Grounded Capacitance Multiplier With Digital Tuning for IC Area Limits
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Solution Overview
Problem
Integrated circuits face limitations due to the constraint of low capacitance levels, making it impractical to implement electronic circuits requiring higher capacitance values, such as low-frequency filters and long-duration timing circuits.
Innovation Solution
A digitally controlled grounded capacitance multiplier circuit utilizing an operational amplifier, a digitally controlled current amplifier, and resistors to achieve a large multiplication factor in equivalent capacitance, allowing for programmability and integration of components like filters and phase-locked loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If actual capacitors with high capacitance values are used, then the capacitance level requirement is met, but the circuit area becomes too large for practical integrated circuits
Solution Approach 1:
The patent uses a capacitance multiplier circuit that creates an equivalent capacitance through active components (op-amps, transistors, and a small reference capacitor) rather than using a physical capacitor of the required capacitance value. The circuit copies the electrical behavior of a large capacitor using a small physical capacitor combined with active amplification stages, thereby achieving high equivalent capacitance without the corresponding physical area.
2Quantity of substance
If a capacitance multiplier circuit is used to achieve higher equivalent capacitance, then the capacitance level is improved, but the circuit complexity increases
Solution Approach 1:
The patent implements a digitally controlled capacitance multiplier where the multiplication factor can be dynamically adjusted through digital control signals. The circuit uses switches controlled by digital inputs to select different resistor values and transistor configurations, allowing the equivalent capacitance to be programmably tuned. This dynamic control capability adds functionality while managing complexity through standardized control interfaces.
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
Enables the creation of integrated circuits with higher capacitance values, reducing circuit size and cost while providing tunable filter parameters, effectively addressing the limitations of low capacitance in ICs.
Implementation Method 1
a first operational amplifier (op-amp) having at least a first input terminal, an output terminal, and a second input terminal that is grounded
Implementation Method 2
a digitally controlled current amplifier (DCCA) having an analog input terminal for receiving an input current, an output terminal and a digital input terminal for receiving a digital control signal. the DCCA is configured to generate an output current by amplifying the input current as a function of the digital control signal
Implementation Method 3
a reference capacitor connected in series between the input node and the first input terminal of the first op-amp
Data Source
AI summary
A digitally controlled grounded capacitance multiplier circuit system and method is disclosed. The capacitance multiplier (CM) circuit comprises an op-amp, a digitally controlled current amplifier and two resistors in addition to a reference capacitor. The CM circuit is designed using complementary metal-oxide-semiconductor (CMOS) technology. The value of the equivalent capacitance can be adjusted through digitally programming the gain of the current amplifier. The CM circuit provides a significant multiplication factor while using two active devices.