Infineon Technologies Ag

Siemens Aktiengesellschaft

Robert-Grant Irvine

Werner Veit

Harald Pretl

Josef Fenk

Wolfgang Thomann

Claus Stoeger

A low-noise amplifier circuit is specified which has a switchable gain ratio. For this purpose, a parallel circuit comprising a first and a second current path () is provided between a radio-frequency signal input and output (), with the first current path () having a transistor which is connected in a common-base circuit for signal amplification, and the second current path () having a transistor which is connected in a common-emitter circuit () for signal amplification, and has input impedance matching (). Owing to the good noise characteristics and the good linearity characteristics, the described low-noise amplifier circuit is suitable for use in radio-frequency receivers in which adaptive pre-amplification is required even before a frequency converter, that is to say at the radio-frequency level, because the input signal has a wide dynamic range, such as that in the case of UMTS.

Low-noise amplifying circuit

A circuit configuration for generating an output signal orthogonal to an input signal includes a delay device having an input to which an input signal is applied, an output at which an output signal is available, and a control input for controlling a time lag. A multiplier device has inputs being coupled to the input and the output of the delay device and has an output. A device for low-pass filtering is connected between the output of the multiplier device and the control input of the delay device.

CIRCUIT CONFIGURATIONS HAVING A DELAY DEVICE, A MULTIPLIER, FILTER AND/OR A MASTER-SLAVE FLIP-FLOP FOR GENERATING: AN OUTPUT SIGNAL BEING ORTHOGONAL TO AN INPUT SIGNAL, AN OUTPUT SIGNAL HAVING A FREQUENCY BEING DOUBLE THAT OF AN INPUT SIGNAL, OR TWO OUTPUT SIGNALS BEING ORTHOGONAL TO ONE ANOTHER

An operational amplifier includes a symmetrical end stage being formed of emitter followers. The end stage has output terminals forming outputs of the operational amplifier and has input terminals. A voltage divider is connected between the output terminals of the end stage and has a tap. A first differential amplifier stage has input terminals forming symmetrical inputs of the operational amplifier and has output terminals each being coupled to a respective one of the input terminals of the end stage. Loads each terminate a respective one of the output terminals of the first differential amplifier stage. Two second parallel-connected differential amplifier stages each have a first input terminal connected to a reference potential, a second input terminal connected to the tap of the voltage divider, and an output terminal each being coupled to a respective one of the loads.

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Greensboro, NC, United States of America

Robert-Grant Irvine