| 摘要 |
A known linear RF detector comprises a detector part having a detector diode (D1a) biased with a bias current (Ib), and a linearizer part having an operation amplifier (OA1) and a diode in its feedback path. The major drawback of the known detector concerns the output offset voltages, the values of which can be predicted only if the diodes are matched diodes and have the same temperature. Because of this, the detector part and the linearizer part cannot be placed on different circuit boards. The invention solves the problem by placing a transistor circuit (Q3a, Q2a) in the feedback path such that it generates an offset voltage at the output of the operation amplifier, the voltage being the sum of the base-emitter voltages of the transistors of the circuit. Further, a second transistor circuit (Q3b, Q2b) is arranged at the output of the operation amplifier such that it generates a voltage at the output of the operation amplifier that compensates for the sum of the base-emitter voltages of the transistor circuit. The voltages thus cancel each other and the output offset voltage of the detector is zero. |
