Radio Oscillator Tuning via Successive Approximation

Solution Overview

Problem

Existing digital electronic devices, such as radios, face challenges in synchronizing high frequency clocks with crystal clocks efficiently, leading to long settling times and excessive power consumption due to the use of phase or frequency locked loops, especially when using low frequency crystal oscillators like a 32.768 KHz watch crystal oscillator.

Innovation Solution

A method is introduced to rapidly tune a radio oscillator frequency to a reference frequency using a successive approximation algorithm and an adjustable capacitor array, where the oscillator is set to a maximum value and bits are toggled based on frequency measurements relative to the reference, allowing for rapid convergence and power-saving by disabling the tuning circuit post-synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phase locked loop or frequency locked loop is used to synchronize high frequency clock with crystal clock, then synchronization stability is improved, but settling time increases and power consumption increases

Engineering Contradiction:

Improvesynchronization stabilityVSAvoidsettling time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing the optimal tuning values for the voltage controlled oscillator in a lookup table before operation. When synchronization is needed, the system simply retrieves the pre-computed value instead of performing real-time iterative adjustment, thereby eliminating the long settling time associated with traditional phase/frequency locked loops while maintaining synchronization accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical/continuous adjustment mechanism of phase locked loops with a digital lookup table approach. Instead of using continuous feedback control with analog components, the system uses discrete pre-computed values stored in memory, substituting the traditional feedback control mechanism with a table-driven digital solution that achieves faster settling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If phase locked loop or frequency locked loop is used to synchronize clocks, then synchronization stability is improved, but power consumption increases

Engineering Contradiction:

Improvesynchronization stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing the optimal tuning values for the voltage controlled oscillator in a lookup table before operation. When synchronization is needed, the system simply retrieves the pre-computed value instead of performing real-time iterative adjustment, thereby eliminating the long settling time associated with traditional phase/frequency locked loops while maintaining synchronization accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical/continuous adjustment mechanism of phase locked loops with a digital lookup table approach. Instead of using continuous feedback control with analog components, the system uses discrete pre-computed values stored in memory, substituting the traditional feedback control mechanism with a table-driven digital solution that achieves faster settling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If low frequency crystal oscillator is used, then power consumption is reduced, but settling time increases

Engineering Contradiction:

Improvepower consumptionVSAvoidsettling time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing the optimal tuning values for the voltage controlled oscillator in a lookup table before operation. When synchronization is needed, the system simply retrieves the pre-computed value instead of performing real-time iterative adjustment, thereby eliminating the long settling time associated with traditional phase/frequency locked loops while maintaining synchronization accuracy.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7375594B1Radio oscillator tuning

Publication Date: 2008.05.20 ANALOG DEVICES INT UNLTD CO

AI summary

Tuning a radio oscillator frequency to a reference frequency is disclosed. A radio oscillator is set using a predetermined value loaded into an adjustment bit array. A highest selected bit is selected to be used in locating a final tuned value for the adjustment bit array. The final tuned value is determined by successively setting a selected bit starting with the highest selected bit in the adjustment bit array. And, the selected bit value in the final tuned value is determined using a measurement of the radio oscillator frequency and its relation to a reference frequency.