Clocked Amplifier Bandgap Reference for Ultra-Low Power
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Solution Overview
Problem
Conventional bandgap reference circuits consume high power due to the limitations of operational amplifiers, which restrict the reduction of settling time and thus the average current drawn, making them inefficient for energy-harvesting and wearable devices.
Innovation Solution
A clocked operational amplifier that samples inputs based on a clock pulse, holds the output until the next pulse, and uses a charge pump to adjust the output voltage, reducing power consumption by eliminating the need for continuous operation of the bandgap core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional operational amplifier is used in the bandgap reference circuit, then the circuit can maintain a stable output voltage, but the power consumption is high due to the inability to reduce settling time
Solution Approach 1:
The patent applies periodic action by using a clock signal to periodically enable and disable the operational amplifier. The amplifier operates in discrete time intervals synchronized with the clock signal, performing comparison operations only when needed rather than continuously. This periodic operation dramatically reduces average power consumption while maintaining the ability to achieve stable output voltage when the amplifier is active, resolving the contradiction between low power consumption and settling time stability.
2Reliability
If the operational amplifier operates continuously to maintain stability, then settling time is sufficient, but average current draw increases
Solution Approach 1:
The patent applies dynamics by transitioning the operational amplifier from a static continuous-operation mode to a dynamic periodic-operation mode. The amplifier's operation is modulated by the clock signal, allowing it to be active only during specific time intervals when voltage comparison is required. This dynamic operation maintains output stability during active periods while reducing average current draw overall, as the amplifier is powered down during inactive periods.
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 clocked operational amplifier achieves an average current draw of 3 nA, making the bandgap reference 33.3 times more power-efficient than conventional designs, suitable for low-power applications.
Implementation Method 1
a clocked comparator to compare a first voltage to a second voltage when a clock signal pulses and output a comparison signal based on the comparison
Implementation Method 2
a monoshot to, when the comparison signal is a first signal, output a first pulse and, when the comparison signal is a second signal, output a second pulse
Implementation Method 3
a charge pump to increase an output voltage when the monoshot outputs the first pulse, decrease the output voltage when the monoshot outputs the second pulse, and hold the output voltage when the monoshot is not outputting a pulse
Data Source
AI summary
Methods and apparatus providing an ultra-low power bandgap reference using a clocked amplifier are disclosed. An example apparatus includes a clocked comparator to compare a first voltage to a second voltage when a clock signal pulses and output a comparison signal based on the comparison, the comparison signal being (A) a first signal when the first voltage is higher than the second voltage and (B) a second signal when the first voltage is lower than the second voltage; a monoshot to when the comparison signal is a first signal, output a first pulse; and when the comparison signal is a second signal, output a second pulse; and a charge pump to increase an output voltage when the monoshot outputs the first pulse; decrease the output voltage when the monoshot outputs the second pulse; and hold the output voltage when the monoshot is not outputting a pulse.