Abstract: A system and method are provided for compensating for an I/Q mismatch of either a direct conversion transmitter or a direct conversion receiver based on known short training symbols of a Short Training Sequence (STS) of packets transmitted according to the IEEE 802.11a or 802.11g standard. To compensate for an I/Q mismatch of a direct conversion transmitter, a packet including the STS is transmitted. Due to the I/Q mismatch of the direct conversion transmitter, the transmitter distorts the packet to provide a distorted packet including a distorted STS. Based on one or more short training symbols of the distorted STS and a known ideal short training symbol, a distortion matrix is determined. Subsequent packets transmitted by the direct conversion transmitter are pre-distorted based on the distortion matrix. Compensation of the I/Q mismatch of a direct conversion receiver may be performed in a similar fashion.

Abstract: A system and method are provided for calibrating for an I/Q mismatch of a direct conversion receiver based on a random signal having a two-dimensional I versus Q trajectory, such as radio frequency (RF) noise. In general, the random signal is received and downconverted to a quadrature baseband signal having an in-phase component and a quadrature component. The variance of the in-phase component, the variance of the quadrature component, and the covariance of the in-phase component with the quadrature component are computed based on samples of the quadrature baseband signal. A correction matrix used to compensate for the I/Q mismatch of the receiver and/or I/Q mismatch including a gain mismatch and a phase mismatch of the receiver is then computed based on the variance of the in-phase component, the variance of the quadrature component, and the covariance of the in-phase component with the quadrature component.

Abstract: A system and method are provided for compensating for an I/Q mismatch of either a direct conversion transmitter or a direct conversion receiver based on known short training symbols of a Short Training Sequence (STS) of packets transmitted according to the IEEE 802.11a or 802.11g standard. To compensate for an I/Q mismatch of a direct conversion transmitter, a packet including the STS is transmitted. Due to the I/Q mismatch of the direct conversion transmitter, the transmitter distorts the packet to provide a distorted packet including a distorted STS. Based on one or more short training symbols of the distorted STS and a known ideal short training symbol, a distortion matrix is determined. Subsequent packets transmitted by the direct conversion transmitter are pre-distorted based on the distortion matrix. Compensation of the I/Q mismatch of a direct conversion receiver may be performed in a similar fashion.

Abstract: A system and method are provided for compensating for an I/Q mismatch of a receiver in a mobile terminal. In general, the receiver and a transmitter of the mobile terminal are formed on a single substrate. A transmit signal is transmitted via the transmitter. Due to leakage through the substrate, the transmit signal is provided to one or more points in the receiver. One of these points is an input of the amplifier circuitry. A gain of the amplifier circuitry is modulated during reception of the transmit signal such that an amplified signal provided by the amplifier circuitry is offset from the carrier frequency of the transmit signal by a known frequency offset. The amplified signal is downconverted to provide a quadrature output signal. Processing circuitry processes frequency components of the quadrature output signal corresponding to the known frequency offset to determine the I/Q mismatch of the receiver.

Abstract: A method for measuring a difference in DC offsets associated with different gain settings in a direct conversion receiver having a variable gain is provided. In a first phase, a set of response parameters that characterize a time-dependent system response to a known change in the DC offset is determined. Each response parameter corresponds to the response measured at a different time after the change. In a second phase, different gain settings are applied to the system and the response is measured at times corresponding to the times associated with each of the response parameters. The response parameters are then used to determine the difference in DC offsets associated with the different gain settings.

Abstract: A behavioral model for mixed signal RF circuits. The model approximates non-linear filtering effects for base-band (i.e. suppressed carrier) end-to-end systems analysis. The new model, the K-model, is a linear MIMO (multi-input-multi-output) model with output radius corrected by a non-linear SISO (single-input-single output) model and output angle corrected by a non-linear rotation. The SISO model uses a multi-tanh structure to synthesize a non-linear filter. The multi-tanh structure simulates non-linear behavior by gently switching between transfer functions as the base-band input varies. For excursions well into the steady state non-linear region of operation the K-model simulates large-signal base-band transients to within about 10 percent of those simulated with detailed unsuppressed-carrier models.

Abstract: A method for measuring a difference in DC offsets associated with different gain settings in a direct conversion receiver having a variable gain is provided. In a first phase, a set of response parameters that characterize a time-dependent system response to a known change in the DC offset is determined. Each response parameter corresponds to the response measured at a different time after the change. In a second phase, different gain settings are applied to the system and the response is measured at times corresponding to the times associated with each of the response parameters. The response parameters are then used to determine the difference in DC offsets associated with the different gain settings.

Abstract: A behavioral model for mixed signal RF circuits. The model approximates non-linear filtering effects for base-band (i.e. suppressed carrier) end-to-end systems analysis. The new model, the K-model, is a linear MIMO (multi-input-multi-output) model with output radius corrected by a non-linear SISO (single-input-single output) model and output angle corrected by a non-linear rotation. The SISO model uses a multi-tanh structure to synthesize a non-linear filter. The multi-tanh structure simulates non-linear behavior by gently switching between transfer functions as the base-band input varies. For excursions well into the steady state non-linear region of operation the K-model simulates large-signal base-band transients to within about 10 percent of those simulated with detailed unsuppressed-carrier models.