Source Plate Discharge Circuit Using Avalanche BJT Switching
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Solution Overview
Problem
Existing memory devices face challenges in quickly dropping voltages at source plates, particularly during erase operations or in response to power issues, due to the slow discharge process and potential damage from high current usage with traditional HV NMOS devices.
Innovation Solution
The use of high-voltage bipolar junction transistor (BJT) devices operating in avalanche mode to rapidly discharge currents at source plates without the need for ballast resistors, allowing for quicker voltage drops and reduced space consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional HV NMOS devices are used to discharge source plate voltage, then the discharge process is simple to implement, but the discharge speed is slow (hundreds of microseconds) and high current may damage the devices
Solution Approach 1:
The patent changes the operating parameters of the BJT device by applying a reverse bias voltage across the collector-base junction to induce avalanche breakdown. This parameter change enables the BJT to enter avalanche mode, where it can rapidly discharge high currents without damage, achieving discharge speeds in tens of microseconds while maintaining device reliability through controlled breakdown operation.
Solution Approach 2:
The patent introduces a control circuit as an intermediary that manages the BJT device operation. This control circuit applies the reverse bias voltage to initiate avalanche breakdown and monitors/limits the current to prevent device damage. The intermediary control mechanism enables safe, rapid discharge by mediating between the high current discharge requirement and the device protection requirement.
2Area of stationary object
If traditional discharge methods are used, then device simplicity is maintained, but space consumption is high due to the need for ballast resistors and slower discharge process
Solution Approach 1:
The patent extracts and eliminates the ballast resistor component from the discharge circuit by using the BJT device in avalanche mode. The BJT's inherent current-limiting characteristics during avalanche breakdown replace the function previously performed by external ballast resistors, reducing the circuit's space requirements while simultaneously improving discharge speed to tens of microseconds.
Solution Approach 2:
By changing the BJT's operating state to avalanche mode through reverse bias application, the patent achieves rapid discharge without requiring external current-limiting components. This parameter change enables the device to self-regulate current during discharge, eliminating the need for space-consuming ballast resistors while achieving fast discharge speeds.
3Productivity
If BJT devices operate in avalanche mode, then discharge speed increases to tens of microseconds and space consumption decreases, but the operation mode becomes more complex
Solution Approach 1:
The control circuit serves as an intermediary that simplifies the overall system by automating the complex avalanche mode control. It automatically applies the reverse bias voltage, monitors discharge progress, and manages the BJT operation, thereby hiding the complexity from the user and enabling high productivity through automated, rapid discharge operations in tens of microseconds.
Solution Approach 2:
The BJT device in avalanche mode exhibits self-regulating characteristics where the breakdown process naturally limits current and controls the discharge. This self-service behavior reduces the complexity of external control circuits, as the device automatically manages its own operation during avalanche breakdown, enabling fast discharge with minimal external intervention.
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
Enables faster execution of memory operations, quicker response to power issues, and reduced risk of damage, with BJT devices discharging voltage in tens of microseconds compared to hundreds of microseconds with traditional methods.
Implementation Method 1
high-voltage bipolar junction transistor (BJT) devices operating in avalanche mode to rapidly discharge currents at source plates
Data Source
AI summary
Memory systems and devices with source plate discharge circuits (and associated methods) are described herein. In one embodiment, a memory device includes (a) a plurality of memory cells, (b) a source plate electrically coupled to the plurality of memory cells, and (c) a discharge circuit. The discharge circuit can include a bipolar junction transistor device electrically coupled to the source plate and configured to drop a voltage at the source plate by, for example, discharging current through the bipolar junction transistor device. In some embodiments, the bipolar junction transistor device can be activated using a low-voltage switch or a high-voltage switch electrically coupled to the bipolar junction transistor. In these and other embodiments, the bipolar junction transistor device can operate in an avalanche mode while discharging current to drop the voltage at the source plate.