Dynamic Current Mirror Capacitance Detection for Wide-Range Low Power
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Solution Overview
Problem
Capacitance detection circuits using OTA-based structures face increased power consumption as input capacitance values rise, limiting their ability to operate efficiently over a wide dynamic range.
Innovation Solution
A capacitance detection circuit with an OTA-FREE structure utilizing a dynamic current mirror, comprising a first dynamic current mirror circuit with a reference capacitor and an input capacitor, an oscillator circuit, and a power circuit independent of supply voltage, allowing for capacitance measurement across a wide dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OTA-based capacitance detection circuit is used, then capacitance detection capability is achieved, but power consumption increases as input capacitance value increases
Solution Approach 1:
The patent removes the operational transconductance amplifier (OTA) from the capacitance detection circuit, replacing it with a dynamic current mirror circuit. This extraction of the OTA eliminates the primary source of power consumption that scales with input capacitance value, while preserving the capacitance detection functionality through alternative circuit mechanisms.
Solution Approach 2:
The patent substitutes the electronic amplifier-based OTA system with a current mirror-based system that operates on different principles. The dynamic current mirror uses current copying and voltage mirroring mechanisms instead of transconductance amplification, fundamentally changing the operational mechanism to achieve lower power consumption.
2Measurement precision
If OTA-based capacitance detection circuit is used, then capacitance detection is enabled, but circuit area increases
Solution Approach 1:
By removing the OTA component from the circuit architecture, the patent eliminates the significant area that an operational transconductance amplifier would occupy. The replacement dynamic current mirror circuit uses transistors and capacitors that can be implemented with smaller footprint while achieving the same detection function.
3Use of energy by moving object
If dynamic current mirror circuit is used, then power consumption is reduced, but circuit complexity changes
Solution Approach 1:
The patent employs a dynamic current mirror circuit that operates in different phases (charging phase and discharging phase) controlled by clock signals. The circuit dynamically switches between reference capacitor charging and input capacitor charging operations, enabling low-power operation through timed activation of different circuit paths.
Solution Approach 2:
The dynamic current mirror circuit operates periodically with alternating phases controlled by clock signals. During one phase, the reference capacitor is charged; during another phase, the input capacitor is charged. This periodic operation allows the circuit to maintain detection capability while reducing average power consumption compared to continuous operation.
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 low-power capacitance detection with improved area efficiency and independent reference current generation, reducing power consumption and enhancing dynamic range capabilities.
Implementation Method 1
a first dynamic current mirror circuit including a reference capacitor connected in series with a first transistor and an input capacitor connected in series with a second transistor, and an oscillator circuit connected to an output node of the first dynamic current mirror circuit
Implementation Method 2
an oscillator circuit connected to an output node of the first dynamic current mirror circuit and configured to charge an integration capacitance using current output from the first dynamic current mirror circuit
Data Source
AI summary
A capacitance detection circuit using a dynamic current mirror includes a first dynamic current mirror circuit including a reference capacitor connected in series with a first transistor and an input capacitor connected in series with a second transistor, and an oscillator circuit connected to an output node of the first dynamic current mirror circuit and configured to charge an integration capacitance using current output from the first dynamic current mirror circuit. The amount of change in voltage at a first node positioned between a source of the first transistor and the reference capacitor may be identical to the amount of change in voltage at a second node positioned between a source of the second transistor and the input capacitor.