Programmable Resistor for On-Package Decoupling Capacitor Voltage Droop

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Solution Overview

Problem

Conventional power distribution networks (PDNs) face challenges in reducing voltage droop due to high impedance, particularly at resonance frequencies, which can lead to timing failures and reliability issues in integrated circuits, as extremely low ESL on-package decoupling capacitors (OPDs) result in low ESR, causing significant voltage droop and potential catastrophic failures.

Innovation Solution

Incorporating a programmable resistor formed from thin-film transistors (TFTs) in series with the on-package decoupling capacitor (OPD) between the supply voltage and ground conductor, allowing for adjustable ESR to optimize impedance characteristics and reduce voltage droop without increasing voltage droop or reducing power supply efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If OPDs with extremely low ESL are used, then inductance is reduced, but ESR becomes extremely low causing degraded impedance peaks at resonance frequencies

Engineering Contradiction:

ImproveESL (Effective Series Inductance)VSAvoidimpedance peaks at resonance frequencies

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The patent introduces a programmable resistor that allows dynamic adjustment of the ESR parameter in the OPD circuit. By changing the resistance value through programming, the system can optimize the ESR to be non-zero at resonance frequencies, thereby maintaining impedance peaks while keeping ESL extremely low. This parameter adjustment resolves the contradiction between low inductance and reliable impedance characteristics.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If ESR is reduced to achieve lower voltage droop, then voltage droop decreases, but impedance peaks at resonance frequencies are degraded

Engineering Contradiction:

Improvevoltage droopVSAvoidimpedance peaks at resonance frequencies

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent employs a programmable resistor that enables dynamic adjustment of ESR based on operating conditions. The resistor can be programmed to provide appropriate resistance values at different frequencies, particularly maintaining non-zero ESR at resonance frequencies to preserve impedance peaks, while allowing lower ESR at other frequencies to reduce voltage droop. This dynamic adaptability resolves the static contradiction between voltage droop reduction and impedance peak maintenance.

Inventive Principle:

Principle #15Dynamics

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

The programmable resistor effectively tunes the impedance of the PDN to reduce voltage droop and noise at resonant frequencies, enhancing the performance and reliability of integrated circuits by allowing for precise adjustment of resistance values to match target impedance specifications.

Implementation Method 1

a programmable resistor formed from at least one thin-film transistor (TFT)

Methodology Applied

Scientific EffectField effect:

Data Source

PatentUS11430797B2Package embedded programmable resistor for voltage droop mitigation

Publication Date: 2022.08.30 QUALCOMM INC

AI summary

Disclosed are devices and methods having a programmable resistor and an on-package decoupling capacitor (OPD). In one aspect a package includes an OPD and a programmable resistor formed from at least one thin-film transistor (TFT). The programmable resistor is disposed in series with the OPD between a supply voltage (VDD) conductor and a ground conductor.