06853690 is referenced by 86 patents and cites 78 patents.

A balanced transmitter up-converts a baseband signal directly from baseband-to-RF. The up-conversion process is sufficiently linear that no IF processing is required, even in communications applications that have stringent requirements on spectral growth. In operation, the balanced modulator sub-harmonically samples the baseband signal in a balanced and differential manner, resulting in harmonically rich signal. The harmonically rich signal contains multiple harmonic images that repeat at multiples of the sampling frequency, where each harmonic contains the necessary information to reconstruct the baseband signal. The differential sampling is performed according to a first and second control signals that are phase shifted with respect to each other. In embodiments of the invention, the control signals have pulse widths (or apertures) that operate to improve energy transfer to a desired harmonic in the harmonically rich signal. A bandpass filter can then be utilized to select the desired harmonic of interest from the harmonically rich signal. The sampling modules that perform the sampling can be configured in either a series or a shunt configuration. In embodiments of the invention, DC offset voltages are minimized between the sampling modules to minimize or prevent carrier insertion into the harmonic images.

Title
Method, system and apparatus for balanced frequency up-conversion of a baseband signal and 4-phase receiver and transceiver embodiments
Application Number
9/525615
Publication Number
6853690 (B1)
Application Date
March 14, 2000
Publication Date
February 8, 2005
Inventor
Michael W Rawlins
Lake Mary
FL, US
Gregory S Rawlins
Lake Mary
FL, US
Charley D Moses Jr
Jacksonville
FL, US
Richard C Looke
Jacksonville
FL, US
Robert W Cook
Switzerland
FL, US
Michael J Bultman
Jacksonville
FL, US
David F Sorrells
Jacksonville
FL, US
Agent
Sterne Kessler Goldstein & Fox PLLC
Assignee
ParkerVision
FL, US
IPC
H04L 027/20
H04L 027/12
H04L 027/04
View Original Source