder, wherein resistors in the fine resistor ladder are implemented using transistors. When the effective resistances of switches used in a switching circuit are properly matched with the resistance of the resistors, the differential non-linearity and the integral non-linearity of the digital-to-analog converter can be minimized. The use of transistors to implement switches and resistors can help to eliminate mismatches arising from different fabrication steps and materials, further improving the performance of the digital-to-analog converter.

Abstract: System and method for high-speed and high-precision digital to analog conversion. A preferred embodiment comprises a dual-resistor ladder digital-to-analog converter with a coarse resistor ladder and a fine resistor ladder, wherein resistors in the fine resistor ladder are implemented using transistors. When the effective resistances of switches used in a switching circuit are properly matched with the resistance of the resistors, the differential non-linearity and the integral non-linearity of the digital-to-analog converter can be minimized. The use of transistors to implement switches and resistors can help to eliminate mismatches arising from different fabrication steps and materials, further improving the performance of the digital-to-analog converter.

Abstract: A configurable voltage regulator (128) operable in either of two selectable modes or topologies is disclosed. In one disclosed embodiment, the voltage regulator (128) can operate as a charge pump regulator or a switching regulator, to generate a negative polarity regulated voltage. The voltage regulator (128) includes an output driver (80), for example including first and second drive transistors (81A, 81B), that are used in both of the selectable modes.

Abstract: An apparatus for controlling an actuator having a moveable member and having a coil that influences movement of the member, by provision of a drive current to the coil in response to a target speed voltage signal. The apparatus includes a sensing unit (11) for sensing a voltage corresponding to the voltage across said coil and providing a first signal (BEMF) corresponding to the sensed voltage and indicative of the velocity of the moveable member. The apparatus further includes a generation circuit (13) for providing a second signal (TBEMF) indicative of a target voltage corresponding to a target velocity for the moveable member and a controller (12) receiving the first signal and the second signal and responsive thereto for determining a compensation signal characterized as an analog type response regulated to the target voltage for effectuating the target velocity.

Abstract: A configurable voltage regulator (128) operable in either of two selectable modes or topologies is disclosed. In one disclosed embodiment, the voltage regulator (128) can operate as a charge pump regulator or a switching regulator, to generate a negative polarity regulated voltage. The voltage regulator (128) includes an output driver (80), for example including first and second drive transistors (81A, 81B), that are used in both of the selectable modes.

Abstract: A method of signal compression of a signal to reduce the large dynamic range, for example, of the output signal of a CD player in such a way that soft passages of a piece of music are reproduced in somewhat louder manner and very loud passages of a piece of music some are reproduced in somewhat less loud manner. The signal compression circuit used therefor can be integrated completely. The audio signal is fed over a volume control, which can be adjusted by the user, and to this end, a digital setting signal in accordance with the adjustment made on the user side, is supplied via a bus line. When the audio signal is strongly increasing, a tracking signal is formed of said signal, with the amplitude thereof being dependent on the medium amplitude of the audio signal. A window comparator compares the tracking signal with a reference value, as a consequence of which the contents of the up/down counter are reduced. This reduced value is added via an adder to the digital setting signal for the volume control.

Abstract: An SC filter with intrinsic anti-alias function for adjustably decreasing or increasing the amplitude of audio signals in a predetermined frequency range. The SC filter includes a filter module having an RC network with at least one frequency-response-determining RC member whose resistor component R is realized in SC technology. The SC filter also includes a setting means connected to the filter module such that its setting determines the frequency response of the SC filter. The setting means also renders possible a neutral setting in which the effective audio signal path of the SC filter circumvents the filter module so that no decrease or increase of the amplitude of individual frequency portions takes place. An anti-alias low pass filter unit is connected into the audio signal path when the setting means is not set to the neutral setting and the anti-alias low pass filter unit is not located in the audio signal path when the setting means is set to the neutral setting.

Abstract: In an integrated circuit comprising a so-called “switched” capacitor, the latter is switched by a parallel circuit of two complementary switching transistors having mutually complementary switching pulse trains. Due to parasitic effects during this switching operation, disturbing offset voltages arise at the switched capacitor. In order to avoid such offset voltages, the edges of the one switching pulse train are shifted in time with respect to the corresponding edges of the complementary switching pulse train. To this end, a switching pulse generator contains a delay member fed with a control signal which is formed by means of a constant reference voltage using a dummy or simulation of that circuit that contains the switched capacitor.