Patent ID: 8669805
Filing Date: 2014-03-11
Classification: H03K

Abstract:
1. A coupling circuit, comprising: a signal input; a signal output; a first and a second transistor, each of a p-channel field-effect transistor type, wherein a drain terminal of the first transistor is connected to the signal input, source terminals of the first and the second transistor are commonly connected to the signal output, bulk terminals of the first and the second transistor are commonly connected to a drain terminal of the second transistor, and a gate terminal of the first transistor is connected to a gate terminal of the second transistor; and a gate control circuit with a charge pump circuit which is configured to generate a negative potential, wherein the gate control circuit is configured to control a gate voltage at the gate terminals of the first and the second transistor based on the negative potential, wherein the gate control circuit comprises a separation circuit which is configured to actuate the first and the second transistor to a non-conducting state when a potential at the signal output falls below a reference potential.