Capacitive Puff Detection Circuit With Leakage Current Compensation
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Solution Overview
Problem
Electronic vaping apparatuses experience detection errors and abnormalities at elevated temperatures, leading to non-triggering or delayed triggering issues in puff detection circuits.
Innovation Solution
A compensation device is introduced in the puff detection circuitry, comprising a first signal generator and a second signal generator, with a compensation device providing a leaking current path to mitigate errors caused by temperature changes, using a semiconductor p-n junction and an ESD diode to equalize leakage current variations, forming a dual slope ADC configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ESD diode is used to provide electrostatic discharge protection in the detection circuit, then the circuit reliability is improved, but the leakage current varies with temperature causing detection errors at elevated temperatures
Solution Approach 1:
A compensation device is introduced as an intermediary element between the ESD diode and the detection circuit. This compensation device generates a compensating current that counteracts the temperature-dependent leakage current of the ESD diode, thereby maintaining detection accuracy while preserving the protective function of the ESD diode.
Solution Approach 2:
The compensation device changes its operational parameters (current output) in response to temperature variations. By monitoring temperature changes and adjusting the compensating current accordingly, the system maintains constant detection performance across different temperature conditions despite the ESD diode's varying leakage characteristics.
2Adaptability or versatility
If the puff detection circuit operates at elevated temperatures to match vaping device operating conditions, then the device can function in its intended environment, but detection errors and abnormalities occur
Solution Approach 1:
The compensation device provides beforehand cushioning by pre-compensating for the expected temperature-dependent leakage current variations. Before temperature changes cause detection errors, the compensation device adjusts its output to counteract the anticipated leakage current changes, ensuring continuous reliable operation across the full temperature range.
3Measurement precision
If the leakage current of the ESD diode is reduced to improve detection accuracy, then the detection precision is improved, but the ESD protection capability is weakened
Solution Approach 1:
The system segments the current paths by separating the protection function (ESD diode) from the detection function (detection circuit). The ESD diode maintains its full protection capability while the compensation device independently manages the leakage current issue, allowing both functions to operate optimally without compromising either protection or precision.
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 provides more predictable and stable performance at elevated temperatures, reducing detection errors and ensuring accurate puff detection, thereby enhancing vaping operations.
Implementation Method 1
the compensation device is configured to provide a leaking current path so that a minor portion of the first current is to flow into the compensation device as a compensational leakage current during charging cycles of the first charging circuit portion to mitigate errors arising from a change in leakage current of the ESD diode due to a change in operational temperature
Implementation Method 2
The ESD diode has a leaking-current-versus-temperature trend. The compensation device may have a leaking-current-versus-temperature trend following the leaking-current-versus-temperature trend of the ESD diode in the elevated operation temperature range.
Implementation Method 3
a first charging-and-discharging circuit which is configured to repeatedly charge and discharge the first capacitor whereby a first train of pulses having a first frequency is generated
Data Source
AI summary
A puff detection device (10) comprising a capacitive puff sensor (C2), a detection signal generator (140) for connection with the puff sensor (C2) and having an ESD diode (D2) at an input node (IN2), and a reference signal generator (120) which is configured to generate a train of reference pulses (CKI) having a reference frequency and comprises a reference capacitor (C1). The reference signal generator (120) includes a compensation device (D1) which is configured to provide a leakage current path at a charging node (IN1) of the reference capacitor (C1).