Abstract: A circuit array for frequency translation by means of quadrature heterodyne signals has very low quadrature errors even at very high frequencies and is monolithically integratable with little external circuitry. The circuit array includes a first mixer which receives a first portion of an input signal, a second mixer which receives a second portion of the input signal, and a heterodyne signal generator which receives a local oscillator signal and supplies quadrature heterodyne signals to the mixers. The heterodyne signal generator includes a control loop to ensure a 90.degree. phase shift between the quadrature heterodyne signals. The circuit array can be used in a modulator for a transmitter or in a demodulator for a receiver.

Abstract: A controllable broadband amplifier whose current consumption and direct voltage output level are independent of the control voltage includes four differential amplifiers, each having two input ports, two output ports, and a shared port. The two input ports of the first differential amplifier are connected to the two signal input ports of the broadband amplifier, the shared port of the first differential amplifier is connected to the power supply port via a constant current source, and the output ports of the first differential amplifier are connected to the shared ports of the second and third differential amplifiers. The input ports of the second and third differential amplifiers are connected together and to control voltage input ports of the broadband amplifier. One output port of the second differential amplifier is connected to one output port of the third differential amplifier, and both are connected to the shared port of the fourth differential amplifier.