Polyphase Mixer Translational Filtering for Multi-Band RF Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF circuits face challenges in achieving high sensitivity for multiple bands due to parasitic reactive impedances, which can block desired bands and introduce negative frequency impedance responses, leading to unwanted signal reception.
Innovation Solution
A radio frequency (RF) circuit with a polyphase reactive circuit and two mixer circuits is used to adjust the input impedance response to compensate for parasitic impedances and reject negative frequency responses. The first mixer circuit downconverts RF signals to intermediate or baseband frequencies, and the second mixer circuit further adjusts the frequency offset using a second oscillation frequency to center the impedance image on the desired band, rejecting negative frequency responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single receiver circuit is used to receive multiple bands, then device complexity is reduced, but sensitivity for all bands cannot be maintained due to parasitic reactive impedances
Solution Approach 1:
The patent changes the frequency parameter by using a mixer to translate the reactive circuit impedance response from baseband to RF frequencies. By varying the oscillation frequency of the mixer, the same receiver circuit can be tuned to different bands, maintaining sensitivity across multiple frequencies without requiring multiple dedicated receiver circuits.
Solution Approach 2:
The patent makes a single receiver circuit universal by combining it with a mixer and reactive circuit that can be frequency-translated. The same receiver circuit serves multiple bands through frequency translation, eliminating the need for separate receiver circuits for each band while maintaining the sensitivity characteristics of a dedicated circuit for each frequency.
2Reliability
If translational filtering is used to achieve high-Q filter response, then sensitivity is improved, but parasitic reactive impedances cause frequency offset errors that block desired bands
Solution Approach 1:
The patent uses feedback by monitoring the actual frequency response and adjusting the mixer oscillation frequency to compensate for errors caused by parasitic reactive impedances. This feedback mechanism ensures that the desired band is correctly positioned at the expected frequency despite the presence of parasitic elements that would otherwise cause frequency offset errors.
3Reliability
If reactive circuit impedance response is translated to RF frequencies, then filtering performance is improved, but negative frequency impedance responses are also translated causing unwanted signal reception
Solution Approach 1:
The patent extracts only the desired positive frequency impedance response from the translated spectrum while rejecting the unwanted negative frequency response. This is achieved through careful design of the mixer and reactive circuit configuration that allows selective translation and filtering of the desired frequency components while excluding the harmful negative frequency images.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The RF circuit provides a high-Q impedance response, effectively filtering out unwanted signals and ensuring that the desired band is received with improved sensitivity, even in the presence of parasitic impedances, by accurately adjusting the frequency offset and rejecting negative frequency responses.
Implementation Method 1
a first mixer circuit and a second mixer circuit. The first mixer circuit may be connected to receive an input signal that is associated with the RF signal from the source. The first mixer circuit may provide the input impedance response and present an input impedance in accordance with the input impedance response to the source.
Implementation Method 2
The second mixer circuit is operable to mix the first in-phase signal and the first quadrature phase signal with four oscillation signals, all operating at approximately a second oscillation frequency, to generate a second in-phase signal and a second quadrature phase signal
Data Source
AI summary
Embodiments of a radio frequency (RF) circuit provide translational filtering in accordance with an input impedance response that is an impedance image of a reactive circuit impedance response from a poly phase reactive circuit. The RF circuit may include a first mixer circuit that provides a first frequency offset for the impedance image and a second mixer circuit that provides an additional frequency offset. Accordingly, the second mixer circuit may allow for adjustments to a total frequency offset of the impedance image. The second mixer circuit may also be configured so that the impedance image rejects a negative frequency impedance response of the reactive circuit impedance response.