US 8,175,535 B2 · Active cancellation of transmitter leakage in a wireless transceiver

Abstract

Active transmitter leakage cancellation techniques are disclosed, for reducing transmitter leakage in a frequency-duplexing radio transceiver. Reducing transmitter leakage to the receiver path of a duplex transceiver eases the linearity requirements for low-noise amplifier and mixer circuits, potentially reducing transceiver cost as well as complexity. In an exemplary method, a radio-frequency (RF) cancellation signal is generated from a transmitter signal, and the RF cancellation signal is combined with a received RF signal to obtain a combined RF signal comprising a residual transmitter leakage component. The residual transmitter leakage component of the combined RF signal is converted, using, e.g., a frequency mixer, to obtain a down-converted signal at baseband or at an intermediate frequency. A magnitude of the residual transmitter leakage component is detected from the down-converted signal, and used to adjust the phase or amplitude of the RF cancellation signal, or both, to reduce the residual transmitter leakage component.

Claims18

Dependent claims

A method of cancelling transmitter leakage in a primary receiver path of a frequency-duplexing transceiver, comprising:

generating a radio-frequency (RF) cancellation signal from a transmitter signal;
combining the RF cancellation signal with a received RF signal to obtain a combined RF signal comprising a residual transmitter leakage component;
converting, in a secondary receiver path, the residual transmitter leakage component of the combined RF signal to a down-converted signal by mixing, in the secondary path, the combined RF signal with a local oscillator signal at a first frequency where the transmitter signal is centered;
detecting, in the secondary receiver path, a magnitude of the residual transmitter leakage component from the down-converted signal;
obtaining a phase or amplitude adjustment, or both, based on the detected magnitude;
and
applying the phase or amplitude adjustment, or both, to the RF cancellation signal to reduce the residual transmitter leakage component.

4 more elements

A frequency-duplexing transceiver comprising:

a transmitter section configured to produce a transmitter signal at a first frequency;
a front-end section configured to combine a received radio-frequency (RF) signal with an RF cancellation signal to obtain a combined RF signal comprising a residual transmitter leakage component resulting from leakage to the front-end section from the transmitter section;
a frequency mixer coupled to the front-end section and configured to convert, in a secondary receiver path, the residual transmitter leakage component of the combined RF signal to a down-converted signal by mixing, in the secondary receiver path, the combined RF signal with a local oscillator signal at the first frequency;
a leakage detector section coupled to the frequency mixer and configured to detect, in the secondary receiver path, a magnitude of the residual transmitter leakage component from the down-converted signal;
and
a leakage cancellation section coupled to the leakage detector section, the transmitter section, and the front-end section, and configured to couple the transmitter signal from the transmitter to generate the RF cancellation signal, and to obtain a phase or amplitude adjustment, or both, based on the detected magnitude, and to apply the phase or amplitude adjustment, or both, to the RF cancellation signal, to reduce the residual transmitter leakage component in a primary receiver path.

3 more elements

Dependencies are inferred from the claim text.

Active cancellation of transmitter leakage in a wireless transceiver

Life of this patent

Active cancellation of transmitter leakage in a wireless transceiver

Life of this patent

Abstract

Claims18