Compact, low-power, high image rejection sideband separation receiver
Inventors
ZEINOLABEDINZADEH, Saeed • AL SERAGI, Ebrahim • Goldsmith, Paul
Assignees
California Institute of Technology • Arizona State University ASU • Arizona State University Downtown Phoenix campus
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Publication Number
US-12596081-B2
Publication Date
2026-04-07
Expiration Date
Abstract
A compact, low-power, high image rejection sideband separation receiver is provided. The receiver observes an input radio frequency (RF) signal of multiple spectral lines (spectral observation), then downconverts the signals to intermediate frequency (IF), and then separates the signals to be observed simultaneously in multiple channels. An embodiment is used to observe a signal (G-band) with two spectral lines and utilizes a two stage Weaver architecture to downconvert the signal's frequency, including a combination of mixers in the second stage that achieves the separation of two different channels.
Core Innovation
The invention relates to a sideband separation receiver and circuit that uses a two-stage Weaver image reject architecture with double quadrature downconversion to separate spectral-line components. The receiver operates on a plurality of radio frequency (RF) signals including a plurality of spectral lines and includes local oscillator phase combinations that produce an image rejection ratio.
The architecture downconverts the plurality of RF signals into first intermediate frequency (IF) signals and separates the first IF signals into a plurality of channels including two spectral lines. The invention further includes mixing and downconverting the first IF signals into second IF signals in which a first signal accumulates a same phase after the downconversion while a second signal creates out-of-phase signals at upper and lower channels.
The receiver preserves one of the signals and eliminates its counterpart by summing the upper and lower channels for preserving the first signal and eliminating the second signal, and by differencing the upper and lower channels for preserving the second signal at the image frequency while eliminating the first signal. Separating the first signal from the second signal is achieved by manipulating a phase and amplitude of the two spectral lines, thereby enabling observing the first signal without the second signal and producing chemical spectral information.
In addition to the receiver method and circuit, the invention also provides a method and system for detecting content of a sample based on emitted spectral lines. The sample is excited by transmitting a source signal of known frequency, and the sample emits a sample signal based on the source signal. The emitted sample signal including a plurality of spectral lines is processed through the same sideband separation stages so that the receiver can detect chemical spectral information from the preserved first signal, and the document further characterizes the content including molecular content and isotopic abundance.
Claims Coverage
The partial content includes four independent claims: clm-00001, clm-00010, clm-00015, and clm-00020. Across these independent claims, the key inventive features are centered on multi-stage downconversion to IF signals, channel separation using pre-selected phase combinations to produce an image rejection ratio, and preserving one resulting frequency while eliminating the image frequency by manipulating phase and amplitude and applying sum/difference operations across upper and lower channels.
Multi-stage downconversion with channel separation and image rejection ratio
receiving a plurality of radio frequency (RF) signals including a plurality of spectral lines; mixing and downconverting the plurality of RF signals to first intermediate frequency (IF) signals; separating the first IF signals into a plurality of channels, the plurality of channels including two spectral lines and an image rejection ratio produced by pre-selected phase combinations
Phase-conditioned second IF signals with upper/lower out-of-phase behavior
mixing and downconverting the first IF signals into second IF signals, wherein a first signal of the second IF signals accumulates a same phase after the downconversion and a second signal of the second IF signals creates out-of-phase signals at upper and lower channels of the first signal
Sum and difference combining to preserve desired frequency and eliminate its image
preserving the first signal and eliminating the second signal by summing the upper and lower channels; preserving the second signal located at the image frequency of the first signal and eliminating the first signal by differencing the upper and lower channels; separating the first signal from the second signal by manipulating a phase and amplitude of the two spectral lines, wherein the separating enables observing the first signal without the second signal
Transmitter-driven emitted spectral-line content detection
transmitting a source signal of known frequency, the source signal being received by the sample, the sample emitting a sample signal based on the source signal; receiving the sample signal including a plurality of spectral lines; detecting the content of the sample based on the first signal plurality of channels
Three-stage circuit with computed resulting frequencies via sum and difference
a first stage configured to receive a radio frequency (RF) signal, the first stage configured to produce two first intermediate frequency (IF) signals; a second stage configured to receive the two first IF signals, the second stage configured to produce two second IF signals; and a third stage configured to compute two resulting frequencies based on a sum and a difference between the two second IF signals, wherein the sum preserves the first of the resulting frequencies and eliminates a second of the resulting frequencies, the second of the resulting frequencies being located at the image frequency of the first of the resulting frequencies, the difference eliminates the first of the resulting frequencies
Across the independent claims, the invention is directed to multi-stage sideband separation that uses pre-selected phase combinations to produce an image rejection ratio, forms phase-conditioned second IF signals with upper/lower out-of-phase behavior, and then applies sum and difference operations (and in a circuit computes resulting frequencies from sums and differences) to preserve a desired frequency while eliminating its image. The preserved first signal is then used for detecting chemical spectral information and, in content-detection embodiments, for detecting the content of a sample based on emitted spectral lines.
Stated Advantages
Enables observing the first signal without the second signal.
Produces an image rejection ratio by pre-selected phase combinations.
Separating allows chemical spectral information to be detected from the first signal.
Enables detecting the content of a sample based on the first signal plurality of channels.
Detects molecular content and isotopic abundance [stated in dependent claims].
Documented Applications
Detecting chemical spectral information from a preserved first signal derived from separated frequency components.
Detecting content of a sample based on emitted spectral lines, where the receiver processes emitted spectral information to produce content detection based on the first signal plurality of channels.
Detecting molecular content and isotopic abundance from spectral observations delivered through the receiver channels [dependent claim context].
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