METHOD AND APPARATUS FOR DETECTING A TOUCH ON A DEVICE

摘要

A method and circuitry for detecting a touch on a device is provided herein. Touch-sensing circuitry comprises two antennas (106, 107) coupled to two voltage-controlled oscillators VCOs (101, 102). A phase locked loop PLL (103) is provided coupled to the VCOs. The PLL compares a VCO output with a frequency source of a temperature controlled crystal oscillator TCXO (105), and outputs a tuning voltage (steering voltage) for the VCO that is based on the difference between the VCO frequency and the TCXO frequency. The steering voltages for each VCO are compared, and a decision is made as to whether or not a touch has been made to the antennas. If the antennas have been touched, a location of the touch is determined based on a difference in the steering voltages of the two VCOs.