公开(公告)号：AT411648T

公开(公告)日：2008-10-15

申请号：AT99938835

申请日：1999-07-27

Applicant: QUALCOMM INC

Inventor： BUTTERFIELD DANIEL

IPC: H03M3/02 ,  H04B1/00 ,  H03F3/24 ,  H04B1/38 ,  H04B1/40 ,  H04L27/00

Abstract: A hardware-efficient transceiver. The transceiver includes a digital circuit for converting baseband signals to intermediate frequency signals. A signal source provides a first periodic signal of a first frequency. A direct digital synthesizer provides a second periodic signal of a second frequency from the first periodic reference signal. An upconverter circuit digitally upconverts the baseband signals to digital intermediate frequency signals using the second periodic signal A digital-to-analog converter converts the digital intermediate frequency signals to analog intermediate frequency signals using the first periodic signal. In the transceiver implementation, the digital circuit upconverts a first transmit signal from a first frequency to a second frequency in response to the second periodic signal and provides a digital transmit signal in response thereto. A second circuit is provided for converting the digital transmit signal to an analog transmit signal. Transmit and receive circuitry are provided for transmitting the analog transmit signal and receiving an analog receive signal, respectively. In a specific embodiment, the analog receive signal is digitally downconverted to provide a digital receive signal in response to a second periodic signal. A significant feature of the invention resides in the provision of the first and second periodic signals with a single local oscillator. A direct digital synthesizer is included for generating one of the reference signals from the output of the local oscillator. The transmit circuit includes a delta-sigma digital-to-analog converter having the first periodic signal as an input The delta-sigma digital-to-analog converter has a low-bit digital-to-analog converter and a delta-sigma modulator. In the illustrative embodiment, the low-bit digital-to-analog converter is a 1-bit digital-to-analog converter and the delta-sigma modulator is a sixth order delta-sigma modulator. The delta-sigma modulator includes amplifiers with approximately the following gains: 3/2, -3/4, 1/8.

公开(公告)号：SG11202009219QA

公开(公告)日：2020-11-27

申请号：SG11202009219Q

申请日：2019-03-18

Applicant: QUALCOMM INC

Inventor： SUN BO ,  TANG YI ,  BUTTERFIELD DANIEL

IPC: H03K3/011 ,  H03K5/131

Abstract: Aspects generally relate to reducing delay, or phase jitter, in high speed signals transmission. Variations in power supply to ground potential changes the amount of delay introduced by transmit circuitry into the signal being transmitted, resulting in jitter, or phase noise, in the transmitted signal. To reduce phase jitter, or phase noise, aspects disclosed include a variable impedance circuit coupled to the signal distribution network, the impedance level of the variable impedance circuit is adjusted in response to variation in the supply to ground potential, such that the delay introduced by the impedance compensates for changes in the delay due to variations in supply to ground potential, resulting in substantially constant delay.