Integrated Filter-VCO Tuning for Area Reduction

Solution Overview

Problem

Existing filter tuning mechanisms require additional components like PLLs and VCOs, occupying large areas and increasing costs, and are inefficient in addressing process and temperature variations in continuous-time filters.

Innovation Solution

A method and apparatus where a portion of the filter is configured as a VCO circuit for tuning, using a frequency detector and controlling circuit to adjust the driving signal, and a gm replica circuit to maintain temperature stability, eliminating the need for external VCOs and reducing area and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external VCO and PLL components are added for filter tuning, then tuning accuracy is improved, but circuit area and cost increase

Engineering Contradiction:

Improvetuning accuracyVSAvoidcircuit area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent merges the VCO function with the filter structure by configuring a portion of the filter as the VCO circuit. This integration eliminates the need for separate external VCO and PLL components, achieving accurate tuning while reducing circuit area and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The filter structure is designed to serve dual purposes: it functions as both the filter and the VCO circuit for tuning. This multi-functionality allows the same circuit components to perform multiple roles, reducing the overall component count and area while maintaining tuning accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If external VCO and PLL components are added for filter tuning, then tuning accuracy is improved, but device cost increases

Engineering Contradiction:

Improvetuning accuracyVSAvoiddevice cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent merges the VCO function with the filter structure by configuring a portion of the filter as the VCO circuit. This integration eliminates the need for separate external VCO and PLL components, achieving accurate tuning while reducing circuit area and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The filter structure is designed to serve dual purposes: it functions as both the filter and the VCO circuit for tuning. This multi-functionality allows the same circuit components to perform multiple roles, reducing the overall component count and area while maintaining tuning accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If filter portion is configured as VCO circuit for tuning, then area and cost are reduced, but temperature stability becomes challenging

Engineering Contradiction:

Improvecircuit areaVSAvoidtemperature stability

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent employs a gm replica circuit that provides temperature compensation through feedback mechanisms. The replica circuit monitors temperature variations and adjusts the filter parameters accordingly, maintaining temperature stability despite the integrated VCO-filter structure.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses a gm replica circuit that copies the temperature characteristics of the main filter circuit. By creating a replica with identical temperature dependencies, the system can measure and compensate for temperature effects, maintaining stability in the integrated structure.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS7626449B2Apparatus and method for tuning center frequency of a filter

Publication Date: 2009.12.01 MEDIATEK INC

AI summary

A method for tuning a filter is provided. The method includes: enabling a VCO circuit, wherein at least a portion of the VCO circuit is selected from the filter; generating an oscillation signal by the VCO circuit according to a driving signal; comparing the oscillation signal with a reference signal and generating a comparison result; and adjusting the driving signal according to the comparison result.