Patent ID: 7787851

Claim:
A circuit arrangement with a radio-frequency mixer comprising: the radio-frequency mixer having a first input, a second input, and an output; a first preamplifier having an input and an output; a first switching mechanism that turns on and off the first preamplifier; a second preamplifier having an input and an output; a common output node connected concurrently to the output of the first preamplifier and the output of the second preamplifier; and a second switching mechanism that turns on and off the second preamplifier; wherein the common output node is coupled to the first input of the radio-frequency mixer and also receives a supply voltage; wherein the second preamplifier comprises a common-emitter transistor, with a base connection connected to the input, with a collector connection connected to the common output node, and with an emitter connection coupled to a reference potential connection; wherein the second switching mechanism is in the form of a switch with a first connection coupled to the base connection of the common-emitter transistor and a second connection coupled to the emitter connection of the common-emitter transistor.