Transformer-Loaded SSB Mixer for Wideband Frequency Selectivity
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Solution Overview
Problem
The complexity of local oscillator design in mobile communication systems increases due to various frequency bands, leading to a higher number of single side band (SSB) mixer blocks and circuit complications, which affects frequency selectivity.
Innovation Solution
A local oscillator incorporating an in-phase SSB mixer unit and a quadrature-phase SSB mixer unit with transformer loads, where the effective inductance of the primary loop is adjusted based on magnetic coupling, allowing for frequency synthesis across a wide frequency band without degrading frequency selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output frequency band of SSB mixer is reduced to cover various frequency bands, then the frequency band coverage is improved, but the number of SSB mixer blocks increases and circuit complexity increases
Solution Approach 1:
The SSB mixer is designed to perform multiple frequency synthesis functions across different frequency bands (e.g., LTE 700MHz, 1.8GHz, 2.1GHz, 2.6GHz, 3.5GHz, 5GHz) using a single mixer block. The mixer achieves universal frequency coverage by synthesizing multiple local oscillator signals simultaneously through its in-phase and quadrature-phase output paths, eliminating the need for separate mixers for each frequency band.
Solution Approach 2:
The SSB mixer employs dynamic frequency selection through selectively connectable first and second local oscillators. The system can dynamically switch between different oscillator combinations depending on the desired output frequency band, allowing a single mixer structure to adapt to various frequency requirements without requiring multiple dedicated mixer blocks for each band.
2Adaptability or versatility
If multiple SSB mixer blocks are used to cover various frequency bands, then the frequency band coverage is improved, but the local oscillator size increases
Solution Approach 1:
Multiple frequency synthesis functions that would traditionally require separate mixer blocks are merged into a single SSB mixer structure. The in-phase and quadrature-phase mixer units are combined with shared local oscillator inputs and output paths, consolidating what would have been multiple discrete components into one integrated local oscillator unit, thereby reducing overall size.
Solution Approach 2:
The single SSB mixer block is designed to universally support multiple frequency bands through its ability to synthesize different local oscillator frequencies and phases. This multi-functional design replaces what would traditionally require multiple specialized mixer blocks, significantly reducing the total volume of the local oscillator assembly while maintaining comprehensive frequency band coverage.
3Adaptability or versatility
If multiple SSB mixer blocks are used to cover various frequency bands, then the frequency band coverage is improved, but the circuit design becomes complicated and frequency selectivity degrades
Solution Approach 1:
The SSB mixer circuit is segmented into distinct in-phase and quadrature-phase mixer units, each handling specific signal paths. This segmentation allows for modular design and independent optimization of each path, simplifying the overall circuit design compared to trying to manage multiple full-featured mixer blocks. The segmented architecture also facilitates better frequency selectivity by allowing independent filtering and tuning of each path.
Solution Approach 2:
The circuit employs dynamic switching mechanisms that selectively connect different local oscillators to the mixer inputs based on the desired frequency band. This dynamic configuration reduces circuit complexity by activating only the necessary signal paths for the current operating frequency, rather than maintaining all possible frequency paths simultaneously. The dynamic switching also improves frequency selectivity by isolating active frequency paths from inactive ones.
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
Enables the use of SSB mixers in wide frequency bands without compromising frequency selectivity, simplifying the local oscillator design and reducing its size.
Implementation Method 1
An effective inductance of a primary loop of the first transformer may be changed based on a degree of a magnetic coupling between the primary loop of the first transformer and the secondary loop of the first transformer
Data Source
AI summary
A single side band (SSB) mixer includes an in-phase SSB mixer unit and a quadrature-phase SSB mixer unit. The in-phase SSB mixer unit generates an in-phase output current, and includes a first transformer load in which a portion of a quadrature-phase output current flows. The quadrature-phase SSB mixer unit generates the quadrature-phase output current, and includes a second transformer load in which a portion of the in-phase output current flows. The SSB mixer may be used in a wide frequency band without degrading frequency selectivity.