Relaxation Oscillator Using Switched-Capacitor Resistance for Stable Clocks
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Solution Overview
Problem
Conventional relaxation oscillators face a trade-off between power consumption and area usage due to the use of general resistors, which affects their performance and stability across varying manufacturing processes, source voltages, and temperatures.
Innovation Solution
The relaxation oscillator employs a transistor-based resistor and switched-capacitor resistor circuits to generate a reference voltage and threshold voltage, respectively, with a switch control circuit managing the charging and discharging of capacitors to produce a stable oscillating signal, independent of source voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If general resistors are used in relaxation oscillators, then the circuit implementation is simple, but power consumption increases and area usage increases
Solution Approach 1:
The patent transforms the resistor implementation from a passive component to an active transistor-based circuit. By changing the operating parameters and using switched-capacitor techniques, the equivalent resistance is generated dynamically, achieving both low power consumption and reduced area while maintaining the required functional complexity
Solution Approach 2:
The patent replaces physical resistor components with transistor-based active circuits. This substitution eliminates the need for large-area passive resistors and reduces static power consumption by using controlled current paths only when needed for oscillation operation
2Device complexity
If general resistors are used in relaxation oscillators, then the circuit implementation is simple, but area usage increases
Solution Approach 1:
The patent changes the physical implementation parameters by replacing extended resistor structures with compact transistor-based active circuits. The switched-capacitor technique generates equivalent resistance values without requiring large physical areas, thus reducing the overall oscillator footprint while maintaining implementation feasibility
Solution Approach 2:
The patent substitutes physical resistor components with transistor-based active circuits. This replacement dramatically reduces the area required since active transistor circuits occupy significantly less space than equivalent-value passive resistors, especially for the high resistance values needed in relaxation oscillators
3Ease of manufacture
If general resistors are used in relaxation oscillators, then the circuit is easy to manufacture, but performance stability across manufacturing processes deteriorates
Solution Approach 1:
The patent incorporates feedback mechanisms through the switched-capacitor circuit and transistor biasing networks. These feedback paths actively compensate for manufacturing variations and process deviations, stabilizing the oscillation frequency and performance across different manufacturing batches while maintaining ease of fabrication using standard CMOS processes
Solution Approach 2:
The patent uses active transistor circuits whose electrical characteristics can be dynamically adjusted through biasing and control signals. This allows compensation for manufacturing variations by tuning operating parameters, achieving stable performance across process variations without complicating the manufacturing process
4Device complexity
If general resistors are used in relaxation oscillators, then the circuit implementation is simple, but performance stability across source voltage changes deteriorates
Solution Approach 1:
The patent employs feedback through the switched-capacitor circuit and transistor biasing that actively regulates the oscillation parameters. This feedback mechanism compensates for source voltage fluctuations, maintaining stable oscillation frequency and waveform despite variations in supply voltage, while keeping the circuit implementation relatively simple
Solution Approach 2:
The patent uses dynamic switching and active control through transistors to adapt the circuit behavior to changing source voltage conditions. The switched-capacitor technique and transistor-based resistor dynamically adjust their characteristics in response to voltage changes, maintaining performance stability without requiring overly complex voltage regulation circuits
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 design reduces power consumption and area usage while maintaining stable performance across different conditions, providing a robust and efficient low-power clock signal generation.
Implementation Method 1
a reference voltage generating circuit configured to generate a reference voltage based on a transistor-based resistor
Implementation Method 2
a threshold voltage generating circuit configured to generate a threshold voltage using a switched-capacitor resistor circuit
Implementation Method 3
The switch control circuit may include a comparator configured to compare the variable voltage and the threshold voltage and determine a signal value of the control signal based on a result of the comparing
Data Source
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AI summary
A relaxation oscillator and a method of controlling the relaxation oscillator are disclosed. The relaxation oscillator includes a reference voltage generating circuit configured to generate a reference voltage based on a transistor-based resistor, a variable voltage generating circuit configured to generate a variable voltage based on the reference voltage and a control switch, a threshold voltage generating circuit configured to generate a threshold voltage using a switched-capacitor resistor circuit, and a switch control circuit configured to output a control signal to control the control switch based on the variable voltage and the threshold voltage.