Fractional Bandgap Reference Voltage Generator for Low Supply Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bandgap reference voltage generator circuits face challenges in operating at low supply voltages below 1.8 Volts, particularly in generating sub-bandgap reference voltages efficiently while minimizing power consumption and integrated circuit area occupation.
Innovation Solution
A fractional bandgap reference voltage generator circuit is designed with a current generator producing PTAT and CTAT currents, a voltage divider, and a resistive circuit to produce a temperature-independent reference voltage that is a fraction of the bandgap voltage, utilizing a reduced number of resistors to minimize area occupation and support low power operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional bandgap reference voltage generator circuits are used, then temperature independent reference voltage can be generated, but the circuit cannot operate at supply voltages below 1.8 Volts
Solution Approach 1:
The circuit is segmented into multiple operational modes with different topologies. A first circuit topology operates when supply voltage exceeds a threshold (providing temperature compensation), while a second topology operates when supply voltage is below the threshold (providing direct voltage division). This segmentation allows the circuit to adapt to different voltage conditions while maintaining reliable reference voltage generation.
Solution Approach 2:
The circuit dynamically switches between two different topologies based on the supply voltage level. A voltage detection mechanism monitors the supply voltage and controls a switch to select the appropriate topology, enabling the circuit to maintain proper operation across a wide voltage range from 0.5V to above 1.8V.
2Use of energy by moving object
If large resistance value resistors are used to achieve low power consumption, then power consumption is reduced, but integrated circuit area occupation increases
Solution Approach 1:
The circuit changes resistance values dynamically based on operating conditions. During low-power mode, high resistance values are used to minimize current consumption. During fast-start mode, low resistance values are used to enable rapid charging of capacitors and quick establishment of reference voltage. This parameter change allows optimization of both power consumption and startup performance without permanently occupying large area.
Solution Approach 2:
The circuit employs periodic switching between different operational states. A control signal periodically enables fast-start mode (with low resistance) for brief intervals to charge capacitors, then switches to low-power mode (with high resistance) for extended periods to minimize current consumption. This periodic action allows the circuit to achieve low average power consumption while maintaining capability for rapid voltage establishment when needed.
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 solution enables efficient generation of sub-bandgap reference voltages at low supply voltages, achieving low power consumption and reduced integrated circuit area usage, with the ability to operate at supply voltages as low as 0.5 Volts, while maintaining temperature independence.
Implementation Method 1
a current generator circuit configured to generate a current that is proportional to absolute temperature (PTAT) and a voltage that is complementary to absolute temperature (CTAT)
Implementation Method 2
a current generator circuit configured to generate a current that is proportional to absolute temperature (PTAT) and a voltage that is complementary to absolute temperature (CTAT)
Data Source
AI summary
A reference voltage generator circuit includes a circuit that generates a complementary to absolute temperature (CTAT) voltage and a proportional to absolute temperature (PTAT) current. An output current circuit generates, from the PTAT current, a sink PTAT current sunk from a first node and a source PTAT current sourced to a second node, wherein the sink and source PTAT currents are equal. A resistor is directly connected between the first node and the second node. A divider circuit divides the CTAT voltage to generate a divided CTAT voltage applied to the first node. A voltage at the second node is a fractional bandgap reference voltage equal to a sum of the divided CTAT voltage and a voltage drop across the resistor that is proportional to a resistor current equal to the sink and source PTAT currents.