Single-Supply Level Shifter With Programmable Bi-Directional Translation
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Solution Overview
Problem
Conventional level-shifter circuits require multiple supply voltages, causing power routing congestion and are limited by their unidirectional operation, slow speed, and high implementation area, especially in dynamically scalable SoCs where supply voltages are unknown.
Innovation Solution
A programmable single-supply level-shifter circuit using a combination of field-effect transistors and diode-connected FETs, with a mode select signal to configure the circuit for optimal operation in either high-to-low or low-to-high voltage translations, minimizing power consumption and implementation area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-supply level-shifter circuits are used to shift supply voltage between voltage domains, then voltage translation function is achieved, but power routing congestion occurs due to need for multiple supply voltages at each receiver
Solution Approach 1:
The level-shifter circuit is designed to operate with a single supply voltage from the receiver's voltage domain, eliminating the need for multiple supply voltages. The circuit uses the receiver's local supply voltage (VDD2) for both the second inverter and the diode-connected FET, making the circuit universal and adaptable to any voltage domain without requiring additional power routing infrastructure.
Solution Approach 2:
The diode-connected FET acts as an intermediary element that enables voltage translation using only the receiver's supply voltage. It provides the necessary voltage level shifting function by leveraging the receiver's local power domain, thereby avoiding the need for direct connection to the transmitter's supply voltage domain.
2Device complexity
If existing single-supply level-shifter circuits are used, then power routing congestion is reduced, but operating range is limited and speed is slow
Solution Approach 1:
The circuit incorporates a mode select signal that dynamically configures the circuit operation based on the voltage translation direction required. This dynamic adaptability allows the circuit to optimize its performance for either high-to-low or low-to-high voltage translation, thereby improving operating speed across a wider range of conditions compared to fixed single-supply designs.
Solution Approach 2:
The circuit changes its operational parameters based on the mode select signal, adjusting the configuration of FETs to optimize performance for different voltage translation scenarios. This parameter adaptation enables the circuit to maintain high speed operation across varying operating conditions while still using only a single supply voltage.
3Use of energy by moving object
If existing single-supply level-shifter circuits are used, then power consumption is reduced, but implementation area is intensive
Solution Approach 1:
The circuit merges the functionality of multiple FETs into a compact configuration where the diode-connected FET serves dual purposes: establishing the bias voltage for the first inverter and participating in the voltage translation process. This merging of functions reduces the overall implementation area while maintaining low power consumption characteristics.
Solution Approach 2:
The level-shifter circuit achieves bi-directional voltage translation capability using a single supply voltage, making the circuit highly versatile. This multi-functionality allows the same circuit structure to handle both high-to-low and low-to-high voltage translations efficiently, reducing the need for separate circuits and thereby minimizing total implementation area.
4Adaptability or versatility
If mode select configuration is implemented, then bi-directional operation is achieved, but circuit complexity increases
Solution Approach 1:
The mode select signal dynamically reconfigures the circuit's operation to accommodate bi-directional voltage translation. Rather than requiring physically different circuits for each direction, the same hardware is dynamically adapted through the mode select signal, achieving versatility without proportionally increasing physical circuit complexity.
Data Source
AI summary
In an example implementation, a level-shifter circuit in an integrated circuit (IC) includes a plurality field-effect transistors (FETs) coupled to provide: a first inverter having an input port configured to receive an input signal having a first supply voltage, an output port, and a bias port; a second inverter having an input port coupled to the output port of the first inverter, an output port, and a bias port coupled to a second supply voltage; a diode-connected FET coupled between the second supply voltage and the bias port of the first inverter; a first FET in parallel with the diode-connected FET having a gate coupled to the output of the second inverter; and a second FET in parallel with the diode-connected FET and the first FET having a gate configured to receive a mode select signal.