Bidirectional RF Isolator Using Magnetic Coupling
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Solution Overview
Problem
Existing digital isolators in power conversion products face challenges such as start-up synchronization issues, error detection difficulties due to long pulse periods, lack of common mode rejection in capacitive coupling, and significant RF interference from cellular telephones, which affect the reliability and efficiency of high-speed digital links.
Innovation Solution
An integrated circuit single chip isolator provides bidirectional data transfer with serialized digital data and synchronization clock signals across a voltage isolation barrier, using transformers for magnetic coupling and amplitude modulation to achieve high isolation and reject common mode signals, while minimizing RF interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If magnetic pulse couplers are used for digital isolation, then high-speed data transfer is achieved, but start-up synchronization issues and error detection difficulties occur
Solution Approach 1:
The patent applies preliminary action by implementing a start-up sequence where the detector first detects a predetermined number of logic one states before entering a data reception state. This preliminary detection phase ensures proper synchronization is established before actual data transfer begins, preventing synchronization issues while maintaining high-speed operation
Solution Approach 2:
The patent implements feedback mechanisms through acknowledgment signals sent from detector to driver. The detector sends acknowledgment logic one states back to the driver to confirm successful data reception, enabling error detection and retransmission when errors occur, thereby improving reliability without sacrificing data transfer speed
2Reliability
If capacitive coupling is used for isolation, then isolation is provided, but common mode rejection is lacking
Solution Approach 1:
The patent uses magnetic coupling through transformers as an intermediary mechanism between the driver and detector circuits. This magnetic coupling provides both isolation and inherent common mode rejection, as the transformer only transfers differential signals while blocking common mode voltages, thus eliminating the harmful effects present in capacitive coupling solutions
3Reliability
If high isolation voltage is implemented, then safety is improved, but RF interference from cellular telephones increases
Solution Approach 1:
The patent employs parameter changes by implementing a spread spectrum technique that modulates the data signal across a wide frequency range rather than using a single frequency. This frequency diversity approach allows the system to maintain high isolation voltage while minimizing susceptibility to RF interference from cellular telephones, as the interference affects only a narrow frequency band compared to the spread spectrum signal
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 enables reliable high-speed digital isolation with up to 5,000 volts of isolation, effective common mode rejection, and reduced RF interference, improving the performance and cost-effectiveness of power supply components.
Implementation Method 1
The first transformer has a primary winding and a secondary winding. The second transformer has a primary winding and a second secondary winding. The first and second primary windings are coupled together to form a first series string. The first and second secondary windings are coupled together to form a second series string.
Implementation Method 2
Some manner for minimizing these large common mode signals at GHz frequencies would be highly desirable.
Implementation Method 3
An integrated circuit single chip isolator provides bidirectional data transfer for a plurality of communications channels
Data Source
AI summary
An isolator provides bidirectional data transfer for a plurality of communications channels. First and second dies are located on first and second sides of a voltage isolation barrier and have a first and second plurality of digital data input/output pins associated therewith. First circuitry on the first die and third circuitry on the second die serializes a plurality of parallel digital data inputs from the digital data input/output pins onto one link across the barrier and transmits synchronization clock signals associated with the digital data inputs over a link across the barrier. Second circuitry on the second die and fourth circuitry on the first die de-serializes the digital data inputs from the first link onto the second digital data input/output pins and receives the first synchronization clock signal associated with the digital data inputs on the second link.