Diversity Receiver SAW Filter Cost Reduction

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Solution Overview

Problem

Conventional wireless receiver systems with antenna diversity face increased costs due to the use of SAW filters to mitigate interference from strong cellular CDMA transmissions, which also degrade the noise figure and require costly filtering in each receiving channel.

Innovation Solution

A diversity receiver system with two receiving channels, where only the first channel includes a SAW filter and amplifier, and the second channel uses a received signal strength indicator (RSSI) to detect blocker signals, allowing the diversity baseband processor to assign weights and potentially bypass the second channel when a blocker signal is detected, thereby eliminating the need for a second SAW filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a SAW filter is used in each receiving channel to attenuate blocker signals, then the receiver can effectively mitigate interference from strong cellular transmissions, but the cost increases and the noise figure degrades

Engineering Contradiction:

Improveinterference from blocker signalsVSAvoidcost and noise figure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention divides the diversity receiver into two distinct paths: a first receiving channel with a SAW filter for strong blocker attenuation, and a second receiving channel without a SAW filter for weaker blocker conditions. This segmentation allows the system to use filtering only when necessary, reducing overall cost and noise figure while maintaining effective interference mitigation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between using the first receiving channel (with SAW filter) and the second receiving channel (without SAW filter) based on the strength of the blocker signal. The diversity controller adjusts the weighting or selection of channels in real-time, making the filtering application adaptive rather than static, thereby optimizing the trade-off between interference rejection and noise figure.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If SAW filters are installed in all receiving channels, then blocker signal attenuation is maximized, but the overall system cost increases significantly

Engineering Contradiction:

Improveblocker signal interferenceVSAvoidsystem cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The receiver is segmented into multiple channels with different filtering configurations. Only the first receiving channel includes a SAW filter, while the second receiving channel omits it. This selective segmentation reduces the total number of expensive SAW filters required while maintaining adequate blocker attenuation through diversity combining.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention replaces expensive SAW filters with a cheaper diversity switching mechanism. Instead of deploying costly filters in every channel, the system uses a single SAW filter in one channel and relies on electronic diversity control to achieve similar overall performance, effectively substituting expensive hardware with a more economical architecture.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 configuration enhances reception characteristics while reducing costs by avoiding the noise figure degradation and cost associated with multiple SAW filters, maintaining effective operation even when transceivers are not transmitting, and improving diversity mode performance.

Implementation Method 1

The first receiving channel includes, in part, a saw filter

Methodology Applied

Scientific EffectSurface Acoustic Wave filtering: Surface Acoustic Wave

Implementation Method 2

a received signal strength indicator (RSSI) operative to detect blocker signals

Methodology Applied

Scientific EffectSignal strength detection:

Implementation Method 3

the diversity baseband processor to combine the signals it receives from first and second receiving channels

Methodology Applied

Scientific EffectSignal combining and weighting:

Data Source

PatentUS9231685B2Diversity blocker protection

Publication Date: 2016.01.05 MAXLINEAR INC

AI summary

A transmitting/receiving circuit includes, in part, at least one transceiver, and at least two receiving channels forming a diversity receiver. One of the receiving channels includes, in part, a saw filter, an amplifier, and a frequency converter. The other receiving channel includes, in part, an amplifier, a frequency converter, and a received signal strength indicator (RSSI) adapted to detect signals transmitted by the transceiver. The RSSI is optionally coupled to an input terminal of its associated amplifier. The receiver further includes, in part, at least one processor operative to combine signals processed through the first and second receiving channels using a weight the processor assigns to the signal received by the second receiving channel in accordance with a strength of the blocker signal that the RSSI detects. The second receiving channel optionally includes an RSSI.