A pen for use with a touch screen includes a first AC coupling circuit, a second AC coupling circuit, a sense-regulation circuit, and a response circuit. The first AC coupling circuit receives a sense signal from the touch screen. The sense-regulation circuit compares the sense signal to a reference signal to produce a comparison signal. In addition, the sense-regulation circuit generates a regulation signal based on the comparison signal, which regulates receiving of the sense signal. The response circuit generates a transmit signal based on the comparison signal and data. The second AC coupling circuit transmits the transmit signal to the touch screen.