Ring Oscillator Current Mirror for Temperature-Stable Frequency
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Solution Overview
Problem
Newer CMOS technologies, such as 45 nm channel length, exhibit increased oscillation frequencies with temperature, requiring new circuit techniques for frequency stabilization in ring oscillators, as opposed to older technologies where frequencies decreased with temperature.
Innovation Solution
A ring oscillator circuit design incorporating a current mirror and a self-biased inverter, where the current mirror regulates the current through the inverters and the self-biased inverter diverts a portion of the current to counteract the temperature-induced frequency increase, using a current mirror circuit with NFET transistors and a self-biased inverter connected in a loop fashion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If newer CMOS technologies (45 nm and shorter) are used to reduce device size and improve integration, then manufacturing precision and productivity are improved, but oscillation frequency increases with temperature causing frequency instability
Solution Approach 1:
The ring oscillator is divided into two separate loops: a main oscillation loop and a compensation loop. The compensation loop contains a self-biased inverter that generates a compensating signal to counteract temperature-induced frequency changes in the main loop, thereby stabilizing the overall oscillation frequency while maintaining the benefits of newer CMOS technologies
Solution Approach 2:
A compensation mechanism is implemented where the self-biased inverter in the compensation loop detects temperature-induced frequency changes and generates a compensating signal that feeds back to counteract these changes. This feedback approach actively stabilizes the oscillation frequency against temperature variations in newer CMOS processes
2Stability of the object's composition
If temperature compensation circuits are added to stabilize frequency, then frequency stability is improved, but device complexity increases
Solution Approach 1:
The compensation function is merged into the existing ring oscillator structure by adding a second loop with a self-biased inverter that shares common elements with the main oscillation loop. This integration approach provides frequency stabilization while minimizing the increase in overall device complexity compared to separate compensation circuits
Data Source
AI summary
A ring oscillator circuit is disclosed. The ring oscillator in one embodiment includes an odd number of inverters connected in a loop fashion, a current mirror having a drain of a first transistor connected to the inverters, and a self-biased inverter connected to a drain of a second transistor of the current mirror.