Frequency Converter LO Signal Harmonic Elimination
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Solution Overview
Problem
Existing software-defined radio receivers face challenges in suppressing crosstalk between interference signals, particularly harmonics of the local oscillation (LO) signal and the received signal, while minimizing circuit size and power consumption, especially when dealing with varying radio communication standards.
Innovation Solution
A frequency converter with an LO signal generator capable of varying phase resolution is used, which multiplies the received signal with an LO signal to convert its frequency, eliminating harmonics of the LO signal within the usable bandwidth without the need for an RF tracking filter or multiple band pass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a square wave LO signal is used for frequency conversion, then circuit area and power consumption are reduced, but crosstalk between harmonics of the LO signal and the received signal increases
Solution Approach 1:
The invention applies preliminary action by eliminating harmful harmonic components from the LO signal before frequency conversion. The harmonic elimination circuit removes odd-order harmonics (3rd, 5th, 7th, etc.) from the square wave LO signal in advance, preventing these harmonics from causing crosstalk with the received signal during the mixing process.
Solution Approach 2:
The invention converts the harmful effect of harmonics into a benefit by using the harmonic elimination circuit to selectively remove only the harmful odd-order harmonics while preserving the fundamental frequency and even-order harmonics. This selective filtering transforms the problematic square wave signal into a beneficial waveform that maintains the advantages of square wave generation (low power, small area) while eliminating its harmful harmonic content.
2Object-generated harmful factors
If multiple band pass filters are used to eliminate interference signals, then crosstalk is reduced, but device complexity and circuit area increase
Solution Approach 1:
The invention merges the function of multiple band pass filters into a single harmonic elimination circuit. Instead of using separate filters for each harmonic frequency (3rd, 5th, 7th, etc.), the harmonic elimination circuit performs all harmonic rejection functions in one integrated component, significantly reducing device complexity and circuit area while maintaining effective crosstalk suppression.
Solution Approach 2:
The harmonic elimination circuit serves multiple functions simultaneously: it eliminates 3rd-order harmonics, 5th-order harmonics, 7th-order harmonics, and other odd-order harmonics from the LO signal. This multi-functional approach replaces what would traditionally require multiple specialized filters, each targeting a specific harmonic frequency.
3Object-generated harmful factors
If an RF tracking filter is used to eliminate high-frequency interference signals, then crosstalk is reduced, but device complexity and power consumption increase
Solution Approach 1:
The invention extracts and eliminates the harmful harmonic components directly from the LO signal source using the harmonic elimination circuit. By removing the 3rd, 5th, 7th, and other odd-order harmonics at their source, the system eliminates the need for additional RF tracking filters that would be required to suppress these harmonics later in the signal path, thereby reducing power consumption.
4Adaptability or versatility
If the pass bandwidth of a band pass filter is made variable to handle multiple radio standards, then adaptability is improved, but manufacturing precision and filter design become more difficult
Solution Approach 1:
The invention applies dynamics by making the LO signal characteristics adaptable rather than fixed. The harmonic elimination circuit dynamically adjusts which harmonic components are removed based on the operating frequency and radio standard being used. This dynamic approach allows the system to maintain optimal performance across multiple radio standards without requiring multiple fixed-bandwidth filters.
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
This approach effectively reduces crosstalk between interference signals and the received signal, minimizing circuit size and power consumption, and allows for efficient frequency conversion across a wide range of frequencies without the need for additional filters.
Implementation Method 1
a mixer that multiplies a received signal that has been band-limited to a usable bandwidth of said receiver by the LO signal so as to convert the frequency of the received signal
Data Source
AI summary
The present invention is applied to a frequency converter used for a receiver. The frequency converter according to the present invention includes an LO signal generator (11) that generates an LO signal and outputs the LO signal; and a mixer (10) that multiplies a received signal that has been band-limited to a usable bandwidth of said receiver by the LO signal so as to convert the frequency of the received signal and outputs the resultant signal. Said LO signal generator is capable of varying a phase resolution.