Delta-Sigma Frequency Transposition for Linear RF Power Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing frequency transposition devices in radiofrequency communications, such as those used in mobile telephone applications, face challenges in achieving high amplification of low-power incident signals while preserving signal linearity, which is crucial for maintaining information integrity during the transposition process.
Innovation Solution
The integration of a delta-sigma modulation method that generates a binary signal for controlling the frequency transposition process, allowing the use of a periodic auxiliary signal with adjustable amplitude to manage the power of the transposed signal, thereby ensuring that the output signal power depends on both the incident signal and the auxiliary signal, and maintaining linearity without information loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional frequency transposition devices are used to amplify low-power incident signals, then the output signal power can be increased, but the signal linearity is degraded and information integrity is lost
Solution Approach 1:
The frequency transposition process is segmented into two independent stages: first, delta-sigma modulation converts the incident signal to a binary control signal that preserves linearity; second, this binary signal controls a switching mechanism that transposes the auxiliary carrier frequency while maintaining the original signal's linear characteristics. This segmentation allows power amplification without compromising linearity.
Solution Approach 2:
An auxiliary periodic signal (carrier) is introduced as an intermediary element. This auxiliary signal serves as a mediator that carries the transposed frequency information while the binary control signal maintains the linear relationship with the original incident signal. The auxiliary signal enables frequency transposition without directly affecting the linearity of the information-carrying signal.
2Power
If signal amplification is performed before frequency transposition, then the incident signal power is increased, but achieving high amplification while preserving linearity becomes particularly difficult
Solution Approach 1:
The conventional sequence of operations is inverted: instead of amplifying the incident signal first and then transposing, the invention first performs delta-sigma modulation to create a binary control signal, then uses this binary signal to control the frequency transposition of an auxiliary carrier. This inversion eliminates the need for complex linear amplification before transposition, as the binary switching mechanism inherently preserves linearity while providing the necessary power control.
3Adaptability or versatility
If the amplitude of the auxiliary signal is made variable, then the output signal power can be controlled over a wide range, but the device complexity increases
Solution Approach 1:
The invention changes the control parameter from continuous amplitude modulation to binary switching control. By varying the duty cycle or switching frequency of the binary control signal derived from delta-sigma modulation, the output power can be controlled over a wide range without requiring complex amplitude modulation circuits. This parameter transformation simplifies the device while maintaining adaptability.
Data Source
AI summary
A frequency transposition device including an input terminal for receiving an incident signal SI and a modulator of the one-bit delta-sigma type MDU connected to the input terminal. A generator MGN provides a periodic auxiliary signal SAX with a frequency equal to a desired transposition frequency. A frequency transposer of the Gilbert cell type has a signal input BES connected to the output of the generator, a control input BCO connected to the output of the delta-sigma modulator MDU, and an output BS delivering a transposed signal STR.