Charge-Coupled Amplifier Bias Control Without Large RC Elements
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Solution Overview
Problem
Existing signal processing circuits face challenges in implementing low noise amplification for very small signals in low bandwidth applications on silicon chips, as they require impractically large capacitors for AC coupling and high resistors for DC voltage definition, which are not feasible for silicon chip implementation.
Innovation Solution
The use of quantum gate tunneling in semiconductor circuits to define the DC state of charge-coupled amplifiers, allowing for bipolar tunneling currents and controlled common mode voltages without additional elements, enabling low noise amplification without large capacitors or resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If AC coupling capacitors are used in amplifier circuits to handle low frequency signals, then the circuit can process signals from 1 Hz to 500 Hz, but the capacitor value must be impractically large (13 mF) which cannot be implemented on silicon chips
Solution Approach 1:
The patent replaces the traditional mechanical/electrical AC coupling capacitor with a quantum tunneling-based circuit mechanism. The tunneling current through the gate oxide naturally provides the coupling function without requiring large physical capacitance values, enabling low-frequency signal processing on integrated circuits.
Solution Approach 2:
The patent changes the operating parameters by utilizing quantum tunneling current characteristics to establish a DC state that enables low-frequency operation. This allows the circuit to achieve the same signal coupling effect with dramatically reduced component values suitable for silicon chip implementation.
2Reliability
If large value resistors are used to define DC voltage in charge-coupled amplifiers, then the DC state can be established, but the resistor values become impractically high and cannot be implemented on silicon chips
Solution Approach 1:
The patent replaces the traditional high-value resistor used for DC bias definition with a quantum tunneling current mechanism. The tunneling current naturally establishes the DC operating point without requiring impractically large resistance values, making the circuit implementable on silicon chips.
Solution Approach 2:
The tunneling current mechanism is self-regulating and automatically establishes the DC state without requiring external high-value resistors. The quantum tunneling effect inherently provides the bias definition function that would otherwise require large passive components.
3Ease of manufacture
If AC coupling circuits are implemented on silicon chips with available capacitor values (100 pF), then the chip can be manufactured, but the circuit cannot process low frequency signals below a certain threshold
Solution Approach 1:
The patent substitutes the AC coupling capacitor with a tunneling current-based coupling mechanism. This allows the circuit to maintain manufacturability with standard small-capacitor values on silicon chips while simultaneously enabling low-frequency signal processing capability that would otherwise require impractically large capacitors.
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 approach allows for efficient low noise amplification of small signals in low bandwidth applications on silicon chips by defining the DC state using quantum gate tunneling, reducing noise generation and enabling practical capacitor and resistor values, thus overcoming the limitations of prior art.
Implementation Method 1
gate oxide layers on the PMOS and NMOS transistors are of a thickness such that current is able to flow through the gate oxide from a channel beneath the gate oxide
Data Source
AI summary
An apparatus and method for using the known phenomena of quantum gate tunneling in semiconductor transistors to define the DC state of a charge-coupled amplifier is described. A first stage in which the tunneling current is bipolar (by pairing PMOS and NMOS transistors) in combination with a second stage with a controlled common mode voltage that can be used to control the first stage tunneling current, and thus the common mode voltage at the input. This can be done without the use of additional elements that may degrade performance or power consumption, since the input devices both process the input signal and maintain the DC operating point of the circuit. The approach may be advantageously used not only in charge-coupled amplifiers as described herein, but also in other capacitively coupled circuits such as charge balancing analog to digital converters (ADCs) and digital to analog converters (DACs).