Integrated RF Receiver Front End Without External SAW Filters

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Solution Overview

Problem

Conventional receiver systems face challenges in enhancing receiver linearity, reducing power consumption, and decreasing costs, particularly in hostile RF interference environments, due to their architecture which includes external SAW filters and multiple amplification stages.

Innovation Solution

The integration of a differential Low Noise Amplifier (LNA) transconductor with a mixer and a low input impedance baseband amplifier/filter, eliminating the need for external filters and improving linearity by merging the transconductor with the LNA, thereby directly driving the mixer and enhancing noise figure and linearity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional receiver systems use external SAW filters and multiple amplification stages, then filtering and amplification functions are achieved, but device complexity and cost increase

Engineering Contradiction:

Improvereceiver architecture complexityVSAvoidreceiver linearity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent merges the LNA and transconductor into a single integrated circuit block, eliminating the need for separate external SAW filters and multiple discrete amplification stages. This integration reduces device complexity while maintaining or improving receiver linearity through optimized internal signal paths and impedance matching.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated LNA-transconductor circuit performs multiple functions simultaneously: low-noise amplification, impedance transformation, and signal conditioning for the mixer. This multi-functionality replaces several separate components (LNA, external filters, transconductor), reducing overall system complexity while improving linearity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Power

If conventional receiver systems use multiple amplification stages and external filters, then signal processing is achieved, but power consumption increases

Engineering Contradiction:

Improvepower consumptionVSAvoidreceiver linearity

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

By combining the LNA and transconductor into a single integrated stage, the patent reduces the total number of active components requiring power. The shared biasing circuits and integrated architecture reduce overall power consumption while maintaining the linearity performance needed for hostile RF environments.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conventional receiver systems use external SAW filters, then signal filtering is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvemanufacturing costVSAvoidreceiver linearity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent integrates filtering functions into the LNA-transconductor circuit itself, eliminating the need for separate external SAW filters. This integration reduces the bill of materials and assembly costs while maintaining the necessary signal conditioning and linearity performance through carefully designed internal circuit topology.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7529529B2Low noise, high-linearity RF front end receiver

Publication Date: 2009.05.05 APPLE INC

AI summary

An architecture for a receiver of a wireless device having a Low Noise Amplifier (LNA) transconductor to receive a signal from an antenna, a mixer meshed with the LNA transconductor, and an amplifier/filter meshed with the mixer to provide a baseband output signal.