Temperature-Compensated RC Oscillator for Stable Refresh Timing
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Solution Overview
Problem
Conventional oscillators in integrated circuits are temperature-dependent, leading to changes in oscillating signal periods, which can result in increased power consumption and undesirable timing of circuit operations, particularly affecting memory refresh operations across extreme temperature ranges.
Innovation Solution
The development of temperature-independent oscillator circuits using a pulse generator configuration that includes a capacitor, resistor, diode, and comparator, where the period of the oscillating signal is based on the RC time constant, with components having inverse temperature coefficients to cancel out temperature effects, ensuring a constant oscillating signal period across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RC oscillators are used in integrated circuits, then the oscillator can provide timing control for circuit operations, but the oscillating signal period changes with temperature, leading to increased power consumption and undesirable timing
Solution Approach 1:
The patent uses a current source with negative temperature coefficient to compensate for the positive temperature coefficient of the RC time constant. By changing the current parameter in opposition to temperature changes, the overall period remains stable across temperature variations, resolving the contradiction between timing accuracy and temperature independence.
2Device complexity
If conventional RC oscillators are used, then the circuit can operate with simple components, but the changing resistance and voltage characteristics with temperature result in period changes and increased power consumption
Solution Approach 1:
The patent introduces a current source parameter that changes with temperature to compensate for RC characteristic changes. This parameter change approach maintains period stability without requiring complex circuit reconfiguration, achieving power efficiency while preserving relatively simple circuit architecture.
3Reliability
If temperature-independent design is implemented using current sources with negative temperature coefficients, then the oscillating signal period remains stable across temperature ranges, but the circuit requires additional components beyond simple RC
Solution Approach 1:
The patent introduces a current source as an intermediary element that mediates between the temperature environment and the RC oscillator core. This intermediary component with negative temperature coefficient compensates for thermal effects without requiring complete redesign of the oscillator architecture, achieving period stability with moderate complexity increase.
4Ease of manufacture
If conventional oscillators are used without temperature compensation, then the circuit design remains simple, but refresh operations may occur at undesirable times and power consumption increases
Solution Approach 1:
The patent modifies the current parameter to have negative temperature dependence, which compensates for the temperature-induced changes in RC time constant. This parameter modification ensures that refresh operations occur at correct intervals across temperature ranges while maintaining relatively simple circuit implementation.
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 solution provides a stable oscillating signal period that is not affected by temperature changes, maintaining consistent refresh operations and reducing power consumption across a wide temperature range, thereby ensuring data validity in memory cells.
Implementation Method 1
a period of the periodic pulse signal is based at least in part on the RC time constant of the capacitor and the resistor
Implementation Method 2
the diode has a second temperature coefficient that is inversely related to the first temperature coefficient such that the period of the periodic pulse signal is relatively independent of changes in temperature
Implementation Method 3
The comparator may be coupled to the first and second nodes and configured to provide the periodic pulse based on voltages on the first and second nodes
Data Source
AI summary
Apparatuses and methods for temperature independent oscillator circuits are disclosed herein. An example apparatus may include a pulse generator circuit configured to provide a periodic pulse based on the charging and discharging and discharging of a capacitor and further based on a reference voltage. The pulse generator circuit may include a capacitor coupled between a first reference voltage and a first node, wherein the capacitor is configured to be charged and discharged through the node in response to the periodic pulse, a resistor and a diode coupled in series between a second node and a second reference voltage, and a comparator coupled to the first and second nodes and configured to provide the periodic pulse based on voltages on the first and second nodes, wherein a period of the periodic pulse is based at least on the resistor and the a current.