Embodiments of RFID tag circuits and methods are described, which include a chip having a clock circuit operable to generate a clock signal having different frequencies, and one or more components operable to work at the different frequencies. In addition to a regular frequency, at least one higher frequency is possible, which is enabled in situations where a reader is known to be close to the chip. The proximity ensures that the chip generates reliably more power, which enables its operation at the higher speed.