Voltage Sensing Circuit Using Negative Bias for Stable Pumping Voltage
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Solution Overview
Problem
Conventional semiconductor memory devices face challenges in generating stable pumping voltages in low voltage environments, particularly when the power source voltage drops below 1.5 volts, leading to inadequate operation of voltage sensing circuits due to transistors falling into the triode area and failing to function as current sources.
Innovation Solution
A voltage sensing circuit that generates a negative voltage in response to reduced power source voltage, utilizing a current mirror and differential amplifiers with negative voltage sources to ensure stable current supply and accurate voltage sensing, enabling the generation of stable pumping voltages even at low power source voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power source voltage is reduced to below 1.5 volts to minimize power consumption, then power consumption is reduced, but the voltage sensing circuit cannot operate properly as transistors fall into the triode area and fail to function as current sources
Solution Approach 1:
The patent introduces a negative voltage dimension by generating a voltage lower than ground potential (VSS). This negative voltage is applied to the source terminals of transistors in the voltage sensing circuit, creating a voltage differential that allows the transistors to operate in the saturation region even when the positive supply voltage is reduced below 1.5V. The negative voltage effectively extends the voltage operating range into a new dimension below ground potential.
Solution Approach 2:
The patent changes the voltage parameter by generating a negative voltage (lower than VSS) and applying it to the source terminals of the sensing circuit transistors. This parameter change transforms the operating conditions of the transistors, enabling them to maintain saturation region operation at reduced supply voltages. The negative voltage parameter effectively compensates for the reduced positive supply voltage.
2Use of energy by moving object
If conventional voltage sensing circuits are used with reduced power source voltage, then power consumption is reduced, but the transistors fall into the triode area and fail to source current properly
Solution Approach 1:
The patent introduces a negative voltage dimension to restore current sourcing capability. By applying negative voltage to the source terminals, the voltage differential across the transistors is increased, pushing them out of the triode region and back into saturation where they can properly function as current sources, even at reduced supply voltages.
Solution Approach 2:
The patent changes the voltage parameter by introducing negative voltage to alter the transistor operating point. This parameter change ensures that the transistors maintain adequate voltage headroom across the gate-source and drain-source junctions, enabling proper current sourcing function at reduced supply voltages.
3Use of energy by moving object
If the power source voltage is reduced to meet portable device requirements, then device size and power consumption are reduced, but stable pumping voltage generation becomes difficult
Solution Approach 1:
The patent introduces negative voltage to create a stable reference point for pumping voltage generation. The negative voltage supply provides a stable lower reference that enables the voltage sensing and control circuits to maintain stable pumping voltage output even when the positive supply voltage is reduced for low-power operation.
Solution Approach 2:
The patent changes the voltage reference parameter by using negative voltage as the lower reference instead of ground. This parameter change stabilizes the pumping voltage generation by providing adequate voltage headroom for the charge pump circuitry to operate correctly at reduced supply voltages.
Data Source
AI summary
Herein, a voltage sensing circuit, which is capable of controlling a pumping voltage to be stably generated in a low voltage environment, is provided. The voltage sensing circuit includes a current mirror having first and second terminals, a first switching element configured to control current on the first terminal of the current mirror by a reference voltage, a second switching element configured to control current from the second terminal of the current mirror in response to a pumping voltage, and a third switching element configured to control current sources of the first and second switching elements to receive a negative voltage.