CMOS Ring Oscillator Inverter Cell With Resistor Flicker Noise Attenuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inverter-based CMOS ring oscillators face significant noise issues, particularly flicker noise, as device dimensions shrink, which affects their performance in frequencies above 10 MHz, manifesting as phase noise or jitter in output signals.
Innovation Solution
Incorporating resistors into each inverter cell connected in cascade fashion, with their output feeding into the input of another cell, to attenuate flicker noise through resistor degeneration, while maintaining similar transconductance and power consumption performance as traditional designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If device dimensions are shrunk to maintain reasonable power consumption, then power consumption is reduced, but device noise increases significantly
Solution Approach 1:
Resistors are introduced as intermediary elements in the inverter cell to attenuate flicker noise. The resistors act as mediators between the transistors and the output, filtering out the harmful flicker noise component while allowing the useful signal to pass through, thus resolving the contradiction between low power consumption and noise reduction.
Solution Approach 2:
The invention changes the electrical parameters of the inverter cell by adding resistive elements, which modifies the noise characteristics. By adjusting the resistor values, the flicker noise attenuation can be optimized while maintaining the desired oscillation frequency and power consumption levels, effectively resolving the noise-power consumption tradeoff.
2Use of energy by moving object
If device dimensions are shrunk, then power consumption is reduced, but flicker noise becomes dominant at higher frequencies
Solution Approach 1:
The resistors serve as intermediary filtering elements that specifically target flicker noise attenuation. By placing resistors in the signal path, the circuit selectively attenuates the low-frequency flicker noise component that would otherwise degrade signal quality, while maintaining the oscillation performance and power efficiency.
3Device complexity
If traditional inverter-based design is used, then circuit simplicity is maintained, but phase noise and jitter increase in output signal
Solution Approach 1:
The invention merges the resistor element with the traditional inverter cell structure, creating a hybrid configuration that combines the simplicity of CMOS inverters with the noise-attenuation properties of resistive circuits. This integration achieves phase noise reduction without requiring a complete redesign of the oscillator architecture.
Data Source
AI summary
Disclosed is an inverter cell design comprising first and second transistors and first and second resistors. In disclosed embodiments, the first resistor is connected to a source of the first transistor and the second resistor is connected to a source of the second transistor. The first and second resistors are configured for connection to respective first and second voltage potentials. The inverter cells may be configured in a ring oscillator. A crystal oscillator may comprise an inverter cell according to the present disclosure.