Texas Instruments Corporation

Wing Kan Chan

Joseph T Nabicht

Sherif Embabi

Charles Gore, Jr

Mohamed A I Mostafa

Moderage C Fernando

Mohamed A Mostafa

A subsampling receiver () for converting an RF signal to baseband is disclosed. The subsampling receiver () may be implemented into a wireless communications device (), such as a wireless telephone handset. In one disclosed embodiment, the receiver () includes a sample and hold circuit () that samples a bandpass filtered input modulated signal at the subsampling frequency (f) that is well below the RF carrier frequency but twice the bandwidth (BW) of the payload; the sampled signal is digitized, and applied to two digital mixers (I,Q) to produce in-phase and quadrature components (I,Q) of the payload. In another embodiment, the receiver () includes two sample and hold circuits (I,Q) to sample the filtered signal at different phases of the sampling frequency, to produce the in-phase and quadrature digital components. In a third embodiment, the receiver () includes an analog mixer () to downconvert the RF input to an intermediate frequency, prior to digitization and digital mixing at quadrature phase.

Subsampling RF receiver architecture

A technique for implementing impedance matching circuitsthat use the transfer functions of each line impedance model. This technique allows implementation of an impedance match for a diverse number of line impedances reusing the same circuittopology, by simply adjusting coefficients to accommodate different line impedances.

Generic line impedance matching circuit using decomposed configurable transfer functions

A simple, power efficient and inexpensive digital compensation scheme for reducing delay in a digital impedance matching circuit to improve return loss. The scheme employs a digital filter to compensate for the absolute sampling and digital delays associated with a digital impedance matching circuit. The digital filter is based on the low-pass function of a DAC response, and can easily be modified to correct for not only the DAC response delay, but also other delays in the digital impedance matching circuit. The digital filter is very simple to implement and can add or subtract delays from the overall system.

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Allen, TX, United States of America

Wing Kan Chan