Abstract: A wireless communication unit comprises a transmitter having a power amplifier biased by a bias circuit and a controller operably coupled to the bias circuit for setting one or more bias levels of the power amplifier. The bias circuit is a single bias circuit and is configured to provide either a current mode bias control of the power amplifier or a voltage mode bias control of the power amplifier in response to a control signal from the controller. In this manner, a single bias control circuit can be used to support applications that benefit from both current mode bias control and voltage mode bias control of the power amplifier.

Abstract: The output power of an RF power amplifier is controlled using a feedback loop including a differential integrator for controlling the amplifier's bias voltage. The gain of integration in the differential integrator is varied so as to compensate for variations in the derivative of the power amplifier output power versus the bias voltage.

Abstract: The output power of an RF power amplifier is controlled using a feedback loop including a differential integrator for controlling the amplifier's bias voltage. The gain of integration in the differential integrator is varied so as to compensate for variations in the derivative of the power amplifier output power versus the bias voltage.

Abstract: A transconductance amplifier comprising a first input circuit having a first feedback loop; a second input circuit having a second feedback loop; a resistor having a first interface connected to the first input circuit and a second interface connected to the second input circuit; a first differential pair having a first transistor arranged to control current flow in the first feedback loop to maintain a voltage at the first interface of the resistor at substantially a constant voltage relative to an input voltage applied to the first input circuit and a second transistor arranged to control current flow for a first output; and a second differential pair having a third transistor arranged to control current flow in the second feedback loop to maintain a voltage at the second interface of the resistor at substantially a constant voltage relative to an input voltage applied to the second input circuit and a fourth transistor arranged to control current flow for a second output.

Abstract: A power supply monitor circuit is configured to monitor the state of a power supply, such as a battery, while drawing little power from the power supply and using relatively few device components and thus less on-chip resistance. The circuit includes a reference voltage circuit and a comparator circuit. The reference voltage circuit is adapted to receive a power supply voltage signal from the power supply and supplies a reference voltage signal having a voltage magnitude representative of the power supply voltage level. The comparator circuit receives the reference voltage signal from the voltage reference circuit and supplies an output signal having a voltage magnitude of either a first value or a second value, depending on the value of the reference voltage signal. The monitor circuit reduces the power supply voltage signal by about a bandgap, and the comparator circuit is implemented as a current mode bandgap circuit that merges the reference voltage with a comparator function.

Abstract: A transconductance amplifier comprising a first input circuit having a first feedback loop; a second input circuit having a second feedback loop; a resistor having a first interface connected to the first input circuit and a second interface connected to the second input circuit; a first differential pair having a first transistor arranged to control current flow in the first feedback loop to maintain a voltage at the first interface of the resistor at substantially a constant voltage relative to an input voltage applied to the first input circuit and a second transistor arranged to control current flow for a first output; and a second differential pair having a third transistor arranged to control current flow in the second feedback loop to maintain a voltage at the second interface of the resistor at substantially a constant voltage relative to an input voltage applied to the second input circuit and a fourth transistor arranged to control current flow for a second output.

Abstract: A device for regulating the amplitude of a chrominance signal includes a variable gain amplifier having an input receiving a sub-carrier signal, and an output providing a regulated sub-carrier signal. The gain of the amplifier is controlled by two regulation loops. The first regulation loop operates during the duration of the reference burst. The second regulation loop operates during the visible line. Each of these loops include an up/down counter controlled by a clock. A digital-analog converter has an input receiving the output signals from the first and second up/down counters. An output signal from the digital-analog converter is connected to the gain control of the amplifier. The digital-analog amplifier is controlled by another clock.

Abstract: The demodulating device for a chrominance signal includes an oscillator with a controlled frequency, and an adjuster for adjusting the oscillator frequency as a function of a charge voltage of a memory capacitor. The adjuster preferably includes a fine adjustment channel to output a first adjustment value that depends on the charge voltage of the memory capacitor, and a coarse adjustment channel to output a second adjustment value. The second adjustment value is modified when the charge voltage of the memory capacitor is not within a given range. The device is used, for example, in integrated SECAM decoders.

Abstract: The SECAM chrominance signal demodulator includes an oscillator with a controlled frequency, a phase comparator with a first input connected to an oscillator output, a second input to receive a chrominance signal, and an output connected to an input loop of the oscillator. The demodulator further includes a fixed current source, also connected to the loop input, a current mirror to copy a current equal to the sum of the fixed current and a comparator output current in the output branches comprising first and second calibration resistors respectively, in series with a common resistor. Output voltages corresponding to the red and blue components of the chrominance signal are measured at the terminals of the calibration resistors respectively. The demodulator is used in television sets, for example.

Abstract: A current-controlled oscillator includes a capacitor, and at least one current source for providing at least one charge current for charging the capacitor. A discharge circuit sequentially discharges the capacitor with a discharge current. A control circuit maintains a mean charge voltage of the capacitor at a preset value by controlling the discharge current. The control circuit includes a current control source forming a current mirror with the at least one current source. The current control source is connected to the discharge circuit for setting the discharge current substantially equal to a sum of the charge currents. The oscillator further includes a correction circuit for correcting the discharge current corresponding to a mean charge of the capacitor.