Ring Oscillator PTAT Current Tracking for Temperature Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ring oscillators with temperature compensation have poor temperature compensation capability due to the PTAT current being related to the square of the CTAT resistance.
Innovation Solution
A temperature compensated oscillator is designed with a current source generating a PTAT current related to the first power of the resistance, and a ring oscillator with a CTAT oscillation frequency, utilizing a tracking MOS device and a resistor in series to achieve effective temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PTAT current is related to the square of the CTAT resistance, then the current generating circuit can provide temperature compensation, but the temperature compensation capability is poor
Solution Approach 1:
The patent changes the mathematical relationship between PTAT current and resistance from a square relationship to a linear relationship. By modifying the current generating circuit to produce PTAT current proportional to the first power of resistance rather than the square, the temperature compensation precision is significantly improved while maintaining the temperature compensation function.
2Stability of the object's composition
If a current generating circuit generates PTAT current to compensate CTAT delay, then the oscillation frequency can be stabilized, but the relationship between PTAT current and resistance squared limits compensation effectiveness
Solution Approach 1:
The patent modifies the parameter relationship in the current generating circuit by changing how PTAT current relates to resistance. Instead of PTAT current being proportional to resistance squared, the circuit is designed so that PTAT current is proportional to resistance to the first power, thereby enhancing temperature compensation capability and oscillation frequency stability.
Solution Approach 2:
The patent implements a feedback mechanism where the PTAT current generated by the current generating circuit is fed back to the ring oscillator to compensate for CTAT delay effects. By adjusting the PTAT current based on temperature variations, the system maintains stable oscillation frequency across different temperatures.
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 proposed solution significantly improves the temperature compensation capability by making the PTAT current proportional to the first power of the resistance, ensuring that the oscillation frequency remains stable across varying temperatures.
Implementation Method 1
the gate-source voltage of the tracking MOS device has the same CTAT coefficient as the gate-source voltage of the at least one first MOS device, so that when the temperature compensated oscillator operates, there is a tracking effect between the tracking MOS device and the at least one first MOS device, so as to compensate the CTAT oscillation frequency
Implementation Method 2
the resistor has a CTAT resistance, and the PTAT current is proportional to a compensation current flowing through the resistor
Implementation Method 3
a current source, configured to generate a proportional to absolute temperature (PTAT) current
Data Source
AI summary
A temperature compensated oscillator includes: a current source configured to generate a proportional to absolute temperature (PTAT) current; and a ring oscillator which has a complementary to absolute temperature (CTAT) oscillation frequency and is configured to receive the PTAT current to generate an oscillation signal. The current source includes a tracking MOS device and a resistor which are coupled in series. The tracking MOS device and at least one MOS device of the ring oscillator have the same conductive type, and a gate-source voltage of the tracking MOS device and a gate-source voltage of the at least one MOS device have the same CTAT coefficient, such that when the temperature compensated oscillator operates, the tracking MOS device and the at least one of the first MOS device have a tracking effect to compensate the CTAT oscillation frequency.