Differential Capacitive Level Shifter Across High-Voltage Barriers
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Solution Overview
Problem
Existing high-speed logic signal transfer across high voltage differences in integrated circuits faces challenges due to transient voltage changes, which require large pulsed currents to maintain accurate signal coupling, necessitating a solution that minimizes the use of such currents.
Innovation Solution
A circuit employing differential coupling capacitors with excess substrate capacitance and a binary flip-flop with set and reset inputs, along with an output signal buffer, to transmit logic signals across high voltage barriers using rapid voltage changes through small capacitors, and incorporating mechanisms for automatic correction and reset to maintain synchronism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large pulsed currents are used in the transfer circuitry to overcome transient voltage changes, then signal transfer reliability is improved, but power consumption and circuit stress increase
Solution Approach 1:
The patent introduces a mediator circuit consisting of coupling capacitors and a flip-flop that transfers logic states across the high voltage barrier without requiring large currents. The coupling capacitors transfer voltage changes, and the flip-flop latches these changes, converting them into stable logic states on the high voltage side, thereby eliminating the need for large pulsed currents while maintaining reliable signal transfer
Solution Approach 2:
The patent replaces the mechanical/electrical approach of using large pulsed currents to force signal transfer with a capacitive coupling and latching mechanism. Instead of pushing signals through high voltage barriers using current, the system uses voltage change detection and state latching, substituting a more efficient electrical mechanism that consumes less power
2Reliability
If large pulsed currents are used to maintain accurate signal coupling across voltage barriers, then signal integrity is improved, but device stress and potential damage increase
Solution Approach 1:
The coupling capacitors act as intermediaries that isolate the high voltage barrier from the signal path. They transfer only the voltage change information without requiring large currents to flow through the barrier, thereby maintaining signal integrity while eliminating the harmful stress that would result from forcing large currents across high voltage differences
Solution Approach 2:
The flip-flop circuit provides beforehand cushioning by latching the logic state once it is detected through the coupling capacitors. This latching mechanism protects the circuit from transient voltage spikes and noise that might otherwise cause false signal transitions, thereby maintaining signal integrity without requiring continuous large currents that would stress the circuit
3Device complexity
If simple coupling methods are used to transfer logic signals across high voltage barriers, then device complexity is reduced, but susceptibility to transient voltage interference increases
Solution Approach 1:
The coupling capacitors provide a simple yet effective intermediary mechanism that blocks DC voltage differences while allowing AC signal transitions to pass. This simple capacitive coupling, combined with the flip-flop latching action, creates a robust system that is inherently immune to transient voltage interference on the high voltage side, achieving high reliability without complex shielding or filtering circuits
Solution Approach 2:
The flip-flop circuit provides self-service by automatically latching the logic state once it is detected through the coupling capacitors. This automatic state capture and holding mechanism eliminates the need for additional complex control circuits to protect against transient interference, maintaining simplicity while achieving high reliability through the self-latching property of the flip-flop
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
Enables efficient transfer of fast logic signals across high voltage differences without large pulsed currents, providing enhanced protection against undesired switching and automatic correction of errors caused by transient conditions, ensuring reliable operation.
Implementation Method 1
A first coupling capacitor is coupled to the true buffer output and to the set input of the binary flip-flop. A second coupling capacitor is coupled to the complement buffer output and to the reset input of the binary flip-flop circuit.
Data Source
AI summary
A circuit for transmitting logic signals across a high voltage barrier has a logic signal buffer with true and complement state differential outputs. A binary flip-flop with set and reset inputs is further provided. A first coupling capacitor is coupled to the true buffer output and to the set input of the binary flip-flop. A second coupling capacitor is coupled to the complement buffer output and to the reset input of the binary flip-flop circuit.