Bandgap Reference Clamp Circuit for Low-Power Suspend Mode

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Solution Overview

Problem

Conventional bandgap reference voltage source circuits consume significant power in low power modes, reducing the standby time of portable electronic devices, and it is challenging to shut down the bandgap reference voltage source without significant voltage variation affecting the source voltage.

Innovation Solution

A bandgap reference circuit that includes a reference generator, clamp circuit, regulator, and digital core, where the digital core controls the multiplexer to connect the reference voltage to the regulator and powers off the bandgap reference voltage source in low power modes, using diodes as resistors to reduce circuit area and employing calibration to set a stable source voltage with minimal variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the bandgap reference voltage source is continuously operated to provide stable reference voltage, then the source voltage stability is improved, but the power consumption increases significantly in low power modes

Engineering Contradiction:

Improvesource voltage stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The bandgap reference voltage source is operated periodically rather than continuously. A mode control circuit switches the bandgap reference between active and standby states based on system power mode. In low power modes, the bandgap reference is placed in standby with dramatically reduced current consumption (nanoampere range), while still maintaining sufficient reference voltage stability through capacitor holding and optimized circuit design.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the operating state of the bandgap reference voltage source based on power mode requirements. The mode control circuit detects system state and dynamically switches between full operation (normal mode) and reduced operation (low power mode), optimizing the balance between voltage stability and power consumption in real-time.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If the bandgap reference voltage source is shut down to reduce power consumption, then the power consumption is reduced, but the source voltage varies significantly exceeding allowable range

Engineering Contradiction:

Improvepower consumptionVSAvoidsource voltage stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

A mode control circuit acts as an intermediary between the bandgap reference voltage source and the rest of the system. This control circuit manages the transition between active and standby states, ensuring that when the bandgap reference is shut down or placed in standby, the system switches to alternative voltage sources or uses stored energy in capacitors to maintain source voltage within allowable ranges.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system prepares for voltage variations by implementing beforehand cushioning measures. When the bandgap reference is about to be shut down for low power mode, capacitors are charged to hold the reference voltage, and alternative voltage paths are pre-configured to prevent significant source voltage variation when the bandgap reference stops operating.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If conventional power source circuits are used with bandgap reference voltage source, then the source voltage is maintained, but the standby time of portable devices is shortened

Engineering Contradiction:

Improvesource voltageVSAvoidstandby time

Core Design Contradiction:

Stability of the object's compositionVSDuration of action of moving object

Solution Approach 1:

The bandgap reference voltage source operates periodically rather than continuously during standby periods. The mode control circuit detects when the system is in standby or low power mode and switches the bandgap reference to a ultra-low power standby state, reducing current consumption to nanoampere levels while maintaining sufficient voltage stability through optimized circuit design and capacitor holding.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The operating parameters of the bandgap reference voltage source are changed based on system state. In standby mode, the reference current is reduced to extremely low levels (nanoampere range) while maintaining acceptable voltage stability. This parameter change allows the system to extend standby time significantly while still providing adequate reference voltage when needed.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10915122B2Sensor chip using having low power consumption

Publication Date: 2021.02.09 PIXART IMAGING INC

AI summary

A bandgap reference circuit including a clamp circuit is provided. The bandgap reference circuit performs the calibration only for one time in a normal mode to store a control code of a reference generator of the clamp circuit. In a suspend mode, the control code is used for controlling the reference generator to cause the clamp circuit to provide a desired source voltage, and a bandgap reference voltage source is shut down to reduce the power consumption.