Single-Ended Sense Amplifier Virtual Supply Adaptation
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Solution Overview
Problem
Single-ended sense amplifiers in low-voltage designs for edge-computing systems face challenges with PVT variations, leading to high minimum supply voltage requirements and significant standby leakage, particularly when reading '0', which degrades operation speed and reliability.
Innovation Solution
A single-ended sense amplifier design featuring a virtual-supply-voltage-adapted inverter circuit and a voltage-level converter with a virtual-supply-voltage-adaption circuit, allowing for mutual adaptation of virtual supply voltages between two nodes to improve reliability, speed, and reduce standby leakage, using a cascade configuration of PMOS and NMOS transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a static inverter is used as a sense amplifier with adjustable trip point, then the logic value determination is improved, but the minimum supply voltage is limited due to sensitivity to PVT variations
Solution Approach 1:
The patent introduces a virtual supply voltage node as an intermediary between the actual supply voltage and the inverter circuit. This virtual node acts as a buffer that isolates the inverter from direct PVT variations while still enabling logic value determination. The virtual supply voltage is generated through a separate circuit that compensates for PVT effects, allowing the inverter to operate with lower actual supply voltage while maintaining measurement precision.
2Measurement precision
If a differential sense amplifier with fixed reference voltage is used, then the sensing accuracy is improved, but off-chip calibration is required under severe PVT variations
Solution Approach 1:
The patent implements a self-calibrating mechanism where the virtual supply voltage circuit automatically adjusts to compensate for PVT variations without requiring external calibration. The circuit uses feedback from the actual operating conditions to self-regulate the virtual supply voltage, eliminating the need for off-chip calibration while maintaining sensing accuracy under severe PVT variations.
3Speed
If the virtual supply voltage adaptation is performed by increasing PMOS device size or decreasing capacitor capacitance, then the adaptation speed is improved, but the circuit area and leakage current increase
Solution Approach 1:
The patent employs dynamic control of the virtual supply voltage adaptation process. Instead of using fixed large PMOS devices or small capacitors that cause leakage, the circuit dynamically adjusts the adaptation rate based on the actual voltage deviation and timing requirements. This dynamic approach allows fast adaptation when needed while entering low-leakage states when the virtual supply voltage is stable, thereby reducing standby leakage without sacrificing adaptation speed.
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 design achieves higher operation reliability, faster operation speed, lower minimum supply voltage, and reduced standby leakage by enabling effective charge replenishment and leakage reduction during data read operations, particularly for '0' readings, thus enhancing overall circuit performance.
Implementation Method 1
the capacitor 110 in stage 11 and the output SAO of the sense amplifier to VDD
Implementation Method 2
The turned-on device 112 induces a charge-sharing effect between the virtual power supply node and node O11
Data Source
AI summary
A single-ended sense amplifier includes a virtual-supply voltage-adapted (VVDD-adapted) inverter circuit, a virtual-supply voltage-adapted (VVDD-adapted) voltage-level converter circuit (VLC), and a virtual-supply-voltage-adaptation circuit (VSVA). The single-ended sense amplifier receives a data signal input, a sensing-operation-enabling signal input, and a pre-charging control signal input to generate a final amplified signal output. There are a first virtual-supply node and a second virtual-supply node in the VVDD-adapted inverter circuit. There is a third virtual-supply node in the VVDD-adapted VLC. The VSVA connects both the first and third virtual supply voltage nodes. The output end of the virtual-supply voltage-adapted inverter circuit connects to the input end of the VVDD-adapted VLC.