Nxp B.v.

Epcos Ag

Christophe Chanlo

Adrianus Van Bezooijen

John Joseph Hug

Dmitry Pavlovich Prikhodko

Ronald Koster

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.

Circuit for detecting a magnitude and phase of an impedance of a load

The invention refers to a circuit and a method for detecting the impedance of a load, whereby the circuit and the method can be used by an impedance matching circuit. Impedance matching circuits need a complex algorithm to adjust the impedance accordingly. This algorithm renders the response time to be long. It has been found out that the complexity partially stems from the fact that the phase of the reflection coefficient is not known over the full range of 0&#xb0; to 360&#xb0;. A quadrature phase detector is used to provide the full phase information.

Circuit for detecting the impedance of a load

A method and circuit for preserving linearity of a RF power amplifier, the power amplifier including a RF power output unit () having a characteristic drive level and fed by a supply voltage, comprising measuring the output voltage of the RF power output unit (); comparing the measured output voltage to at least one threshold voltage to produce a control signal; and adapting the drive level or the supply voltage of the RF power output () unit by means of the control signal to operate the output unit below its saturation level. A method and circuit for stabilizing an antenna circuit comprising a RF power amplifier and a matching circuit by preserving linearity of a RF power amplifier, where the above power amplifier is used.

Preserving linearity of a rf power amplifier

A detection circuit for detecting the output power of a power amplifier comprises a first current minor transistor (Ti) having a base, which is connectable to a power transistor (T), and a collector, a RF detection means (RF-det) for detecting the RF current flowing through the current mirror transistor (T). Said RF detection means (RFdet) is connected to the collector of said first current mirror transistor (T). Said detection circuit further comprises a biasing means (bias-RF-det) for biasing said RF detection means (RF-det), wherein said biasing means is connected to said collector of said first current mirror (T) and said RF detection means (RF-det).

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Nijmegen, Netherlands

Christophe Chanlo