CDAC Power Amplifier Off-Cap Q Tuning for Back-Off Efficiency

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Solution Overview

Problem

Modern wireless systems face challenges in efficiently supporting multi-band and multi-mode operations due to large chip/module area, increased cost, and loss of power efficiency in power amplifiers (PAs) when using direct assembly or tunable passive networks.

Innovation Solution

Implementing a power amplifier with capacitive digital analog converter (CDAC) cells and an optimization component that dynamically alters the Q Factor of output capacitors in off-mode CDAC cells, optimizing driver sizes for high efficiency modes, reducing impedance, and using separate enhancement components for differential paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If direct assembly of several single-band PAs is used to achieve multi-band operations, then multi-band support is achieved, but chip area increases and power efficiency decreases

Engineering Contradiction:

Improvemulti-band supportVSAvoidpower efficiency

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent merges multiple single-band PA functionalities into a single multi-band PA by integrating a CDAC with multiple capacitive elements that can be dynamically configured. Instead of assembling separate PAs, the invention combines them into one unified structure that supports multiple bands through digital control of the capacitive network, thereby reducing chip area while maintaining multi-band capability and improving power efficiency through optimized signal paths.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs dynamic reconfiguration of the capacitive elements in the CDAC to adapt to different operating bands. By dynamically switching between different capacitor configurations using digital control signals, the PA can optimize its performance for each band, improving power efficiency while maintaining versatility across multiple frequency ranges.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If tunable passive networks are used to achieve multi-band impedance matching, then frequency range increases, but passive loss increases and reliability decreases

Engineering Contradiction:

Improvefrequency rangeVSAvoidpassive loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent replaces traditional mechanical or continuous-tunable passive networks with a digital-controlled capacitive system. Instead of using continuous variable components like varactors that introduce passive loss and reliability issues, the invention uses discrete capacitive elements switched by digital control signals, eliminating the need for lossy tunable components while maintaining wide frequency range adaptability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the electrical parameters of the impedance matching network by digitally switching between different capacitor configurations. This allows the system to adapt to different frequency ranges by changing the effective capacitance values, achieving wideband operation without the passive losses associated with continuous-tunable components.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If tunable components such as varactors and switch-cap banks are used for multi-band operations, then frequency adaptability increases, but reliability decreases due to power efficiency concerns

Engineering Contradiction:

Improvefrequency adaptabilityVSAvoidreliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs simple, robust capacitive elements and digital switches instead of complex, failure-prone tunable components like varactors. The design uses basic semiconductor switches and fixed capacitors that are highly reliable and easy to manufacture, sacrificing the continuous tuning capability but gaining significant improvements in reliability and power efficiency while maintaining sufficient frequency adaptability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS20260100717A1Efficiency enhanced circuit digital-to-analog converter (CDAC) by optimized q of the off-load cap

Publication Date: 2026.04.09 INTEL CORP

AI summary

A communication device includes a power amplifier that generates power signals according to one or more operating bands of communication data, with the amplitude being driven and generated in output stages of the power amplifier. A number of capacitive digital analog converter (CDAC) cells of a power amplifier can be sized to provide defined power signals along a signal path. In response to an optimization component that is coupled to a CDAC cell of the plurality of CDAC cells operating in a high efficiency enable mode and the CDAC cell being powered off in an off mode, the optimization component can increase a power efficiency of the power amplifier by reducing an impedance of an output capacitor of the CDAC cell.