Linearized Transmitter Circuit Phase Training

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Solution Overview

Problem

Current wireless communication systems face challenges in achieving rapid transmitter linearization and minimizing adjacent channel interference due to I-Q quadrature imbalances and the need for multiple polyphase quadrature generators, which can introduce noise and phase ambiguity.

Innovation Solution

A wireless communication unit with a linearized transmitter architecture that employs a new quadrature generation and phase shifting method, utilizing a divide-by-2 quadrature generator and open-loop phase training on the downmixer, followed by closed-loop phase adjustments on the upmixer to compensate for I-Q imbalances, reducing the need for costly circulators and minimizing adjacent channel interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple polyphase quadrature generators are used to cover wideband frequencies, then frequency coverage is improved, but noise and phase ambiguity increase

Engineering Contradiction:

Improvefrequency coverageVSAvoidnoise and phase ambiguity

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A single polyphase quadrature generator is designed to handle wideband frequencies through dynamic reconfiguration. The system uses a single generator that can be dynamically adjusted to cover different frequency ranges, eliminating the need for multiple dedicated generators while maintaining wideband coverage capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements dynamic phase training and reconfiguration mechanisms that allow the single quadrature generator to adapt to different frequency bands in real-time. This dynamic adjustment enables the system to maintain optimal performance across wideband frequencies without the noise and phase ambiguity issues associated with multiple static generators.

Inventive Principle:

Principle #15Dynamics

2Reliability

If closed-loop phase training is used for the upmixer, then transmitter linearity is improved, but training time and complexity increase

Engineering Contradiction:

Improvetransmitter linearityVSAvoidtraining time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The phase training process is segmented into distinct stages: open-loop initial training for the downmixer, followed by closed-loop training for the upmixer. This segmentation allows each stage to be optimized independently, reducing overall training time while maintaining linearity requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Open-loop phase training is performed as a preliminary step before closed-loop training. This preliminary action establishes initial phase relationships and reduces the complexity of subsequent closed-loop training, thereby reducing total training time while still achieving the required transmitter linearity.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If I-Q quadrature imbalances are not corrected, then device complexity is reduced, but adjacent channel interference increases

Engineering Contradiction:

Improvedevice complexityVSAvoidadjacent channel interference

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent implements feedback mechanisms that measure and correct I-Q quadrature imbalances in real-time. The system continuously monitors phase relationships and applies corrective adjustments, eliminating adjacent channel interference without requiring overly complex hardware configurations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts phase and amplitude parameters to correct I-Q imbalances. By changing these parameters through software-controlled adjustments rather than hardware reconfiguration, the system maintains low device complexity while effectively reducing adjacent channel interference.

Inventive Principle:

Principle #35Parameter changes

4Object-generated harmful factors

If Cartesian feedback linearisation is used, then out-of-band emissions are reduced, but DC to RF power conversion efficiency decreases

Engineering Contradiction:

Improveout-of-band emissionsVSAvoidDC to RF power conversion efficiency

Core Design Contradiction:

Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The system applies linearisation techniques selectively and partially, focusing correction efforts on the most critical frequency bands and modulation characteristics. This partial application of Cartesian feedback reduces out-of-band emissions to acceptable levels while minimizing the impact on power conversion efficiency by avoiding excessive correction in all bands.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS8175553B2Wireless communication unit, linearised transmitter circuit and method of linearising therein

Publication Date: 2012.05.08 MOTOROLA SOLUTIONS INC

AI summary

A wireless communication unit includes a linearised transmitter having a forward path and a feedback path, respectively comprising at least one up-mixer and down-mixer, and forming two loops in quadrature. A phase training signal is applied to the at least one down-mixer in the feedback path in an open loop mode of operation to identify a loop phase adjustment to be applied. At least one of the two loops is switched to a closed loop mode of operation and the loop phase adjustment is applied to at least one up-mixer located in the forward path.