IMPEDANCE DETECTOR

The invention relates to an antenna which is coupled to an RF amplifier. Environmental conditions change the impedance of the antenna, which reduces output power, efficiency and linearity. A circuit is provided which is designed to detect the impedance of the antenna. With the measured impedance, impedance matching can be accomplished. The circuit for detecting the impedance detects the signal travelling from the RF amplifier to the antenna, and measures the peak voltage and the peak current of this signal. Furthermore, the phase difference between the voltage and the current is measured. The advantage of the circuit is its compactness allowing for an easy integration on a chip. Furthermore, an impedance matching circuit is suggested which makes use of the above circuit for detecting the impedance.