Intermittently Activated Bandgap Reference Circuit for Low Power DRAM
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Solution Overview
Problem
Bandgap reference circuits in low power DRAM applications consume excessive power due to constant operation, and existing methods to reduce current consumption either increase circuit complexity or have inefficient power usage.
Innovation Solution
An intermittently activated bandgap reference circuit that uses capacitors to store reference voltage and control signals to manage the activation of the bandgap reference circuit and unity gain buffer, reducing power consumption by maintaining the circuit in a low power state for extended periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bandgap reference circuit operates continuously to provide stable reference voltage, then the reference voltage stability is improved, but the power consumption increases
Solution Approach 1:
The bandgap reference circuit is activated periodically rather than continuously. A control circuit monitors the reference voltage at sampling nodes and activates the bandgap circuit only when the voltage decays below a threshold, creating a periodic activation pattern that reduces power consumption while maintaining stability.
Solution Approach 2:
The circuit uses its own output (reference voltage) to control its own operation. The control circuit monitors the reference voltage and automatically activates/deactivates the bandgap circuit based on voltage decay, making the system self-regulating without external intervention.
2Use of energy by moving object
If the bandgap reference circuit is intermittently activated to reduce power consumption, then the power consumption is reduced, but the reference voltage stability may deteriorate
Solution Approach 1:
A control circuit continuously monitors the reference voltage at sampling nodes and uses this feedback to determine when to activate the bandgap reference circuit. When voltage decay is detected below a threshold, the control circuit activates the circuit to recharge the voltage, ensuring stability is maintained despite intermittent operation.
Solution Approach 2:
The circuit anticipates voltage decay and activates the bandgap reference circuit before the reference voltage becomes unstable. The control circuit monitors voltage levels and triggers activation proactively when decay is detected, preventing instability rather than reacting to it.
3Use of energy by moving object
If a scan method with voltage divider is used to reduce bandgap circuit current, then the current consumption is reduced, but the circuit complexity increases
Solution Approach 1:
The invention extracts only the essential function of voltage sampling and monitoring from the complex scan method. Instead of using multiple comparators and switches to scan through divided voltages, the circuit simply monitors the reference voltage at sampling nodes and activates the bandgap circuit when needed, eliminating unnecessary complexity.
Solution Approach 2:
Instead of using a voltage divider to reduce the bandgap circuit's power supply voltage (as in the scan method), this invention maintains the bandgap circuit's full power supply voltage but controls its activation timing. The power reduction is achieved through temporal control rather than voltage reduction, inverting the approach of the scan method.
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
Significantly reduces electrical current consumption by maintaining the bandgap reference circuit in a low power state for substantially longer periods than it is active, achieving current savings of up to 500 or more times, depending on the implementation.
Implementation Method 1
a first capacitor coupled to the third reference voltage node; a second capacitor coupled to the fourth reference voltage node
Data Source
AI summary
A circuit for providing a reference voltage includes a bandgap reference circuit, a first unity gain buffer coupled to the bandgap reference circuit, a first switch for coupling a second reference voltage node to a third reference voltage node, a first capacitor coupled to the third reference voltage node, a second switch for coupling the third reference voltage node to a fourth reference voltage node, and a second capacitor coupled to the fourth reference voltage node, wherein during operation a fourth reference voltage at the fourth reference voltage node decays when the second capacitor discharges. A control circuit provides control signals for intermittently operating the bandgap reference circuit and for controlling the switches to recharge the second capacitor after the fourth reference voltage decays a predetermined amount.