A circuit and method are provided. The method couples a first bias signal to a first internal node via a first resistor, couples a second bias signal to a second internal node via a second resistor, couples the first internal node to a ground node via a N-type switch, couples the second internal node to a power supply node via a P-type switch. The method further couples the first internal node to the second internal node via a transmission gate, couples a terminal to the first internal node via a first capacitor, and couples the terminal to the second internal node via a second capacitor.