CHANNELIZED ACTIVE NOISE ELIMINATION (CANE) FOR BIT STREAM RF TRANSMITTERS

摘要

A band pass filter is implemented utilizing Channelized Active Noise Elimination (CANE) in combining Finite Impulse Response (FIR) filtering into a radio frequency (RF) transmitter, or transmission path. The FIR filtering is performed in a combination of multiple conversion paths of delay units, vector modulators and PAs so that the low pass characteristics of the FIR filter are upconverted on the adjacent frequency of the carrier to form a band pass filter at the output of the transmitter. Use of CANE avoids the need of high sampling rates, while also eliminating the need of either broad bandwidth delay lines or modulated power amplifiers. The technique is well-suited for suppression of the quantization noise generated in RF transmitters with bitstream modulations such as the Envelope Delta Sigma Modulation (EDSM).

主权项

1. An apparatus for band pass filtering with channelized active noise elimination, the apparatus comprising:
(a) a baseband transmitter configured for generating a complex baseband signal; (b) a bitstream modulation circuit coupled to said baseband transmitter for receiving said complex baseband signal; (c) a circuit for generating a complex digitized envelope; and (d) a digital-to-analog converter having finite impulse response (FIR) filtering based on power combining and configured with multiple conversion paths with outputs combined at a signal combiner, which outputs an radio-frequency (RF) signal; (e) wherein each conversion path of said multiple conversion paths comprises a series combination of a delay-line, a vector modulator, and a power amplifier, with the combination configured for channelized noise elimination, and with low pass characteristics of said FIR filtering used with an upconverted carrier to form a band pass filter.