Abstract: A method and apparatus for greatly increasing the output voltage or current transformation ratio in an impedance transformation amplifier are disclosed. Broadly, the method takes advantage of multiple, phase-synchronized impedance transformation stages, each of which preferably contributes an equal portion of the eventual output voltage or current.

Abstract: A method of adding a minimum pulse width to the switching devices of both outputs of a switching differential pair enhances the performance of a switching amplifier. When used with similar switching devices at similar temperatures, this results in injecting a similar error term into both sides of a differential output, thus presenting it as a null common-mode output. That is, by correlating the output to differences between the differential pairs, accurate representations by the switching device outputs are achieved. Although the invention is described in conjunction with two switching devices per side of the differential output pair, operation with three or more switching devices per side, as seen in multi-reference amplifiers, may be accommodated by the invention.

Abstract: Centering pulses within the output sample period corrects for instantaneous phase errors in multi-reference switching amplifiers. In the preferred embodiment, the pulses are ordered by the relative magnitude of each switched reference.

Abstract: Methods and apparatus regulate the output of a switching device to a voltage near that of saturation. In the preferred embodiment, this is accomplished for a small period of time during activation before and/or after device saturation. The switching device drive requirement is then measured to attain the regulated voltage. Measurement of the drive requirement during the small period of time correlates to switching driver current, being reliant on the finite gain of the switching device.

Abstract: Apparatus and methods for driving multiple output stages with a single switching amplification modulator reduce system cost and complexity. The technique also addresses applications wherein one or more of several output stages of potentially differing output powers are desired at one time. That is, the switching drivers and loads can be the same or different.

Abstract: A system and method are directed to measuring incoming transition widths by counting asynchronous clock pulses, deriving a reference shortest validated width, and using the shortest validated width for comparison in discriminating further incoming pulse widths.

Abstract: A method and apparatus are disclosed for inferring amplifier load current from an internal control voltage governing a reference voltage in a multi-reference amplifier. Multi-reference amplifiers typically use internally-regulated references for application to the output stage. In that the output devices of these regulators exhibit limited gain or transconductance, internal voltage variances can be observed as a function of reference load current. This invention solves such problem at negligible additional cost.

Abstract: Feedback for self-calibration of any parameter in an analog and/or digital system is described wherein a system quality factor can be represented by a voltage or current differential. The preferred embodiment is operative to alternately supply two or more optimally equivalent currents or voltages from such a system, detect amplitude and/or phase feedback of resultant output signal at the frequency of the alternation, and use feedback to modify a calibration value, voltage, or current so as to minimize or maximize the feedback, thus effecting self-calibration of the system. Such a method and attendant apparatus enables system self-calibration without need of any high-precision or high-cost components.

Abstract: A method and apparatus for detecting output current in switching power supplies forgoes the need for any resistor or other components in series with the load. A method according to the invention includes the steps of inferring the peak current through the inductor as a function of input voltage and inductor charge time, and deriving the current available to the load based upon the flyback voltage during discharge of the inductor. Although a disclosed example is based upon a buck/boost topology, other converter topologies are anticipated. In terms of apparatus, in a switching power supply of the type wherein a switching device is used to charge an inductor that discharges to a load, the invention provides devices arranged for detecting output current without the need for a resistor or other component in series with the load.

Abstract: A method of enhancing the performance of an inductive boost amplifier includes the steps of detecting the specific load impedance being drive by the amplifier, and adjusting the operation of the amplifier to accommodate the detected load impedance. Various load impedances may be connected to the improved amplifier while accommodating the impedance of different amplifier loads subject to change under various conditions such as temperature, voltage, frequency, etc. Thus, in addition to compensation of static load impedance variances, the present invention is quite effective in compensating for dynamic variances as well. Although the description focuses on variable load impedance compensation, it is anticipated that simpler implementations of the technique may be used to selectively switch output filter components into operation in response to specific load impedance ranges, yielding a similar, albeit coarser, net result.

Abstract: A method and apparatus for greatly increasing the output voltage or current transformation ratio in an impedance transformation amplifier are disclosed. Broadly, the method takes advantage of multiple, phase-synchronized impedance transformation stages, each of which preferably contributes an equal portion of the eventual output voltage or current.

Abstract: Circuitry generates a secondary reference voltage in a multi-reference amplifier as a function of a primary reference. As such, the secondary reference equals a known, fixed portion of the primary reference, thereby minimizing distortion due to variations in voltage (or current) ratio. A zero detector is used to monitor incoming data. When the input data is zero, the integral of primary or high-voltage reference represents pulse-width data of ‘one.’ This integral is compared with the integral presented to load through the buffer amplifier, such that the high-voltage reference integral commands a non-inverted output. The output of the amplifier across the load drives the digital integrator to produce higher or lower data values at its output, when enabled by the zero detector. The data value output of digital integrator is converted to a pulse-width train by pulse-width modulator, filtered, buffered, and switched to the load as the secondary reference voltage.

Abstract: The filtered output of multiple possible voltage levels are AC-coupled to a load. An incoming data stream provides input to a pulsewidth modulator which issues control voltages to three or more switching devices, respectively. A first switching device provides a controlled connection to the incoming power supply (V+), a second switching device provides a controlled connection to a lower reference voltage (VR), and a third switching device provides a controlled connection to common, or ground. The common connection of switching devices provides an input to an inductor, which, in conjunction with a capacitor removes out-of-band components before presentation of the output to one side of load. Another capacitor provides a pseudo-ground for the second side of load in a manner consistent with the art of AC-coupled power amplifiers.

Abstract: A method and accompanying circuitry for asynchronous data demodulation uses sorted pulsewidth measurement based on an asynchronous clock. Lock-on of the data stream by such a system is accomplished by measured pulsewidth, rather than inferred frequency. The method broadly comprises the steps of measuring a temporal aspect of the asynchronous clock, and locking onto the data stream in accordance with the measured periods. In the preferred embodiment, the temporal aspect is a ratio of measured periods. Conveniently, a ratio of 2:1 may be used.

Abstract: A method and apparatus facilitate a voltage multiplication into the output stage of a switching amplifier. A plurality of switching devices are used to modulate the interconnection between a power supply, a reactance and a load in accordance with a modulation signal, such that the voltage across the load exceeds the supply voltage. In the situation where the reactance is a capacitor, the voltage across the load exceeds the supply voltage by two or an integer multiple thereof. In the preferred embodiment, a pair of reactances and attendant switching devices are used to modulate the interconnection between the supply voltage relative to both sides of the load depending upon the sign of the modulation signal.

Abstract: A method and attendant circuitry reduces the number of regulatory and switching devices in a multi-reference switching amplifier. In the preferred embodiment, multiple independently-modulated effective references are summed at a load through use of both linear and switched control of switching devices.

Abstract: A method and circuitry are disclosed that provide for linear operation of a flyback converter through zero output. Broadly, the preferred embodiment enforces a minimum control pulse width thereby isolating energy derived thereby from the eventual load, and dissipating the energy from the minimum control pulse width. The net effect is linear operation inclusive of zero output.

Abstract: A method and apparatus for greatly increasing the output voltage or current transformation ratio in an impedance transformation amplifier are disclosed. Broadly, the method takes advantage of multiple, phase-synchronized impedance transformation stages, each of which preferably contributes an equal portion of the eventual output voltage or current.

Abstract: A method of improving modulation resolution in a flyback converter by pulsewidth- and/or position-modulation of a subtractive constant current with specific timing considerations is applicable to boost or buck/boost topologies. A typical system of this type uses a pulsewidth-modulated (PWM) circuit to provide a control pulsewidth in response to an incoming data stream. The control pulsewidth is used to drive a switching device which, when energized, charges an inductor. When the switching device is released the energy stored in the inductor “flies back” through a diode into a capacitor and load resistance. According to this invention, a constant current sink, gated under control of the PWM controller, is used to improve modulation resolution through pulsewidth- and position-modulation of a subtractive constant current with specific timing considerations. In the preferred embodiment, the constant current sink is implemented using a transistor in conjunction with a resistor network.

Abstract: A method of selectively reducing the impedance presented to the load of a reactive impedance transformation amplifier output stage reduces distortion caused by load reactance. A control circuit is interconnected to a gated switch on at least one side of the load, and the switch is controlled to shunt back-EMF from the load. In one embodiment, the shunting action is initiated when the released energy would approach zero with a purely resistive load. Since the delay time may be a function of energy released, the delay from energy release to shunt initiation is optimally a function of the energy storage time of the inductor. In the event that this energy storage time is regulated using feedback, the shunt delay should be as well regulated, to accentuate the regulatory action. In a more comprehensive embodiment, the amplifier output polarity is inverted and its output caused to be a function of the positive error in the circumstance of a substantial positive error, such as that caused by an inductive load.