CMOS Oscillator Circuit With Switched Capacitor Frequency Stabilization
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Solution Overview
Problem
Existing oscillator circuits face challenges in achieving a stable output frequency over an extended temperature range while minimizing power consumption and area consumption, and they often rely on external components that are expensive and have limited temperature stability.
Innovation Solution
A fully integrated CMOS oscillator circuit design utilizing a resistor-switched capacitor approach with a comparator and flip-flop circuit, where a capacitor is alternately connected to different supply terminals via resistors and controllable switches, allowing for temperature-stable frequency generation with low power consumption and low noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a quartz oscillator is used to achieve precise frequency stability, then the output frequency stability is improved, but the cost increases and the temperature range is limited
Solution Approach 1:
The patent extracts the frequency stabilization function from external quartz components and implements it internally using a CMOS oscillator circuit with temperature compensation. The temperature compensation mechanism is extracted from the external environment and integrated into the circuit itself, allowing the oscillator to maintain stability without requiring external quartz crystals.
Solution Approach 2:
The oscillator circuit is designed to perform multiple functions: frequency generation, temperature sensing, and temperature compensation all within a single integrated circuit. This multi-functionality eliminates the need for separate external components and allows the circuit to adapt to different temperature conditions while maintaining frequency stability.
2Ease of manufacture
If external components are avoided to reduce cost, then the manufacturing cost is reduced, but the temperature range and frequency stability are limited
Solution Approach 1:
The patent merges the oscillator, temperature sensor, and compensation circuitry into a single integrated CMOS circuit. This consolidation eliminates external components and reduces manufacturing cost while maintaining frequency stability through internal temperature compensation mechanisms that sense and compensate for temperature variations.
Solution Approach 2:
The circuit dynamically changes its operating parameters based on temperature conditions. By sensing temperature variations and adjusting compensation parameters internally, the oscillator maintains frequency stability across different temperature ranges without requiring external components, thus achieving both cost reduction and performance maintenance.
3Adaptability or versatility
If the temperature range is extended beyond standard limits, then the applicability is improved, but the frequency stability and power consumption become challenging
Solution Approach 1:
The oscillator circuit employs dynamic temperature compensation that continuously adapts to changing temperature conditions. The compensation mechanism actively adjusts circuit parameters in real-time based on sensed temperature variations, enabling the circuit to maintain frequency stability across an extended temperature range from -40°C to +170°C.
Solution Approach 2:
The circuit incorporates a feedback mechanism where temperature is sensed and used to adjust the oscillator parameters. This closed-loop control ensures that frequency stability is maintained across extended temperature ranges by continuously compensating for temperature-induced drift through internal feedback signals.
4Area of stationary object
If fully integrated CMOS oscillator is used to reduce area consumption, then the area is reduced, but achieving low power consumption and low jitter becomes more difficult
Solution Approach 1:
The oscillator circuit is segmented into functional blocks (oscillator core, temperature sensor, compensation circuitry) that are efficiently laid out to minimize area. This segmentation allows for optimized placement and routing, reducing overall area consumption while maintaining signal quality through controlled signal paths and minimized interference between blocks.
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 design achieves a stable output frequency with low power consumption and reduced area usage, maintaining performance across a wide temperature range without the need for external components, and allows for trimming of components to adjust the output frequency accurately.
Implementation Method 1
a capacitor being arranged in a current path between the at least first supply terminal and the at least second supply terminal and having a first side and a second side, wherein each of the first and second side of the capacitor is alternately connected to the at least one first and second supply terminal
Implementation Method 2
a comparator having a first input terminal to apply a first input signal, a second input terminal to apply a second input signal and an output terminal to generate a comparator output signal. The comparator is configured to generate the comparator output signal in dependence on the comparing of the first and second input signal
Data Source
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AI summary
An oscillator circuit (10) comprises a current path (100) including a capacitor (110) having a first side (S110a) and a second side (S110b), wherein each of the first and second side (S110a, S110b) of the capacitor (110) is selectively connectable to at least a first supply terminal (VD) to apply a first voltage potential (VDDA) or a second supply terminal (VS) to apply a second voltage potential (VSS). The oscillator circuit (10) comprises a comparator (200) having a first input terminal (I200a) being selectively connectable to the first or the second side (S110a, S110b) of the capacitor (110), and a second input terminal (I200b) being connected to a terminal (VR) to apply a reference voltage (VREF). An output signal (OUT, OUTB) of the oscillator circuit is generated in dependence on a comparator output signal (VCFF) of the comparator (200).