Siemens Aktiengesellschaft

Infineon Technologies Ag

Stephan Weber

Volker Thomas

Johann-Peter Forstner

Dietmar Wenzel

Stefan Heinen

Georg Lipperer

A circuit for providing a base operating voltage for a bipolar transistor includes a Umultiplier providing, in response to a working-point control current, a working voltage fed to a circuit for reducing the working voltage in order to generate a base operating voltage smaller than a base-emitter voltage drop of a bipolar power transistor. With this, the bipolar power transistor may be maintained in the class C operation in a flexible and robust manner, so that an amplifier with high efficiency is obtained.

Circuit for providing a base operating voltage for a bipolar transistor and amplifier circuit

A circuit chip has an apparatus for an electrically conductive connection of a terminal thereof to an external reference potential. The apparatus has a parallel connection of a bonding wire and a semiconductor area formed in a substrate of the circuit chip. The semiconductor area is doped higher than the substrate of the circuit chip.

Apparatus for connecting an IC terminal to a reference potential

An additional control voltage is used to adjust then operating point of a power amplifier. The amplitude of the control voltage is a measure of the maximum gain needed during the current time slot and which is already provided to the power amplifier before the beginning of the active time slot. This enables an individual adjustment of the operating point so that the power consumption can be reduced.

Optimization of the operating point of power amplifiers in mobile stations

A reference stage is provided in order to compensate for manufacturing tolerances, for example relating to the threshold voltage of a transistor. This reference stage has a transistor which is a physical equivalent of the transistor to be trimmed in a radio-frequency amplifier stage. In particular, this reference transistor has the same electrical direct current characteristics as the amplifier transistor. A reference voltage can be tapped off across a resistor on the reference stage and can be supplied to a control amplifier which uses this reference voltage to set the operating point of the radio-frequency amplifier transistor such that manufacturing tolerances are compensated for. Such radio-frequency power amplifiers are used, for example, as transmit amplifiers in mobile radios.

Amplifier circuit

An electrical circuit is provided for controlling nonlinear paths. A first linearization block and a second linearization block are provided, which may each have a characteristic curve that is the inverse of that of the control path. The first linearization block is configured in a feedback path running from the output of the control path to an input of a regulator. The second linearization block is configured for supplying a reference variable to an input of the regulator. Nonlinearities in the control path are thus linearized. In consequence, major changes in the reference variable are acceptable. The linearization blocks can be designed in a simple manner and require only a small surface area, since low power levels are normally produced at the inputs of an operational amplifier contained in the regulator. An additional advantage resulting from this is compensation for temperature drift of the two linearization blocks. The described regulator is suitable, for example, for controlling a transmission amplifier, as is used in mobile radio applications.

Circuit configuration for controlling nonlinear paths

A differential amplifier includes two channels. Each channel has an input, an output, an emitter transistor, and a first current source. The channels are connected to one another via a resistor. In at least one of the two channels, a potential-shifting device is assigned to the first current source. A voltage-controlled, second current source is provided for linearization purposes. A third current source forms the output of the differential amplifier.

Differential amplifier having two channels

A controllable LC oscillator circuit has a resonant circuit including an inductance and a capacitance disposed in parallel. The oscillator is driven by an amplifier and the inductance is produced using coupled coils. The effective inductance of the coupled coils can be set by changing a gain of the amplifier, and a magnitude of the coupling factor of the coupled coils defines a magnitude of an adjustable frequency band of the oscillator.

Controllable LC oscillator circuit

A circuit configuration for digitally setting analog parameters includes at least two analog multiplying devices each having a differential amplifier stage. The differential amplifier stages have differential inputs connected in parallel with one another and driven by an analog bipolar input signal. The differential amplifier stages have outputs coupled to one another cumulatively. The differential amplifier stages receive supply currents which are to be switched on and off individually as a function of a corresponding digital control signal and are graded using binary code.

Circuit configuration for digitally setting analog parameters

An interface circuit for transmitting binary signals includes a signal transmitting device, a signal receiving device and a transmission device connected therebetween. The signal transmitting device has a device for limiting steepness of ascending and descending edges of the binary signals to certain inclination values which are identical to one another.

Interface circuit

A circuit for determining and evaluating a data signal with a disturbing direct voltage portion has a signal processor with which the direct voltage portion is determined and then subtracted from the signal. A non-linear control is provided that changes a time constant of the circuit in dependence on the signal curve.

Circuit for determining and evaluating a data signal on which a direct

The amplifier stage of the invention has a first and a second differential amplifier branch and a first and a second impedance-burdened branch. The first impedance-burdened branch is connected in parallel with the input impedance of the first differential amplifier branch, and the second impedance-burdened branch is connected in parallel with the input impedance of the second differential amplifier branch. As a result, it is possible to maintain the amplifier parameters largely constant.

Amplifier stage with constant input impedance

A circuit for generating a reference potential includes a first transistor having an emitter connected to a ground potential, a base, and a collector connected to the base; a second transistor having a base connected to the base of the first transistor; a first resistor connected between the collector of the first transistor and an output terminal outputting the reference potential; a second resistor connected between the collector of the second transistor and the output terminal; a third resistor connected between the emitter of the second transistor and ground potential; a third transistor having a base connected to the collector of the second transistor, and an emitter connected to the ground potential; a fourth transistor having a collector connected to a supply potential, an emitter connected to the output terminal, and a base connected to the collector of the third transistor; a first current source connected between the base and the collector of the fourth transistor; and a second current source connected in parallel with the first current source, the second current source generating a compensation current compensating for current fluctuations of the first current source.

Circuit configuration for generating a reference potential

A circuit configuration for offset compensation includes a filter device for ascertaining a direct component in an input signal delivered to it and a linking device for subtractive linking of the input signal and an output signal of the filter device. A tracking and holding device which is connected between the filter device and the linking device is controllable by a control signal. The control signal is furnished by a window comparator device having an input to which the input signal is applied. When the input signal is within a predetermined window, the tracking and holding device is located in a tracking mode, while otherwise it is in a holding mode.

Circuit configuration for offset compensation

A low-pass filter circuit including a first sub-filter designed in integrated circuit technology. The first sub-filter includes high-impedance resistor elements and smaller capacitances. A second sub-filter preceding the first sub-filter is constructed with low-impedance resistor elements and higher capacitances.

Filter circuit arrangement

In a circuit for determining and storing an average signal value, an overlaid dc voltage part is identified and subtracted from the actual signal. To this end, an all-pass filter with which both a transfer response is optimized and the error is minimized is utilized in a signal processing means in addition to a low-pass filter.

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Munich, Germany

Stephan Weber