Battery Cell Voltage Sampling with Shared Anti-Aliasing Filters
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Solution Overview
Problem
Conventional battery monitoring circuits for multiple battery cells require multiple anti-aliasing filters, leading to high latency and large circuit area, while reducing the number of filters to save space increases latency. This patent addresses the need for a solution that balances latency and area efficiency in monitoring battery cell voltages.
Innovation Solution
The proposed solution utilizes two anti-aliasing filters for a group of four battery cells, where one filter is charged while the other provides output to the analog-to-digital converter, employing a controller to sequence the states of switches and demultiplexer to ensure efficient data acquisition with reduced latency and die area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple anti-aliasing filters are used for each battery cell, then measurement precision is improved, but area of stationary object increases
Solution Approach 1:
Multiple battery cells share common circuit components including anti-aliasing filters, voltage level shifters, and multiplexers. The system combines N battery cell monitoring functions into a shared infrastructure, reducing total circuit area while maintaining measurement precision through time-multiplexed sampling.
Solution Approach 2:
The anti-aliasing filters and voltage level shifters serve multiple battery cells sequentially through multiplexing. A single filter circuit handles multiple input channels by switching between them, making the components universal rather than dedicated to single cells.
2Measurement precision
If multiple anti-aliasing filters are used for each battery cell, then measurement precision is improved, but latency increases
Solution Approach 1:
The anti-aliasing filter continuously charges from the voltage level shifter in advance, maintaining readiness. When a measurement is needed, the pre-charged filter can immediately process the signal without waiting for charging completion, reducing measurement latency.
Solution Approach 2:
While one filter is being read by the ADC, another filter simultaneously charges from the voltage level shifter. This continuous operation ensures that a charged filter is always ready for immediate measurement, eliminating idle time and reducing overall system latency.
3Area of stationary object
If the number of anti-aliasing filters is reduced to save area, then area of stationary object is improved, but latency increases
Solution Approach 1:
The system pre-charges multiple filters in parallel before they are needed for measurement. This advance preparation ensures that when measurement requests arrive, charged filters are immediately available, eliminating the latency that would otherwise result from sequential charging of reduced filter count.
Solution Approach 2:
The system dynamically switches between multiple charged filters based on measurement demands. Rather than using a single filter sequentially (which causes latency), the system maintains multiple charged filters in a ready state and dynamically selects which one to use, achieving both area efficiency and low latency.
Data Source
AI summary
A battery-operated device comprises: a first battery cell having a voltage; a second battery cell having a voltage; a first anti-aliasing filter operable to be coupled to the first battery cell; a second anti-aliasing filter operable to be coupled to the second battery cell; an analog-to-digital converter operable to be coupled to the first anti-aliasing filter during a first period of time or the second anti-aliasing filter during a second period of time different than the first period of time; and wherein the second anti-aliasing filter is charged during the first period of time and the first anti-aliasing filter is charged during the second period of time.