Transconductance Capacitance Multiplier for Low-Voltage Decoupling
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Solution Overview
Problem
Conventional capacitance multiplier circuits are unsuitable for low voltage applications due to voltage drop, require high impedance, and consume large amounts of power, making them inefficient for integrated circuits.
Innovation Solution
The implementation of a capacitance multiplier circuitry that includes a capacitor, an adjustable resistance, and a transconductance circuit, allowing for a significant increase in capacitance value without voltage drop or high power consumption, using a configuration that includes transistors, resistors, and optional diode-connected transistors or current sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If decoupling capacitance is implemented as a capacitance multiplier circuit to minimize circuit area, then circuit area is reduced, but conventional capacitance multiplier circuits consume large amounts of power
Solution Approach 1:
The patent changes the operating parameters of the capacitance multiplier circuit by using a transconductance circuit with high gain to achieve low power consumption. The circuit operates at supply voltages of 1.8V or lower, and the power consumption is reduced to approximately 100nW or less by optimizing the transconductance parameters and using a capacitor value of about 100fF, which is significantly lower than conventional circuits requiring large capacitor values and high power.
2Quantity of substance
If conventional capacitance multiplier circuits are used to provide large capacitance, then capacitance value is increased, but voltage drop occurs from input to output making them unsuitable for low voltage applications
Solution Approach 1:
The patent replaces the conventional voltage-based capacitance multiplication mechanism with a transconductance-based mechanism. Instead of using voltage drops across resistors to multiply capacitance, the circuit uses a transconductance amplifier with high gain (gm) to achieve capacitance multiplication through current feedback, eliminating the voltage drop problem and enabling operation at low supply voltages of 1.8V or lower.
3Quantity of substance
If conventional capacitance multiplier circuits are used to achieve large capacitance values, then capacitance is increased, but the powered circuit is required to have high impedance
Solution Approach 1:
The patent inverts the conventional approach by using a transconductance circuit that actively drives the output rather than passively multiplying capacitance. The transconductance amplifier provides low output impedance by actively sourcing and sinking current, allowing the capacitance multiplier to drive low-impedance loads and connect to power supply lines with low impedance, thus removing the high impedance requirement of conventional circuits.
4Object-affected harmful factors
If decoupling capacitance with greater capacitance values is used to provide better noise suppression, then noise suppression is improved, but circuit area increases
Solution Approach 1:
The patent changes the fundamental parameters of the decoupling capacitance implementation by using a small physical capacitor (about 100fF) combined with a high-gain transconductance circuit to achieve an effective capacitance of several nanofarads. This parameter transformation allows the circuit to provide strong noise suppression equivalent to large capacitors while occupying minimal circuit area, as the physical capacitor size is determined by the transistor gate area rather than the capacitance value itself.
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
This configuration provides a capacitance value that is over a hundred times greater than the capacitor's original value, enabling effective noise suppression on power supply lines without increasing circuit area or power consumption, suitable for low voltage applications.
Implementation Method 1
a transconductance circuit coupled to the capacitor and the adjustable resistance
Implementation Method 2
a capacitor having a first terminal coupled to the power supply line and having a second terminal
Implementation Method 3
an adjustable resistance having a first terminal coupled to the second terminal of the capacitor and having a second terminal
Data Source
AI summary
An integrated circuit may include one or more circuits coupled to capacitance multiplier circuitry. The capacitance multiplier circuitry may include a capacitor, fixed and tunable resistances, and a transconductance circuit. The tunable resistance can be adjusted to control the overall capacitance of the capacitance multiplier circuitry. The transconductance circuit may include a transistor having a drain terminal coupled to a first electrical component and a source terminal coupled to a second electrical component. The first electrical component may be a diode-connected transistor, a direct shorting wire, a resistor, an inductor, or a current source. The second electrical component may be a current source, a direct shorting wire, a resistor, an inductor, or another diode-connected device. Configured in this way, the capacitance multiplier circuitry can provide a large adjustable amount of capacitance without a voltage drop and without consuming a large amount of power.