Offset-Cancelling Amplifier Timing for Particle Sensor Precision
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Solution Overview
Problem
Conventional particle sensors face challenges in accurately detecting particles due to large offset components from light sources, which require significant area and power consumption for offset cancellation using methods like correlated double sampling or digital-to-analog conversion.
Innovation Solution
An amplifier and sensor system with an offset cancelling circuit that controls amplification and activation based on control signals, utilizing an ADC to convert signals into digital form and a control circuit to generate offset control signals, reducing power consumption and area requirements by only activating the offset cancelling circuit when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correlated double sampling or digital-to-analog converter is used to cancel offset component, then offset cancellation is achieved, but area and power consumption increase significantly
Solution Approach 1:
The patent extracts the offset cancellation function from the main signal processing path by using a separate offset storage node that captures and stores offset components independently. This allows offset removal without requiring large DAC circuits or complex correlated double sampling hardware, thus reducing area while maintaining precision.
Solution Approach 2:
The patent changes the operational parameters of the amplifier by controlling the timing of offset cancellation through control signals. The offset is cancelled only during specific time periods when the light source is off, rather than continuously, which reduces power consumption while maintaining measurement accuracy when needed.
2Measurement precision
If digital-to-analog converter is used to remove offset component, then offset removal is achieved, but power consumption and area increase due to DAC requirements
Solution Approach 1:
The patent implements periodic offset cancellation by controlling the offset cancelling circuit to operate only during specific time intervals when the light source is turned off. This periodic operation rather than continuous operation significantly reduces power consumption while maintaining the ability to remove offset components accurately when measurements are taken.
Solution Approach 2:
The patent extracts the offset component into a separate storage node and processes it independently from the main signal path. This allows offset removal without requiring power-intensive DAC circuits, as the offset is handled through simpler switching and storage operations that consume minimal power.
3Measurement precision
If offset cancelling circuit is always activated, then offset cancellation is continuous, but power consumption increases
Solution Approach 1:
The patent employs periodic activation of the offset cancelling circuit controlled by control signals that enable offset cancellation only during specific time windows when the light source is off. This periodic operation maintains offset cancellation quality when needed while avoiding continuous power consumption, achieving an optimal balance between precision and energy efficiency.
Solution Approach 2:
The patent makes the offset cancelling circuit dynamic by controlling its activation state through control signals rather than keeping it permanently on. The circuit transitions between active and inactive states based on operational requirements, allowing the system to maintain measurement precision when needed while minimizing power consumption during normal operation.
Data Source
AI summary
An amplifier includes an amplification circuit including an input circuit receiving an input signal and configured to output an output signal by amplifying the input signal; and an offset cancelling circuit configured to cancel offset by controlling the input circuit according to activation control signal and offset control signal, wherein the offset cancelling circuit cancels the offset according to the offset control signal after the activation control signal is activated.