Texas Instruments Corporation

Telefonaktiebolaget Lm Ericsson (Publ)

Charles Gore, Jr

Erik L Bengtsson

William O Camp, Jr

Abdellatif Bellaouar

David R Pehlke

Jeffrey A Schlang

Aristotle Hadjichristos

Scott R Justice

Sherif Embabi

Wing Kan Chan

Steven G Cairns

Jeff D Laster

Mohamed A I Mostafa

Moderage C Fernando

M Ali Khatibzadeh

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 digital signal processor generates in-phase, quadrature-phase and amplitude signals from a baseband signal. A modulator modulates the in-phase and quadrature-phase signals to produce a modulated signal. A phase locked loop is responsive to the modulated signal. The phase locked loop includes a controlled oscillator having a controlled oscillator input. An amplifier includes a signal input, amplitude control input and an output. The signal input is responsive to the controlled oscillator output and the amplitude control input is responsive to the amplitude signal. The in-phase and quadrature-phase signals may be normalized in-phase and quadrature-phase signals. Alternatively, a phase tracking subsystem may be provided that is responsive to the quadrature modulator to produce a phase signal that is responsive to phase changes in the modulated signal and that is independent of amplitude changes in the modulated signal. An amplitude tracking subsystem also may be provided that is responsive to the modulator to produce an amplitude system that is responsive to amplitude changes in the modulated signal and that is independent of the phase changes in the modulated signal. An amplifier has a signal output, an amplitude control input and an output. The signal input is responsive to the phase signal and the amplitude control input is responsive to the amplitude signal.

IQ modulation systems and methods that use separate phase and amplitude signal paths

Growing community of inventors

McKinney, TX, United States of America

Charles Gore, Jr