Mobile Receiver Diversity Sub-Unit Cross Modulation Noise Suppression
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Solution Overview
Problem
The existing diversity system in mobile terminal receivers experiences cross modulation noise due to coupling between transmitted and received signals, leading to increased system size and cost, particularly due to the use of two RF SAW filters in the sub-receiving unit.
Innovation Solution
Replace one of the RF SAW filters in the sub-receiving unit with a high-pass filter (HPF) to attenuate low-band frequencies, allowing the HPF to be integrated on-chip, thereby reducing system size and cost while maintaining signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If two BPFs are used in the sub-receiving unit to filter transmitted signal leakage, then cross modulation noise is suppressed, but system size and production cost increase
Solution Approach 1:
The invention extracts and removes one of the two BPFs from the sub-receiving unit, replacing it with an HPF. This reduction in component count directly decreases system size while maintaining cross modulation noise suppression through the combined filtering action of the remaining BPF and HPF
Solution Approach 2:
The HPF is designed to perform multiple functions: it filters low-band frequency transmitted signal leakage that passes through the BPF, and works in conjunction with the BPF to provide comprehensive frequency filtering. This multi-functional approach allows one component to do the work of what would traditionally require two separate BPFs
2Reliability
If two RF SAW filters are used in the sub-receiving unit, then signal filtering performance is improved, but production cost increases
Solution Approach 1:
The invention replaces one expensive RF SAW filter (BPF) with a more economical HPF implementation. The HPF can be realized using simple RC circuits or integrated circuit techniques that are significantly cheaper than RF SAW filter technology, thereby reducing production cost while maintaining adequate filtering performance
Solution Approach 2:
The invention changes the filtering approach from using two identical RF SAW filters to using a BPF combined with an HPF. This parameter change in filter type and configuration allows for cost reduction through the use of simpler, more manufacturable HPF circuits while preserving the necessary signal filtering performance through complementary frequency selection
3Device complexity
If an HPF is integrated on-chip instead of using a separate BPF, then system size is reduced, but filtering capability must be maintained
Solution Approach 1:
The invention merges the HPF function with the existing BPF in the sub-receiving unit, creating a combined filtering system. The HPF is positioned to handle low-band frequencies that pass through the BPF, and the two filters work together as an integrated frequency selection system, reducing the need for separate discrete components
Solution Approach 2:
The HPF acts as an intermediary filtering stage between the BPF and the LNA in the sub-receiving unit. It mediates the signal path by providing additional frequency selectivity for low-band signals that the BPF alone cannot sufficiently attenuate, thereby maintaining filtering capability while enabling more compact integration
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 cross modulation noise by additional attenuation of transmitted signal leakage, allowing for a smaller and less expensive mobile terminal receiver with improved sensitivity, as the HPF further filters the signal components, eliminating the need for an additional BPF and reducing production costs.
Implementation Method 1
a band-pass filter for greatly attenuating a low-band frequency of the part of the transmitted signal received through the sub-antenna
Implementation Method 2
a high-pass filter for additionally attenuating the part of the transmitted signal attenuated through the band-pass filter
Data Source
AI summary
Disclosed is an apparatus in a diversity system of a mobile terminal having a main receiving unit and a sub-receiving unit, which includes a sub-antenna for receiving an input signal and a part of a transmitted signal of a transmitting unit, a band-pass filter (BPF) designed to greatly attenuate a low-band frequency of the part of the transmitted signal received through the sub-antenna, a high-pass filter (HPF) for additionally attenuating the part of the transmitted signal attenuated through the BPF, a low-noise amplifier for minimizing a noise of an output value of the HPF, an HPF for passing therethrough only a high-frequency component of an output value of the low-noise amplifier, and a mixer for mixing output values of the HPF and outputting a baseband signal. One of two BPFs in the sub-receiving unit is replaced by one HPF, and thus the HPF can be fabricated on chip with the terminal receiving unit. Additionally, through the on-chip HPF, the use of an additional BPF is eliminated, and the size and the unit price of production of the mobile terminal can also be reduced.