RF Front-End Auto-Tuning Using Negative Transconductance Oscillation

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Solution Overview

Problem

Conventional RF front-end circuits with embedded antennas face challenges in accurately and automatically tuning the resonance frequency of the tank to match the desired channel frequency band, particularly in wideband FM reception and transmission applications.

Innovation Solution

A radio-frequency (RF) front-end circuit incorporating a tunable filter, a negative transconductance circuit, and a control circuit that produces a tuning oscillation signal and adjusts the filter to align the frequency within the desired channel range, utilizing a counter and precision clock for accurate frequency determination and adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If conventional filter circuitry is used to tune incoming signals, then signal reception is achieved, but automatic and accurate frequency tuning capability is lacking

Engineering Contradiction:

Improveautomatic tuning capabilityVSAvoidfrequency tuning accuracy

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the oscillation frequency is measured by a counter and fed back to the control circuit. The control circuit automatically adjusts the tuning control signal based on the measured frequency to achieve the desired channel frequency band, enabling automatic and accurate frequency tuning without manual intervention

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces manual mechanical tuning methods with an electronic automatic tuning system. A microcontroller or control circuit automatically generates tuning control signals based on feedback from frequency measurement, substituting the need for manual mechanical adjustment and enabling precise digital control of the tuning process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If embedded antennas are used to provide continuous signal reception, then antenna functionality is maintained, but signal reception strength is reduced by several tens of dB

Engineering Contradiction:

Improvecontinuous reception capabilityVSAvoidsignal reception strength

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the electrical parameters of the embedded antenna system by using a tunable filter with adjustable resonance frequency. By optimizing the filter's Q-factor and resonance frequency to match the desired channel, the system compensates for the inherently weak signal strength of embedded antennas, enabling effective signal reception despite the antenna's small size and limited reception capability

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If tank resonance frequency is tuned for wideband reception, then bandwidth is increased, but automatic frequency measurement and tuning capability is lacking

Engineering Contradiction:

Improvewideband reception capabilityVSAvoidautomatic frequency measurement

Core Design Contradiction:

Adaptability or versatilityVSExtent of automation

Solution Approach 1:

The patent implements a feedback loop where the counter measures the oscillation frequency and provides this information to the control circuit. The control circuit automatically adjusts the tuning control signal based on the measured frequency to ensure the tank resonance is properly tuned to the desired channel within the wideband range, enabling automatic frequency measurement and tuning across the entire bandwidth

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent creates a universal automatic tuning system that can operate across the entire wideband frequency range. The control circuit and counter combination provides a multi-functional solution that automatically handles frequency measurement and tuning for any channel within the wideband reception capability, eliminating the need for separate tuning mechanisms for different frequency ranges

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables quick, accurate, and automatic tuning of the RF front-end circuit to the desired frequency band, enhancing signal reception and transmission capabilities while supporting various embedded antenna configurations.

Implementation Method 1

producing an oscillation signal with a negative transconductance circuit coupled with the tunable filter, the negative transconductance circuit canceling the tank loss

Methodology Applied

Scientific EffectNegative transconductance:

Implementation Method 2

a shunt inductor can be used to resonate with the equivalent capacitance of the embedded antenna 12 to form a high resonance (high-Q) resulting in voltage gain

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS8725098B2Method for tuning a RF front-end circuit using an on-chip negative transconductance circuit to make an oscillator

Publication Date: 2014.05.13 MEDIATEK SINGAPORE PTE LTD

AI summary

A radio-frequency (RF) front-end circuit includes a tunable filter, a negative transconductance circuit coupled with the tunable filter to produce a tuning oscillation signal, and a counter arranged to determine a frequency of the tuning oscillation signal. The RF front-end circuit also includes a control circuit arranged to shift the frequency of the tuning oscillation signal by adjusting the tunable filter until the frequency of the tuning oscillation signal falls within an acceptable frequency range corresponding to a desired channel frequency band.