Ground Shift Compensation Circuit for Reliable Bus Data Sampling
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Solution Overview
Problem
In communication systems, ground shift caused by high currents across bus connections, such as USB connections, leads to voltage differences between devices, preventing accurate data sampling and reducing the likelihood of successful data exchange, especially as communication protocols like USB 2.0 are exceeded by increasing current demands.
Innovation Solution
The implementation of ground shift compensation circuitry, which includes amplifier and voltage compensation circuitry, senses ground currents through a sense resistor and generates compensated supply and ground voltages, allowing data communication circuitry to approximate local supply and ground voltages, thereby compensating for ground shift and supporting higher currents without compromising data exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher currents are supplied across bus connections to meet increasing power demands, then power delivery capability is improved, but ground shift increases causing voltage differences between devices
Solution Approach 1:
The patent implements a feedback mechanism where the local device measures its own ground voltage relative to the bus supply voltage, determines the ground shift amount, and uses this information to adjust its sampling voltages. This closed-loop feedback enables the device to compensate for ground shift effects and maintain reliable data exchange even when high currents cause significant ground potential differences.
Solution Approach 2:
The patent dynamically changes the sampling voltages used by the data communication circuitry based on the measured ground shift. By adjusting the sampling voltage parameter according to the actual ground potential difference, the device maintains accurate data sampling despite variations in ground voltage caused by high current operation.
2Reliability
If ground shift compensation circuitry is added to reduce data errors, then data exchange reliability is improved, but device complexity increases
Solution Approach 1:
The voltage measurement and compensation circuitry is designed to serve multiple functions: it measures the ground voltage, determines the ground shift amount, and generates compensated sampling voltages. By making the circuit multi-functional, the patent reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity while achieving reliable ground shift compensation.
3Power
If USB 2.0 communication protocol is exceeded to supply increasing currents, then power delivery is improved, but ground shift prevents accurate data sampling
Solution Approach 1:
The patent performs preliminary measurement of the ground voltage and determination of the ground shift amount before conducting data sampling. By proactively measuring and compensating for the ground shift before the actual data exchange occurs, the system ensures that subsequent sampling operations are performed with accurate reference voltages, maintaining measurement precision even at current levels exceeding USB 2.0 specifications.
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 ground shift compensation circuitry effectively reduces data errors due to ground shift, enabling successful data exchange by approximating local voltages and allowing bus connections to handle higher currents, thus enhancing communication system performance.
Implementation Method 1
an amplifier configured to generate a sense voltage responsive to ground currents at a ground terminal
Implementation Method 2
amplifier circuitry and voltage compensation circuitry, senses ground currents through a sense resistor and generates compensated supply and ground voltages
Data Source
AI summary
An example apparatus includes: a bus connection including a common terminal; a first data terminal; and a second data terminal; an amplifier having an input terminal and an output terminal, the input terminal of the amplifier coupled to the common terminal; charge pump circuitry having an input terminal, a first output terminal, and a second output terminal, the input terminal of the charge pump circuitry coupled to the output terminal of the amplifier; receiver circuitry having an input terminal, a first supply terminal, and a second supply terminal, the input terminal of the receiver circuitry coupled to the first data terminal; and transmitter circuitry having an output terminal, a first supply terminal, and a second supply terminal, the output terminal of the transmitter circuitry coupled to the second data terminal, the first supply terminal of the transmitter circuitry coupled to the first output terminal of the charge pump circuitry.