Differential Charge Pump H-Bridge Voltage Matching

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Solution Overview

Problem

The use of h-bridge circuits in differential charge pumps for PLL circuits can lead to voltage disparities between nodes, increasing charge sharing and jitter, which affects the precision and efficiency of clock signal generation.

Innovation Solution

Incorporating a differential charge pump circuit with a sensing operational amplifier and an h-bridge circuit, where the controlling operational amplifier ensures that the voltage at one node is substantially equal to the voltage at another node, reducing charge sharing and jitter by using sense amplifiers to bias the nodes to match the voltages at the OUT and OUTN nodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an h-bridge circuit is used in differential charge pumps, then the charge pump can operate with differential signals, but voltage disparities between nodes are created leading to increased charge sharing and jitter

Engineering Contradiction:

Improvedifferential signal operationVSAvoidclock signal precision

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies equipotentiality by using sense amplifiers to actively maintain equal voltages at corresponding nodes (OUT and OUTN) during switching operations. The sense amplifiers detect voltage differences and drive the nodes to match potentials, eliminating the voltage disparities that cause charge sharing and jitter while preserving differential signal operation capability

Inventive Principle:

Principle #12Equipotentiality

2Reliability

If voltage control is implemented to match node voltages, then charge sharing and jitter are reduced, but circuit complexity increases due to additional sensing and controlling operational amplifiers

Engineering Contradiction:

Improveclock signal precisionVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of voltage sensing, comparison, and correction into integrated operational amplifier circuits that work together as a unified control system. The sense amplifiers and controlling amplifiers are combined to form a coordinated voltage matching mechanism that achieves precise node voltage control without requiring entirely separate control circuits for each function

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If sense amplifiers are used to bias nodes to match voltages, then noise and jitter are reduced, but power consumption increases

Engineering Contradiction:

ImprovePLL operation stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The sense amplifiers and voltage matching circuitry operate periodically during switching transitions rather than continuously. The control mechanism activates to correct voltage disparities at critical moments during the charging and discharging cycles, then remains inactive during stable periods, reducing overall power consumption while maintaining PLL operation stability

Inventive Principle:

Principle #19Periodic action

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 configuration reduces noise and jitter in the PLL circuit, improving the operation of the differential charge pump and PLL by minimizing voltage differences and excess current flow, thus enhancing the stability and accuracy of clock signal control.

Implementation Method 1

The h-bridge circuit is configured to control a voltage at a first node so that the voltage at the first node is substantially equal to a voltage at a second node for a plurality of voltages at the second node

Methodology Applied

Scientific EffectOperational amplifier voltage sensing and comparison:

Implementation Method 2

The h-bridge circuit includes a first transistor coupled to the first node and the second node. The voltage at the first node is controlled using the first sensing operational amplifier and the first transistor

Methodology Applied

Scientific EffectElectrical voltage control through switching:

Implementation Method 3

The differential charge pump circuit includes a first independent current source, a second independent current source, and an h-bridge circuit coupled to the first and second independent current sources. The first independent current source drives a first portion of the h-bridge circuit and the second independent current source drives a second portion of the h-bridge circuit

Methodology Applied

Scientific EffectIndependent current source operation:

Data Source

PatentUS10644709B2Efficient differential charge pump with sense and common mode control

Publication Date: 2020.05.05 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A differential charge pump circuit for use in a phase-locked loop (PLL) circuit is disclosed. The circuit includes a reference current, two sense amplifiers, a common mode control amplifier, and an h-bridge circuit. The h-bridge circuit is coupled to the reference current and the common mode control amplifier. The reference current drives a first portion of the h-bridge circuit and the common mode control amplifier controls a second portion of the h-bridge circuit. The h-bridge circuit also includes first and second nodes. The circuit controls a voltage at the first node so that it is substantially equal to a voltage at the second node for a plurality of voltages at the second node.