Patent ID: 8406820

Claim:
In an accessory circuit for processing or influencing mobile radio signals received from or transmitted by a mobile radio terminal, a detection circuit, comprising: a detector unit for detecting a signal transmitted from a mobile radio terminal; the detection circuit forming a part of the accessory circuit and the accessory circuit, upon being prompted by said detector unit, adopting different operating states; said detector unit, upon detecting a transmitted signal from the mobile radio terminal, activating a circuit portion of the accessory circuit containing at least one transmission power amplifier for amplifying the transmitted signal, the power amplifier remaining deactivated in the absence of a transmitted signal from the mobile radio terminal; a switching means connected to and driven by said detector unit, said switching means being connected in a transmission path of the accessory circuit, on an input side of the at least one transmission power amplifier; a coupling element connected on an output side of the transmission power amplifier, wherein, at a start of a transmission burst of a signal transmitted by the mobile radio terminal, the signal is initially applied not to the transmission power amplifier but rather via said switching means to said detector unit, but wherein said detector unit changes over the transmitted signal detected thereby directly to the transmission power amplifier by operating said switching means; wherein, the detection circuit has a self-holding function, wherein said detector unit causes the accessory circuit to remain in an operating state intended for a presence of a transmitted signal, even after a changeover of said switching means, at least until the transmission power amplifier has turned on and a portion of the transmitted signal that is amplified and output by way of said coupling element connected to the output side of the transmission power amplifier is present at said detector unit.