Single-Supply Level Shifter Circuit Using Multi-Stage Voltage Translation
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Solution Overview
Problem
Conventional level shifter circuits using a single voltage supply suffer from high leakage currents and limited operating speed, especially when the difference between the voltage supply and input voltage exceeds the threshold voltage, which restricts their use in applications with broad input and output voltage ranges.
Innovation Solution
A level shifter circuit design that includes a voltage translation stage, a driver stage, and a comparison stage, utilizing a combination of PMOS and NMOS transistors to manage voltage levels and minimize leakage, allowing operation with a single voltage supply without additional power routing resources, thereby reducing congestion and enabling faster operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional level shifter circuits use a single voltage supply to reduce routing complexity, then routing congestion is reduced, but leakage current increases significantly when voltage difference exceeds threshold voltage
Solution Approach 1:
The level shifter circuit is divided into multiple stages: a first level shifter stage that performs initial voltage level shifting, and a second level shifter stage that performs additional voltage level shifting. This segmentation allows the circuit to handle broader voltage ranges while maintaining lower leakage currents by breaking down the voltage translation into smaller, more manageable steps, where each stage operates within optimal voltage differences.
Solution Approach 2:
The invention introduces an intermediate voltage level through the multi-stage architecture. The first level shifter stage produces an intermediate voltage that serves as input to the second level shifter stage. This intermediary approach prevents direct large voltage differences across single transistors, thereby reducing leakage current while still achieving the desired overall voltage level shifting from the single voltage supply domain.
2Ease of operation
If conventional level shifter circuits use a single voltage supply to simplify power routing, then placement restrictions are reduced, but operating speed is limited
Solution Approach 1:
The multi-stage level shifter architecture segments the voltage translation function into multiple faster-switching stages. Each stage operates with smaller voltage swings and can be optimized for speed, collectively achieving faster overall operation compared to a single-stage design constrained by large voltage differences and single voltage supply limitations.
Solution Approach 2:
The circuit employs dynamic gating control where enable signals dynamically activate or deactivate specific transistor pairs in each stage based on the required voltage level shifting. This dynamic operation allows the circuit to adapt its switching behavior to optimize speed for different operating conditions while maintaining placement flexibility from single voltage supply operation.
3Object-generated harmful factors
If dual voltage supplies are used in level shifter circuits to reduce leakage current, then leakage is minimized, but routing tracks increase leading to congestion
Solution Approach 1:
The invention merges the function of dual voltage supplies into a single voltage supply architecture. By using multiple level shifter stages with carefully designed transistor configurations and enable signals, the circuit achieves leakage current reduction normally associated with dual voltage supplies while maintaining single voltage supply routing simplicity, thus avoiding additional routing tracks and congestion.
Solution Approach 2:
The multi-stage architecture introduces intermediate voltage levels and intermediate transistor states that act as mediators to control leakage current flow. Each stage uses enable signals to control the activation of transistor pairs, creating intermediate control points that manage leakage without requiring separate high and low voltage supply rails, thereby avoiding the routing complexity of dual voltage supplies.
Data Source
AI summary
A single supply level shifter circuit for shifting the voltage level of an input voltage includes a voltage translation stage and a driver stage. The voltage translation stage receives the input voltage and a voltage supply and generates a first voltage. When a magnitude of the input voltage is LOW, the first voltage is LOW. The first voltage is provided to the driver stage, which inverts the first voltage to generate an output voltage that is at a voltage supply (Vdd) level, thereby level shifting the input voltage.