Capacitive Differential Level Shifter for Fast High-Voltage Logic
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Solution Overview
Problem
Existing high speed DC coupled logic level translators require large pulsed currents to transfer logic signals across high voltage differences, which is power inefficient and sensitive to voltage transients, necessitating a solution that minimizes current usage and maintains signal integrity.
Innovation Solution
A high speed logic signal level shifter employing a logic signal buffer with differential outputs and binary flip-flop circuit, utilizing coupling capacitors to transmit rapid voltage changes, thereby reducing the need for large pulsed currents and enhancing protection against voltage supply changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large pulsed currents are used in the transfer circuitry to transfer logic signals across high voltage differences, then signal transfer reliability is improved, but power consumption increases and the circuit becomes more complex
Solution Approach 1:
The patent introduces coupling capacitors as intermediary elements between the high voltage and low voltage circuit sections. These capacitors couple the logic signals across the voltage barrier without requiring large current pulses, thereby reducing power consumption while maintaining signal transfer reliability. The capacitors act as mediators that transfer signal information through voltage changes rather than current pulses.
Solution Approach 2:
The patent changes the operating parameter from large current pulses to small voltage changes for signal transfer. By detecting voltage changes across the coupling capacitors rather than relying on large current pulses, the circuit achieves reliable signal transfer with minimal power consumption. This parameter change from current-based to voltage-based signaling resolves the contradiction between reliability and power consumption.
2Reliability
If large pulsed currents are used to transfer logic signals, then signal integrity is maintained, but the circuit complexity increases
Solution Approach 1:
The coupling capacitors serve as simple intermediary elements that replace complex current pulse generation circuitry. By using passive capacitive coupling instead of active current pulse generators, the patent maintains signal integrity while significantly reducing circuit complexity. The capacitors naturally filter and couple the signals without requiring additional control logic or complex drive circuits.
3Speed
If the circuit is made sensitive to voltage transients for fast signal detection, then signal transfer speed is improved, but the circuit becomes more vulnerable to noise and interference
Solution Approach 1:
The patent extracts only the essential signal information (voltage changes) from the transmitted signal while ignoring transient noise and interference. The coupling capacitors naturally pass only the changing signal components while blocking DC and slow-varying noise. This extraction of useful signal information from the transient-ridden environment allows fast signal transfer while reducing vulnerability to noise.
Solution Approach 2:
The patent converts the harmful effect of voltage transients into a beneficial feature. By using coupling capacitors, the circuit transforms transient noise into transient current pulses that can be easily detected and distinguished from steady-state conditions. The transients that would normally be harmful are converted into the very signal mechanism used for fast, reliable detection.
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 effectively transfers fast logic signals across high voltage differences with minimal propagation delay and reduced sensitivity to voltage transients, using small capacitors that operate 10 times faster than expected voltage transients, thus improving power efficiency and signal stability.
Implementation Method 1
a first coupling capacitor connected from the true buffer output to the set input of the binary flip-flop circuit; and a second coupling capacitor connected from the complement buffer output to the reset input of the binary flip-flop circuit. The high speed logic level shifter transfers a fast logic signal across a high voltage difference by making use of rapid voltage changes transmitted through small capacitors.
Data Source
AI summary
A high speed logic signal level shifter is comprised of: a logic signal buffer for receiving logic signal information and having true and complement state differential outputs; a binary flip-flop circuit with set and reset inputs; a first coupling capacitor connected from the true buffer output to the set input of the binary flip-flop circuit; and a second coupling capacitor connected from the complement buffer output to the reset input of the binary flip-flop circuit. The high speed logic signal level shifter transfers a fast logic signal across a high voltage difference by making use of rapid voltage changes transmitted through small capacitors. The signal changes carried by the capacitors are about 10 times faster than any expected voltage transient on VPP or VNN. Furthermore, the differential coupling circuit is used to provide enhanced protection against undesired circuit switching during supply voltage changes.