Abstract: A system for controlling carrier leakage in a communications device includes a first mixer unit operable to receive and convert a first signal into a second signal having a higher frequency than the first signal, and to transmit the second signal, a second mixer unit operable to receive, convert the second signal into an in-phase signal and a quadrature signal each having lower frequency than the second signal, and transmit them, a processor coupled to the first mixer and the second mixer to perform a leakage reduction procedure by receiving and sampling the in-phase signal and the quadrature signal, determining that a result from the sampling is not equal to a predetermined value, initiating a transmission of a direct current offset signal to the first mixer unit, and adjusting a voltage of the direct current offset signal until a next result of the sampling approximately equals the predetermined value.

Abstract: One embodiment of the invention includes a power regulator system. The system includes a switching system configured to generate an output voltage across a load based on a high-side switch coupling a power voltage to an output at an edge-trigger of a PWM control signal having an activation pulse-width of the high-side switch. The system also includes a switch driver system configured to set a duty-cycle of the PWM control signal such that the activation pulse-width of the PWM control signal is based on the power regulator system operating in one of a continuous conduction mode (CCM) and a discontinuous conduction mode (DCM). The edge-trigger of the PWM control signal can occur based on a relative magnitude of the output voltage and the power voltage while operating in the DCM.

Abstract: A comparator has a differential input stage, a current source coupled to the differential input stage for providing a tail current to one side of the differential input stage, and a differential load coupled to the differential pair and having at least one diode coupled load transistor per differential side. A load current through either one of the at least one diode coupled load transistor on either differential side is mirrored with a current mirror configuration to provide a current be fed to a respective node, each node being coupled to a respective variable biasing current source and a respective other side of the differential input stage, so as to provide a variable positive feedback to the differential input stage.

Abstract: In a method and system for sensing current in a switching regulator (SWR) operating in a current mode, a power switch is coupled to receive the current from a switching element, the power switch being controlled by a gate signal. An inrush of the current causes an initial transient spike (ITS). A buffer having a buffer input and a buffer output is coupled to receive the gate signal and provide a buffered gate signal. The buffer output is disabled during the ITS. A sense switch (SW) is coupled to receive a portion of the current from the switching element, the SW being turned on by the buffered gate signal after the initial transient spike. A sense resistor (SR) is coupled to receive the portion of the current from the SW. An amplifier converts the portion of the current through the SR to a voltage signal for controlling the SWR.

Abstract: One embodiment of the invention includes a system for regulating an output voltage of a power converter. The system comprises an error amplifier that compares a feedback voltage associated with the output voltage with a reference voltage to generate an error signal that is employed to control a magnitude of the output voltage. The system also comprises a plurality of sample and hold circuits each configured to sample an error amplifier output voltage to provide the error signal. The system further comprises a switching controller configured to control switching of the error amplifier output voltage between each of the plurality of sample and hold circuits in response to a change in an output load of the power converter.

Abstract: Various systems and methods for determining potential battery failure are disclosed. For example, some embodiments of the present invention provide battery systems that include a battery, an embedded processor and a computer readable medium. The computer readable medium includes instructions executable by the embedded processor to measure at least one characteristic of the battery; to calculate a rate of change of internal impedance of the battery based at least in part on the at least one characteristic of the battery; and to determine a potential failure condition based on the rate of change of internal impedance of the battery.

Abstract: An ASK demodulator for use in an RFID transponder having a limiter circuit associated with the antenna circuit and converting the ASK antenna field strength modulation into an ASK limiter current modulation by limiting the antenna voltage to a fixed value and thereby causing the limiter current to be substantially proportional to the ASK antenna field strength, and a current discriminator circuit that discriminates the ASK limiter current modulation. By converting the field strength modulation into a proportional limiter current and discriminating that limiter current, a linear relationship and a stable demodulator sensitivity are achieved. The current discrimination can be made accurately under low-voltage conditions.

Abstract: One embodiment of the present invention includes a power supply system. The power supply system comprises a variable voltage source configured to provide and incrementally increase a control voltage associated with a pass-transistor. The power supply system also comprises an inrush current monitor configured to monitor a current-flow through the pass-transistor. The power supply system further comprises a voltage control circuit configured to halt the incremental increase of the control voltage in response to the current-flow exceeding a predetermined current limit.

Abstract: A keep alive circuit for recharging bootstrap capacitors in multiple totem-pole switching power stages using N-channel field effect transistor or NPN bipolar junction transistor switching devices during 100% or substantially 100% duty cycle operation of one of the totem pole pairs.

Abstract: A circuit to appropriately adjust the emission intensity of LEDs of various colors. By means of a first optical sensor (11), the detection range of which includes the peak wavelengths of LEDs (10R), (10G), and (10B) of multiple colors and the detectable peak wavelength of which is shorter than the shortest peak wavelength of the LEDs (10R), (10G) and (10B), and a second optical sensor 12 the detectable peak wavelength of which is longer than the longest peak wavelength of the LEDs (10R), (10G), and (10B), the LEDs (10R), (10G), and (10B) of each color are lighted one color at a time and the emission intensity is measured. When the measurement result of the first optical sensor (11) indicates an increase and the measurement result of the second optical sensor indicates a decrease, it is known that the emitted light has shifted to a shorter wavelength, and in the opposite case, that it has shifted to a longer wavelength.

Abstract: One embodiment of the invention includes a power regulator system. The system comprises at least one current regulator configured to maintain a substantially constant current flow through each of at least one series connected light emitting diode (LED) string. The system also comprises a power converter configured to generate an output voltage to provide power to the at least one current regulator and the at least one series connected LED string. The system further comprises a voltage regulator configured to determine a voltage that provides power to the at least one current regulator and to adjust the output voltage based on the determined voltage to mitigate power loss due to excessive voltage provided to power the at least one current regulator.

Abstract: A radio frequency identification (RFID) transponder (FIGS. 4 and 5A) is disclosed. The transponder includes first (RF) and second (GND) terminals. A first resonant circuit (500, 504, 508) is connected between the first and second terminals. A second resonant circuit (502, 504, 508) has a second resonant frequency different from the first resonant frequency and is connected between the first and second terminals.

Abstract: Methods and apparatus to test electronic devices are disclosed. An example method includes setting a first controlled switch to prevent a current detect signal from tripping an overcurrent protection event controlling an operation of the device; setting a second controlled switch to route a first sensed voltage associated with the device to a voltage adjuster; sending a calibration current corresponding to a target threshold current through the device; detecting the first sensed voltage while the calibration current flows through the device; and setting a reference signal substantially equal to the first sensed voltage, wherein the reference signal is to be used to generate the current detect signal.

Abstract: Generating a bandgap reference by generating a first current in a first circuit and a second current in a second circuit, a control circuit forcing the first and second currents to have a first magnitude proportional-to-temperature. Generating a third current in a third circuit having a second magnitude based on a first voltage associated with the first circuit, the second magnitude being complementary-to-temperature. Adding the first and second magnitudes in a fourth circuit to form a third magnitude substantially constant over change in temperature, the fourth circuit generating a fourth current having the third magnitude. Adding the first and second magnitudes to generate a fifth current having the first magnitude in a fifth circuit and a sixth current having the second magnitude in a sixth circuit, the fifth and sixth circuits sinking current from the fourth circuit.

Abstract: In accordance with an aspect of the present invention, an external FET driving circuit includes a driving portion, a drain-to-gate clamp portion and a current feedback portion. The driving portion provides a driving signal to the external FET. The drain-to-gate clamp portion protects the external FET from flyback current, when the external FET is quickly turned OFF. The current feedback portion controls the driving signal provided by the driver.

Abstract: Methods and apparatus for analyzing an integrated circuit are disclosed. An example method includes supplying power to an on-chip supply power regulator of integrated circuit, instructing the on-chip supply power regulator to output a circuit supply signal having a desired minimum voltage level for the integrated circuit, instructing the integrated circuit to initiate an on-chip self-test process, analyzing the results of the on-chip self-test process, and repeating the process after stepping down the voltage of the circuit supply signal level.

Abstract: A ground fault detection device includes a sense coil including a primary winding and a secondary winding to detect current in a line conductor and a neutral conductor. It also includes a capacitor in parallel with the secondary winding and a virtual inductor to form a resonance circuit having a signal proportional to the current and being indicative of a ground fault condition.

Abstract: In an apparatus for monitoring a supply voltage, a current mirror coupled to the supply voltage provides a pair of matching currents. A resistor divider that includes a first resistor coupled in series with a second resistor to from a first node is disposed between the supply voltage and a voltage reference. A pair of transistors that have their bases coupled to the first node are coupled to receive a corresponding one of the pair of matching currents. A collector of a first transistor of the pair of transistors provides an output voltage in response to the supply voltage. A third resistor is disposed between an emitter of a second transistor of the pair of transistors and the voltage reference. A base and a collector of a third transistor are coupled to the first node and an emitter is coupled to the voltage reference.

Abstract: A backlight device that is not affected by offset voltage. Driving transistor (41) operates such that current flows in LED circuit (11), and the detection voltage generated by current detector (42) and the reference voltage are input alternately to first input transistor (30a) and second input transistor (30b) of amplifier (20). Brightness adjusting switch (43) operates such that when driving transistor (41) is turned OFF during the OFF period of LED circuit (11), for example, during the horizontal blanking interval or vertical blanking interval, the detection voltage and the reference voltage are swapped, so that the average voltage generated in current detector (42) is equal to the reference voltage, and the effect of the offset voltage can be eliminated.

Abstract: Methods and apparatus to provide power distribution switch circuits with fast responses to hard short-circuits are disclosed. In one example, a power distribution switch to detect a hard short-circuit condition is described, comprising a switching device having a resistance between an input terminal and an output terminal, to conduct a current from an input power source having an input voltage to an output terminal having an output voltage, a voltage feedback loop having a digital output voltage to increase the resistance of the switching device in response to a short-circuit based on the output voltage, and an analog current feedback loop to increase the resistance of the switching device based on a current through the switching device and a reference current.