A coupling circuit has a first and a second transistor (P1, P2) of a p-channel field-effect transistor type. A drain terminal of the first transistor (P1) is connected to a signal input (1), source terminals of the first and the second transistor (P1, P2) are commonly connected to a signal output (2), bulk terminals of the first and the second transistor (P1, P2) are commonly connected to a drain terminal of the second transistor (P2), and a gate terminal of the first transistor (P1) is connected to a gate terminal of the second transistor (P2). The coupling circuit further comprises a gate control circuit (10) with a charge pump circuit (110) which is configured to generate a negative potential. The gate control circuit (10) is configured to control a gate voltage at the gate terminals of the first and the second transistor (P1, P2) based on a negative potential.