Abstract: An integrated circuit (IC) differential amplifier is disclosed. The differential amplifier comprises two amplifier stages each containing a transistor amplifier stage connected to one of the inputs of a push-pull input (RFin, RFXin) and a cascode stage connected to one of the outputs of a push-pull output (RFout, RFXout), where the cascode stages can be switched by a changeover switch (DC gain switch).

Abstract: A balanced voltage reference circuit has a transistor that is operated as an emitter follower and to whose base two resistors are connected in series for beta compensation of the balanced circuit. One end of the smaller resistor which faces away from a transistor base, the smaller resistor being split into two resistor elements, is connected inside the chip to a signal point of an amplifier circuit whose operating point can be adjusted. In which case, one end of an integrated capacitance is connected, as a parallel element of an RC filter, between the two resistor elements of the smaller resistor.

Abstract: A low-noise amplifier stage with reversible amplification includes a first series circuit of load paths of two transistors which is connected through a resistor to ground. A second series circuit or n series circuits of load paths of two transistors is likewise connected through a resistor to ground and is connected parallel to the first series circuit. Parallel-connected collectors of the first transistors of the series circuits are connected through an oscillator circuit to a supply voltage terminal. Two reference voltage sources are provided for supplying a first reference voltage to base terminals of the first transistors of the series circuits and for supplying a second reference voltage to base terminals of the second transistors of the series circuits. A reversing device connects a node point of the load paths of the transistors of the second series circuit to a supply voltage terminal as a function of a control signal.