Abstract: Apparatus and method for rake receiving in a quadrature bandpass-sampling RF receiver is provided. The receiver bandpass-samples and quantizes an RF signal to provide an in-phase bi-level digital signal based on an in-phase clock and a quadrature bi-level digital signal based on a quadrature clock. The in-phase clock frequency and the quadrature clock frequency are equal to the RF signal carrier frequency. The quadrature clock is ninety degree out of phase with respect to the in-phase clock. The delayed bits in both the in-phase digital signal group and the quadrature digital signal group are maximal-ratio combined to provide diversity gain.

Abstract: A quadrature bandpass-sampling radio frequency (RF) receiver is provided. The receiver bandpass-samples and quantizes an RF signal to provide an in-phase bi-level digital signal based on an in-phase clock and a quadrature bi-level digital signal based on a quadrature clock. The in-phase clock frequency and the quadrature clock frequency are equal to the RF signal carrier frequency. The quadrature clock is ninety degree out of phase with respect to the in-phase clock.

Abstract: A calibration technique to compensate for the phase error between the in-phase and quadrature sampling clocks controlling the quadrature bandpass sampling delta-sigma analog-to-digital demodulator (QBS-ADD) is provided. A low-frequency test tone is injected, up-converted to the RF frequency, and added to an input of the QBS-ADD. The test tone is demodulated by the QBS-ADD into an in-phase signal and a quadrature signal. The in-phase and quadrature signals are filtered and multiplied together to generate a phase error signal, which is subsequently integrated to generate a phase shift control signal being used to correct the phase error between the in-phase and quadrature sampling clocks.

Abstract: A multi-channel quadrature bandpass-sampling receiver is provided with a plurality of RF signals that are modulated at different carrier frequencies, are frequency-shifted, and are staggered to a first IF frequency. A quadrature bandpass-sampling analog-to-digital demodulator digitizes and down-converts the aggregate RF signals to a second low IF frequency, wherein each frequency-shifted RF signal can be demodulated to DC by a digital down converter.

Abstract: Apparatuses for composing LC resonators in a continuous-time RF bandpass delta-sigma modulator are provided. A plurality of resonator inductors are shaped and strategically positioned on an integrated circuit die to minimize the resonant couplings. The resonator inductors can be also constructed from pairs of bond wires connected to a ground paddle, or to a set of lead frame pins. The inductance in each resonator can be increased by appending a specifically shaped planer inductor constructed from the PCB metal track to the bond wire pair via two lead frame pins.

Abstract: A calibration technique to compensate for the quadrature phase error between the in-phase and quadrature sampling clocks controlling the quadrature bandpass sampling delta-sigma analog-to-digital demodulator (QBS-ADD) is provided. A low-frequency test tone is injected in the feedback path, up-converted to the radio frequency (RF) frequency, and added to the input of the QBS-ADD. The test tone is demodulated by the QBS-ADD into an in-phase signal and a quadrature signal. The in-phase and quadrature signals are converted into the frequency domain by the discrete Fourier transform. The quadrature phase error is quantified based on the complex Fourier complex coefficients; and the phase difference between the in-phase and quadrature sampling clocks is corrected.

Abstract: A wide-frequency band quadrature bandpass-sampling receiver is provided. An RF signal received at the antenna is amplified by an LNA and filtered by an image-reject filter. The filtered RF signal is then frequency-shifted to an intermediate frequency which is located in between 1 GHz to 4 GHz. A quadrature bandpass-sampling analog-to-digital demodulator down-converts and digitizes the frequency-shifted signal at the intermediate frequency to baseband yielding a bi-level in-phase component and a bi-level quadrature component.

Abstract: A quadrature bandpass-sampling receiver providing time diversity for OFDM is provided. A quadrature bandpass-sampling analog-to-digital demodulator down converts an OFDM signal in the RF frequency range to baseband based on a high-frequency sampling clock equal to the RF frequency and generates the in-phase and quadrature outputs in form of high-frequency bit streams. The period of the bit stream is the inverse of the OFDM carrier frequency, which is much higher than the OFDM symbol rate, allows usage of multipath diversity to improve the communication link.

Abstract: A quadrature bandpass-sampling receiver for an orthogonal frequency division multiplexing (OFDM) receiver is provided. A transmitted OFDM signal is received by a low-noise amplifier, has its image frequency removed by a subsequent image reject filter, and is frequency-translated to an intermediate frequency by a mixer. A quadrature bandpass-sampling delta-sigma analog-to-digital demodulator (QBS-ADD) down-converts the frequency-translated OFDM signal to baseband based on a high-frequency sampling clock equal to the intermediate frequency, and generates in-phase and quadrature outputs in the form of high-frequency bit streams. The bit streams are fed to a Discrete Fourier Transform (DFT) engine, which generates in-phase and quadrature Fourier components.