An electronic circuit (12, 12′) for a reader device (10, 10′) for contactless communication with a transponder (20) is disclosed. The electronic circuit (12, 12′) comprises a connection (13a, 13b) to an antenna (11) of said reader device (10, 10′), which antenna (11) is designed for receiving a radio signal (TRS) from said transponder (20). Furthermore, it comprises a receiving module (14), which is connected to the antenna connection (13a, 13b) and arranged for processing an input voltage (VI) from said antenna (11) representing said radio signal (TRS). To provide satisfactory operation of the receiving module (14) and to compensate a bad matching of the antenna circuit to the electronic circuit (12, 12′) and/or bad environmental conditions where the reader device (10, 10′) is operated, the electronic circuit furthermore comprises a control module (15, 15′). Said control module (15, 15′) is arranged to compare said input voltage (VI) to a reference value (VR) and to adjust a plant of said reader device (10, 10′) in such a manner that the level of said input voltage (VI) stays in a predefined range. The invention furthermore relates to a reader device (10, 10′) and a method of operating a reader device (10, 10′).