Patent ID: 7190220

Claim:
A circuit for providing a base operating voltage for a bipolar transistor, comprising: a base-emitter voltage multiplier with a multiplier transistor operable to provide a working voltage as a reaction to a working-point control current at a working point control current terminal, wherein the working voltage is equal to a base-emitter voltage drop of the multiplier transistor multiplied by a voltage amplification factor; the multiplier transistor including a base, an emitter, and a collector, wherein the working voltage is provided at the collector, wherein the emitter is connected to a reference potential, and wherein the base is connected to an intermediate node; the base-emitter voltage multiplier further comprising a first splitter resistor between the intermediate node and the collector of the multiplier transistor; and a second splitter resistor between the intermediate node and the reference potential; and a circuit operable to reduce the working voltage to a base operating voltage for a bipolar transistor, which base operating voltage is smaller than a base-emitter voltage drop of the bipolar transistor, wherein the circuit operable to reduce the working voltage to the base operating voltage comprises an emitter follower transistor operable to buffer the working voltage and operable to reduce the working voltage by a base-emitter voltage drop of the emitter follower transistor, wherein the working point control current terminal is connected to the collector of the multiplier transistor and is furthermore connected to a base of the emitter follower transistor, and wherein the first splitter resistor and the second splitter resistor are selected such that the voltage amplification factor is greater than or equal to 1.4 and less than or equal to 2.