Analog Baseband Filter Switching for Multiband Cutoff Accuracy
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Solution Overview
Problem
Multimode multiband radio transceivers face challenges in accurately configuring cutoff frequencies for analog baseband filters due to variations in resistance and capacitance with temperature and process conditions, leading to increased circuit area and manufacturing costs, as well as signal degradation and noise issues.
Innovation Solution
A filtering apparatus for a multimode multiband radio transceiver that includes a filtering unit, a switching unit, and a controller to switch among multiple filter blocks based on selected communication modes, allowing for variable gain amplification and frequency filtering across various frequency bands, while sharing capacitors and resistors to minimize circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large capacitance values are used to process low band signals, then the cutoff frequency accuracy is improved, but the circuit area increases significantly
Solution Approach 1:
The patent changes the resistance parameter dynamically using a switching unit that selects between different resistance values (first resistance for high band, second resistance for low band) based on the operating mode. This allows the circuit to achieve accurate cutoff frequencies for both 3G/4G and 2G modes without requiring large capacitance values, thereby avoiding increased circuit area.
Solution Approach 2:
The patent introduces dynamic switching between different resistance configurations based on the communication mode (3G/4G or 2G). The switching unit dynamically adjusts the resistance value in the feedback path of the integrator, enabling the same capacitor to serve multiple bandwidth requirements without physical size changes.
2Measurement precision
If separate capacitors are provided for 2G and 3G/4G modes, then the cutoff frequency control is improved, but the manufacturing cost increases
Solution Approach 1:
The patent makes the capacitor universal by using the same capacitor for both 3G/4G and 2G modes. The differentiation between modes is achieved through switching resistance values rather than using separate capacitors. This multi-functional approach reduces component count and manufacturing complexity while maintaining precise cutoff frequency control for different communication standards.
Solution Approach 2:
The patent merges the capacitor resource between 2G and 3G/4G modes, allowing a single capacitor to serve both purposes. The switching unit combines the control logic for different modes, enabling one capacitor to be used in conjunction with different resistance values to achieve the required cutoff frequencies for various communication standards.
3Adaptability or versatility
If the circuit area is increased to support legacy 2G mode, then the bandwidth coverage is improved, but the signal quality degrades due to longer wire length
Solution Approach 1:
The patent uses dynamic switching to activate only the necessary circuit components for the current communication mode. When operating in 2G mode, the switching unit connects the low band resistance path; when in 3G/4G mode, it connects the high band resistance path. This dynamic reconfiguration maintains signal integrity by minimizing active wire length and component count for each mode, reducing noise and signal degradation.
Solution Approach 2:
The patent optimizes the circuit for local requirements of each communication mode by providing different resistance values tailored to specific bandwidth needs. The switching unit enables the circuit to have locally optimized characteristics (high resistance for 3G/4G, low resistance for 2G) without requiring a globally oversized design, thereby maintaining signal quality while achieving broad bandwidth coverage.
Data Source
AI summary
The ABB blocks 332, 334, 336, and 318 are configured to process the I/Q signals corresponding to the first or the second HB independently or the I/Q signals corresponding to the LB in cooperation by two. In detail, the first ABB I block 332 and the first ABB Q block 334 operate independently in the 3G/4G mode but they are configured to process the I signal (or Q signal) of the LB in the 2G mode. Likewise, the second ABB Q block 336 and the second ABB I block 318 operate independently in the 3G/4G mode but they are configured to process the Q signal (or I signal) of the LB in the 2G mode. The first ABB I/Q blocks 332 and 334 and the second ABB I/Q blocks 336 and 318 are arranged symmetrically to processing the I/Q signals cooperatively in the 2G mode. In detail, the second ABB Q block 336 is arranged close to the first ABB Q block 334 such that the capacitor regions included in the first ABB I/Q blocks 332 and 334 are connected to each other and the capacitor regions included in the second ABB I/Q blocks 336 and 338 are connected to each other.