Integrated Transformer Signal Isolator Design
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Solution Overview
Problem
Existing signal isolators face challenges in maintaining digital and analog signal integrity across a magnetically coupled galvanic isolation barrier, particularly in achieving wide bandwidth and minimizing propagation delay for digital signals, and linearity for analog signals, while also requiring efficient power management without separate bias supplies.
Innovation Solution
A multilayer substrate with parallel conductive layers separated by insulation, featuring a transformer with loosely coupled windings and high-frequency oscillator circuits powered exclusively by the input signal, where the detector circuit is powered through the transformer, enabling efficient signal modulation and isolation with reduced magnetically permeable material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isolation transformer with separate bias supplies is used, then galvanic isolation is provided, but device complexity and power management requirements increase
Solution Approach 1:
The patent combines the primary and secondary windings into a single integrated transformer structure fabricated on the same substrate, eliminating the need for separate bias supplies. The primary winding receives the input signal and the secondary winding provides the isolated output, with both windings magnetically coupled through a shared magnetic core formed in the substrate.
Solution Approach 2:
The integrated transformer serves multiple functions: it provides galvanic isolation between input and output, transfers power from primary to secondary side, and enables signal coupling across the isolation barrier. The magnetic core structure simultaneously supports both windings and provides the necessary magnetic coupling path.
2Reliability
If wide bandwidth is achieved for digital signal transfer, then signal integrity is maintained, but propagation delay increases
Solution Approach 1:
The patent optimizes the magnetic coupling coefficient between primary and secondary windings by adjusting the magnetic core geometry and winding configuration. This parameter optimization enables wide bandwidth operation with minimized propagation delay, achieving a balance between signal integrity and timing performance.
3Reliability
If magnetic shielding is enhanced to reduce interference, then signal quality improves, but magnetically permeable material usage increases
Solution Approach 1:
The patent implements magnetic shielding only in specific regions where interference is most problematic, rather than using extensive magnetic material throughout the entire device. The magnetic core is strategically positioned to provide necessary coupling while minimizing unnecessary magnetic material that would increase interference.
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 achieves effective galvanic isolation with high-frequency signal transfer, maintaining signal integrity and reducing interference, while eliminating the need for separate power connections, thus enhancing breakdown voltages and operational efficiency.
Implementation Method 1
A transformer is formed in the region between the upper conductive shield and lower conductive shield. The transformer may include a primary winding formed in a third conductive layer of the substrate and a secondary winding formed in a fourth conductive layer of the substrate. The region may provide space for a magnetic field coupling the windings.
Implementation Method 2
A first high frequency oscillator circuit may have an input for receiving an input signal and be connected to excite the primary winding at a first frequency in response to the input signal.
Implementation Method 3
A first detector circuit may be coupled to the secondary winding and may have a first output. The first detector circuit may be adapted to selectively sense the first frequency and be configured to provide an output signal via the first output in response to the first oscillator exciting the primary winding.
Data Source
AI summary
A signal isolator comprises a multilayer substrate with conductive layers separated by insulation. A region within the substrate is defined by upper and lower conductive shields. A transformer, including primary and secondary windings, is formed in the region. Circuitry supported on an upper conductive layer includes a high frequency oscillator for receiving an input signal, the high frequency oscillator being connected to excite the primary winding in response to the signal. A detector circuit coupled to the secondary winding is adapted to provide an output signal in response to the high frequency oscillator excitation of the primary winding. The circuitry may be powered exclusively by power received from the input signal. The oscillator may modulate the primary excitation and the detector may vary the magnitude of the output in response to the modulation. A plurality of isolator channels may be provided on a single multilayer substrate.