Embodiments of the present disclosure utilizes the natural properties of RFI noise on a wireline link. Since differential RFI noise in the system has some correlation with the common mode noise on the cable, a replica of RFI noise can be regenerated by an adaptive filter based on information about the common mode noise. The replica RFI is subtracted from the equalizer output prior to the data decision circuitry or slicer. In this method, the system does not require expensive cable, nor does the equalizer suffer additional loss due to an RFI notch filter. Since RFI can be detected and mitigated, this information can also be coupled to safety systems to increase functional safety under high EMI conditions.

A receiver includes a switch network, a mixer, and an IQ mismatch (IQMM) estimation circuit. The switch network is adapted to be coupled to an output of a transmitter. The switch network is configured to selectably swap complementary signals of a differential pair. The mixer is coupled to the switch network and is configured to down-convert an output signal of the switch network. The IQ IQMM estimation circuit is coupled to the mixer, and is configured to estimate an IQMM of the transmitter based on an output signal of the mixer.

A receiver includes a switch network, a mixer, and an IQ mismatch (IQMM) estimation circuit. The switch network is adapted to be coupled to an output of a transmitter. The switch network is configured to selectably swap complementary signals of a differential pair. The mixer is coupled to the switch network and is configured to down-convert an output signal of the switch network. The IQ IQMM estimation circuit is coupled to the mixer, and is configured to estimate an IQMM of the transmitter based on an output signal of the mixer.

A noise cancellation system comprises an I-channel mixer configured to receive a radio frequency signal from an antenna and an intermediate frequency signal from a local oscillator, a Q-channel mixer configured to receive the radio frequency signal from the antenna and a phase-shifted intermediate frequency signal from the local oscillator, a first noise cancellation apparatus connected with the I-channel mixer, wherein an I-channel differential mode second-order intermodulation component and an I-channel common mode second-order intermodulation component cancel each other in the first noise cancellation apparatus and a second noise cancellation apparatus connected with the Q-channel mixer, wherein a Q-channel differential mode second-order intermodulation component and a Q-channel common mode second-order intermodulation component cancel each other in the second noise cancellation apparatus.

A noise cancellation system comprises an I-channel mixer configured to receive a radio frequency signal from an antenna and an intermediate frequency signal from a local oscillator, a Q-channel mixer configured to receive the radio frequency signal from the antenna and a phase-shifted intermediate frequency signal from the local oscillator, a first noise cancellation apparatus connected with the I-channel mixer, wherein an I-channel differential mode second-order intermodulation component and an I-channel common mode second-order intermodulation component cancel each other in the first noise cancellation apparatus and a second noise cancellation apparatus connected with the Q-channel mixer, wherein a Q-channel differential mode second-order intermodulation component and a Q-channel common mode second-order intermodulation component cancel each other in the second noise cancellation apparatus.

System and methods are provided for calibration of low pass filter mismatch. An example system includes: a tone generator configured to generate a tone signal with a baseband frequency value; one or more low pass filters configured to filter one or more analog signals associated with the tone signal; one or more analog-to-digital converters (ADCs) configured to generate one or more aliases associated with the one or more analog signals; and a calibration processor configured to detect low pass filter mismatch based at least in part on the one or more aliases associated with the tone signal.

An AGC circuit for a radio receiver includes a detector converting a high frequency signal into a baseband signal. To reduce generation of a DC offset, the AGC circuit includes: a variable gain amplifier having an amplifier circuit and a high-pass filter, the amplifier circuit amplifying the baseband signal with a variable gain and the high-pass filter coupled to the amplifier circuit and having a cut-off frequency which is variable; a controller supplying a gain control signal; and a blocker temporarily blocking the high frequency signal. Using the block control signal, the controller causes the blocker to start blocking the high frequency signal, before the cut-off frequency of the high-pass filter is switched from high to low.

A quadrature detection unit subjects an FM signal to quadrature detection using a local oscillation signal and outputs a base band signal. A first correction unit and a second correction unit correct the base band signal using a DC offset correction value. A DC offset detection unit subjects the corrected base band signal to rectangular to polar conversion and derives the DC offset correction value such that amplitudes in a plurality of phase domains defined in an IQ plane approximate each other. An FM detection unit subjects the corrected base band signal to FM detection and generates a detection signal. An addition unit adds an offset to the detection signal. An AFC unit generates a control signal for controlling a frequency of a local oscillation signal based on the detection signal to which the offset is added.

A quadrature detection unit subjects an FM signal to quadrature detection using a local oscillation signal and outputs a base band signal. A first correction unit and a second correction unit correct the base band signal using a DC offset correction value. A DC offset detection unit subjects the corrected base band signal to rectangular to polar conversion and derives the DC offset correction value such that amplitudes in a plurality of phase domains defined in an IQ plane approximate each other. An FM detection unit subjects the corrected base band signal to FM detection and generates a detection signal. An addition unit adds an offset to the detection signal. An AFC unit generates a control signal for controlling a frequency of a local oscillation signal based on the detection signal to which the offset is added.

A first local oscillator generates a modulation signal of a predetermined frequency. A second local oscillator outputs a local oscillation signal frequency-modulated by using the modulation signal from the first local oscillator. A quadrature detection unit subjects an FM signal to quadrature detection by using the local oscillation signal output from the second local oscillator and outputs a base band signal. A first reduction unit and a second reduction unit reduce a direct current component contained in the base band signal. A correction unit restores the direct current component by correcting the base band signal such that the base band signal is centered around an origin of a polar coordinate system on an IQ plane. An FM detection unit subjects the corrected base band signal to FM detection and generates a detection signal.