Frequency-Voltage Detection Circuit for PFM/PWM Mode Switching

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Solution Overview

Problem

Conventional frequency detection apparatuses in portable devices face inefficiencies in switching between pulse frequency modulation (PFM) and pulse width modulation (PWM) modes, leading to increased power consumption and larger die size due to the need to detect voltage loads of components other than core components.

Innovation Solution

A frequency detection apparatus comprising a constant current generator and a frequency-voltage conversion unit that generates a voltage output proportional to the input signal frequency, allowing for efficient mode switching between PFM and PWM without detecting non-core component voltage loads, utilizing a comparator to determine when to switch modes based on a predetermined frequency threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional frequency detection apparatus detects voltage loads of non-core components to enable mode switching, then mode switching capability is achieved, but power consumption increases and die size increases

Engineering Contradiction:

Improvemode switching capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts the frequency detection function from a complex voltage load detection system. By using a frequency-voltage conversion unit that converts the frequency of the input signal directly to a voltage level, the system eliminates the need to detect voltage loads of non-core components (such as I/O components), thereby reducing power consumption while maintaining mode switching capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The frequency-voltage conversion unit serves multiple functions: it detects the frequency of the input signal, converts it to a corresponding voltage level, and provides this voltage to the comparator for mode switching decisions. This multi-functional unit replaces multiple separate detection circuits, reducing overall power consumption and simplifying the system architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If conventional frequency detection apparatus detects voltage loads of non-core components, then mode switching capability is achieved, but die size increases

Engineering Contradiction:

Improvemode switching capabilityVSAvoiddie size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the frequency detection function with the existing voltage detection pathway by feeding the output of the frequency-voltage conversion unit into the same comparator that receives voltage detection signals. This integration allows mode switching capability to be achieved without adding separate detection circuits, thereby minimizing die size increase.

Inventive Principle:

Principle #5Merging (Combining)

3Use of energy by moving object

If frequency-voltage conversion unit converts input signal frequency to voltage output, then power consumption is reduced, but circuit complexity is introduced

Engineering Contradiction:

Improvepower consumptionVSAvoidcircuit complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The frequency-voltage conversion unit changes the parameter of the input signal from frequency domain to voltage domain. By converting the frequency of the input signal to a corresponding voltage level using RC time constants, the system enables direct voltage comparison without complex signal processing, reducing overall power consumption while maintaining manageable circuit complexity.

Inventive Principle:

Principle #35Parameter changes

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

This solution enables efficient switching between PFM and PWM, reducing power consumption and prolonging battery life in portable devices by automatically controlling modulation mode based on input signal frequency, thereby minimizing power consumption and heat dissipation.

Implementation Method 1

a first capacitor (1042) coupled between the voltage output terminal (Nout) and a first reference voltage (V1); a second capacitor (1046) coupled between the second connection terminal of the first transistor and the first reference voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS8970255B2Frequency detection apparatus with internal output voltage which changes along with input signal frequency

Publication Date: 2015.03.03 REALTEK SEMICON CORP

AI summary

A frequency detection apparatus includes: a constant current generator, arranged for providing a constant current to a voltage output terminal; a first capacitor, coupled between the voltage output terminal and a first reference voltage; a first transistor, which has a first connection terminal coupled to the voltage output terminal, a control terminal coupled to an input signal; a second connection terminal, coupled between the second connection terminal of the first transistor and the first reference voltage; a second transistor, which has a first connection terminal coupled to the second connection terminal of the first transistor, a second connection terminal coupled to the first reference voltage, a control terminal coupled to an inverted input signal, which is obtained by inverting the input signal; wherein a voltage output of the voltage output terminal changes with an input signal frequency of the input signal.