Capacitive Isolation Circuit With Dual Carriers for Symmetric Data Timing
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Solution Overview
Problem
Existing galvanically-isolated communication circuits face challenges with robustness against common mode transients, asymmetric propagation delays, asymmetric current consumption, and jitter, particularly in pulse transmission and OOK modulation techniques.
Innovation Solution
A communication circuit design using two parallel channels with high-voltage capacitors for transmitting carrier signals during asserted and de-asserted logic levels, combined with a receiver that demodulates these signals and a selector to produce the output signal, ensuring symmetric propagation delays and constant current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulse transmission technique is used for galvanically-isolated communication, then data transmission is achieved, but robustness against common mode transients deteriorates
Solution Approach 1:
The patent employs periodic carrier wave transmission instead of transient-based pulse transmission. The continuous periodic carrier allows for consistent signal detection and enables the receiver to distinguish between carrier presence/absence and common mode transient interference, thereby maintaining robustness during transient events.
Solution Approach 2:
The system pre-establishes a continuous carrier wave before data transmission begins. This preliminary continuous signal provides a stable reference that allows the receiver to detect data modulations reliably even when common mode transients occur, preventing signal loss during transient periods.
2Productivity
If OOK modulation is used for galvanically-isolated communication, then data transmission is achieved, but asymmetric propagation delays occur
Solution Approach 1:
The patent intentionally uses asymmetric modulation schemes where the presence and absence of carrier signals have different transmission characteristics. By designing the system to accommodate and compensate for this inherent asymmetry through synchronized timing and reference signals, the patent achieves reliable data transmission while managing propagation delay variations.
Solution Approach 2:
The system incorporates timing synchronization and reference signal mechanisms that provide feedback to the receiver about the actual transmission timing. This allows the receiver to compensate for asymmetric propagation delays by adjusting its sampling and detection timing based on the observed carrier wave characteristics.
3Productivity
If OOK modulation is used for galvanically-isolated communication, then data transmission is achieved, but asymmetric current consumption occurs
Solution Approach 1:
The continuous periodic carrier transmission ensures that the transmitter operates at a consistent power level regardless of the data being transmitted. This eliminates the asymmetric current consumption inherent in OOK modulation where the transmitter must be fully on or fully off, by maintaining a steady operating state that consumes constant energy.
4Productivity
If pulse transmission technique is used for galvanically-isolated communication, then data transmission is achieved, but jitter occurs
Solution Approach 1:
The patent uses continuous periodic carrier waves as the basis for data transmission, which provides a stable and predictable timing reference. This eliminates the timing jitter inherent in pulse transmission techniques where variable pulse widths and intervals are used, as the periodic carrier maintains consistent frequency and phase relationships throughout transmission.
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 solution provides improved robustness to common mode transients, symmetric propagation delays, constant current consumption, and eliminates jitter, while maintaining signal integrity.
Implementation Method 1
A first capacitive isolation barrier has a first terminal coupled to the output of the first transmitter to propagate the first carrier signal. A second capacitive isolation barrier has a first terminal coupled to the output of the second transmitter to propagate the second carrier signal.
Data Source
AI summary
A galvanically-isolated communication circuit includes a first transmitter transmitting a first carrier while the input data signal is asserted, and a second transmitter transmitting a second carrier while the input data signal is de-asserted. A first capacitive barrier, coupled to the first transmitter, propagates the first carrier, and a second capacitive barrier, coupled to the second transmitter, propagates the second carrier. A receiver demodulates the first carrier from the first capacitive barrier to produce a replica of the input data signal and demodulates the second carrier from the second capacitive barrier to produce a complemented replica of the input data signal. An output data signal is produced by: passing the replica after a masking time interval elapses following a falling edge of the output data signal, and passing a complement of the complemented replica after the masking time interval elapses following a rising edge of the output data signal.