Capacitive Level Shifter Across Ground Domains on a Single Die
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Solution Overview
Problem
Existing level shifter circuits fail to effectively translate signals across different ground domains, leading to inefficiencies and increased complexity and cost due to the need for multiple dies to accommodate DC or AC voltage differences.
Innovation Solution
A single-die level shifter circuit design that includes a driver circuit, receiver circuit, capacitors, and substrate bias circuit, capable of translating signals across ground domains while tolerating DC or AC voltage differences, using capacitive coupling and substrate biasing to reduce noise and protect the integrated circuit from excessive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional level shifter circuits are used to translate signals across different ground domains, then signal translation is achieved, but the circuit complexity and cost increase due to requiring multiple dies to accommodate DC or AC voltage differences
Solution Approach 1:
The patent combines multiple level shifting functions into a single integrated circuit die. The first and second level shifters are integrated on the same semiconductor die, along with the substrate bias circuit. This merging eliminates the need for multiple separate dies, reducing overall circuit complexity while maintaining the ability to translate signals across different ground domains with both DC and AC coupling capabilities.
Solution Approach 2:
The integrated circuit performs multiple level shifting functions simultaneously. The first level shifter handles DC-coupled signals while the second level shifter handles AC-coupled signals, and both are managed within the same device. The substrate bias circuit provides additional functionality by adjusting substrate voltage to prevent latchup. This multi-functionality allows a single device to replace what would traditionally require multiple separate components.
2Reliability
If multiple dies are used to accommodate different voltage domains, then voltage differences are managed, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent integrates multiple voltage domain handling circuits on a single semiconductor die. The first and second level shifters, along with the substrate bias circuit, are all fabricated together on the same die using standard CMOS or BiCMOS processes. This single-die implementation maintains proper voltage domain isolation through circuit design while eliminating the need for multiple separate dies, thereby reducing manufacturing complexity and cost.
3Adaptability or versatility
If capacitive coupling is used to translate AC signals, then signal translation is achieved, but noise interference increases
Solution Approach 1:
The substrate bias circuit acts as an intermediary that actively manages the substrate voltage potential. By dynamically adjusting the substrate bias voltage, the circuit creates a stable reference that reduces noise coupling between the capacitive-coupled AC signal path and the substrate. This intermediary control mitigates the noise interference that would otherwise be introduced by the capacitive coupling mechanism.
4Adaptability or versatility
If ground domains are separated to handle voltage differences, then voltage tolerance is improved, but circuit complexity increases
Solution Approach 1:
The substrate bias circuit serves as an intermediary that actively manages the substrate voltage potential. By dynamically adjusting the substrate bias voltage, the circuit creates a stable reference that reduces noise coupling between the capacitive-coupled AC signal path and the substrate. This intermediary control mitigates the noise interference that would otherwise be introduced by the capacitive coupling mechanism.
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 efficient signal translation across ground domains with reduced circuit complexity and cost, while minimizing noise interference and protecting the integrated circuit from damage due to voltage differences.
Implementation Method 1
The first capacitor has a first terminal coupled to the first output of the transmitter and a second terminal coupled to the first input of the pulse receiver
Implementation Method 2
The substrate bias circuit has a first input coupled to the first ground terminal, a second input coupled to the second ground terminal, and an output coupled to the semiconductor substrate
Data Source
AI summary
A circuit includes a semiconductor substrate, a first ground terminal, a second ground terminal, a driver circuit, a capacitor, a receiver circuit, and a substrate bias circuit. The driver circuit is on the semiconductor substrate. The driver circuit is coupled to the first ground terminal, and has a first output and a second output. The capacitor has a first terminal coupled to the first output of the driver circuit and a second terminal. The receiver circuit is on the semiconductor substrate. The receiver circuit is coupled to the second ground terminal, and has a first input coupled to the second terminal of the capacitor, and a second input coupled to the second output of the driver circuit. The substrate bias circuit has a first input coupled to the first ground terminal, a second input coupled to the second ground terminal, and an output coupled to the semiconductor substrate.