Switching regulator, transceiver circuit, and keyless access control system

A transceiver circuit for a device for inductive data transmission or a device for a keyless access control system in or for a vehicle, the transceiver circuit comprising:

• at least one antenna resonant circuit for wireless transmission of transmit signals;
• and
• at least one switching regulator to regulate an antenna potential so that the antenna current flowing through the antenna resonant circuit moves back and forth in a zigzag fashion between a preset lower threshold value and a preset upper threshold value, the switching regulator comprising:
• an input terminal into which an antenna potential applied or appliable at the transmit antenna is coupled;
• and
• a control circuit for generating a compensation signal as a controlled variable for adapting the antenna potential to an actual output impedance and to establish a slope of a compensation signal depending on an actual antenna potential.

A keyless access control system in or for a vehicle, the system comprising:

• at least one vehicle-side antenna circuit;
• at least one vehicle-side transceiver circuit that is connected to the antenna circuit via respective connection lines to control the antenna circuit;
• and
• at least one transponder for communicating via data communication upon approach to the vehicle-side transceiver circuit, the transceiver circuit comprising:
• at least one antenna resonant circuit for wireless transmission of transmit signals;
• and
• at least one switching regulator to regulate an antenna potential so that the antenna current flowing through the antenna resonant circuit moves back and forth in a zigzag fashion between a preset lower threshold value and a preset upper threshold value, the switching regulator comprising:
• an input terminal into which an antenna potential applied or appliable at the transmit antenna is coupled;
• and
• a control circuit for generating a compensation signal as a controlled variable for adapting the antenna potential to an actual output impedance and to establish a slope of a compensation signal depending on an actual antenna potential