Patent ID: 6559705
Filing Date: 2003-05-06
Classification: G06G,H03D,H03F,H03G

Abstract:
A circuit arrangement (100) for generating and amplifying a DC signal, referred to as level voltage, whose value is essentially proportional to the logarithm of the voltage amplitude of the input signal, the circuit arrangement comprising an amplifier circuit having at least two amplifier stages (10; 20; 30), characterized in thatat least a differential amplifier stage (40), in particular non-negatively fed back, is arranged parallel to the last amplifier stage (30), particularly parallel to the collector circuits of the last amplifier stage (30), the differential amplifier stage (40) precedes at least a multiplier stage (50) for multiplying the output signals of the differential amplifier stage (40), for generating two differential amplifier output signals which are to be multiplied by each other, and alternatively to the differential amplifier (40), the collector currents of the transistors (36, 38) of the rectifier circuit (35) of the last amplifier stage (30) are used, and at least a current adder unit (80) is provided for adding the level voltage of the output signal of the multiplier stage (50) to the respective level voltage of the other amplifier stages.