Multi-Stage ALC Circuit for Wide-Range Output Power Stability

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Solution Overview

Problem

Existing ALC circuits have limited attenuation linear range, leading to power fluctuations when handling high power signals, affecting stability and test performance.

Innovation Solution

Implementing at least two stages of ALC loops with amplifiers, couplers, power detectors, and attenuation control modules to stabilize output power across a wider dynamic range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single stage of ALC loop is used, then the device complexity is low, but the attenuation linear range is limited causing power fluctuations in high power scenarios

Engineering Contradiction:

Improvepower stabilityVSAvoidALC loop stages

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the ALC system into multiple stages (first stage ALC loop and second stage ALC loop), where each stage handles a specific power range. This segmentation allows the system to maintain power stability across a wider dynamic range by assigning different attenuation control tasks to different stages, resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If multiple stages of ALC loops are implemented, then the output power stability across large dynamic range is improved, but the device complexity increases

Engineering Contradiction:

Improvedynamic rangeVSAvoidALC loop stages

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic switching between different ALC loops based on the current power level. The switching module dynamically selects which ALC loop to activate (first or second stage) depending on the operating conditions, allowing the system to adapt to different power ranges while managing complexity through intelligent control rather than permanently activating all stages.

Inventive Principle:

Principle #15Dynamics

3Reliability

If an adjustable attenuator with large attenuation range is used, then the power fluctuation in high power scenarios is reduced, but the attenuation linear range is still limited

Engineering Contradiction:

Improvepower fluctuation controlVSAvoidattenuation linear range

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent segments the attenuation control function across multiple ALC loops, where each loop is optimized for a specific power range. This allows each attenuator to operate within its linear range while the overall system achieves wide dynamic range coverage through coordinated operation of multiple stages, resolving the contradiction between power fluctuation control and attenuation linear range.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12445101B2Automatic level control circuit, signal source, method for controlling signal source output power, and storage medium

Publication Date: 2025.10.14 ZTE CORP

AI summary

Provided are automatic level control (ALC) circuit, signal source, method for controlling signal source output power, and storage medium. The ALC circuit includes: at least two stages of ALC loops, each ALC loop including an amplifier, a coupler, a power detector, and an attenuation control module connected sequentially. An output end of an adjustable attenuator is connected to an input node of first stage of ALC loop; an output node of each stage of ALC loop, other than last stage of ALC loop, is connected to a normally on end of a two-way single-on switch, a first gating end of the two-way single-on switch is connected to an input node of a next stage of ALC loop, and the output node of the last stage of ALC loop and a second gating end of each two-way single-on switch are connected to an output end of the ALC circuit.