Bootstrap Ring Oscillator for Low-Voltage Speed and Linearity
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Solution Overview
Problem
Circuits operating under low-voltage conditions face challenges in maintaining operating speed and linearity due to reduced driving current and increased sensitivity to process, voltage, and temperature variations, which degrades performance and extends the sub-threshold region operation.
Innovation Solution
A ring oscillator design comprising (2N+1) inverting delay circuit cells connected in series, with each cell receiving a control voltage, forming a loop structure that utilizes bootstrap delay circuit cells with PMOS and NMOS transistors and capacitors to enhance voltage swing and maintain operation away from the sub-threshold region, ensuring high linearity and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the operating voltage is reduced to lower power consumption, then power consumption decreases, but the driving current of the transistor decreases causing operating speed to slow down
Solution Approach 1:
The patent applies dynamics by making the gate voltage dynamic through a bootstrapping mechanism. The gate voltage is boosted above the supply voltage during specific phases of operation, allowing the transistor to maintain high driving current and fast switching speed even when the supply voltage is reduced. This dynamic voltage adjustment resolves the contradiction by enabling low power consumption at reduced supply voltage while preserving high operating speed through temporary voltage enhancement.
Solution Approach 2:
The patent changes the voltage parameter dynamically by implementing a bootstrapping circuit that generates gate voltages higher than the supply voltage. This parameter change allows the transistor to operate in the saturation region more effectively, maintaining high driving current and fast switching speed at reduced supply voltages, thus resolving the contradiction between low power consumption and high operating speed.
2Use of energy by stationary object
If the operating voltage is reduced to lower power consumption, then power consumption decreases, but the circuit becomes more sensitive to process, voltage, and temperature variations
Solution Approach 1:
The bootstrapping mechanism dynamically adjusts the gate voltage to compensate for PVT variations. By boosting the gate voltage above the supply voltage, the circuit maintains adequate driving current and switching performance even under process, voltage, and temperature variations, reducing sensitivity and improving reliability while operating at low supply voltages.
Solution Approach 2:
The bootstrapping circuit provides beforehand cushioning by pre-charging the gate to a voltage higher than the supply voltage before the transistor needs to switch. This creates a voltage margin that compensates for upcoming PVT variations, ensuring stable operation and reducing sensitivity to process, voltage, and temperature changes while maintaining low power consumption.
3Use of energy by stationary object
If the operating voltage is reduced, then power consumption decreases, but the potential difference between gate and source decreases causing driving current to reduce
Solution Approach 1:
The patent applies dynamics by implementing a bootstrapping circuit that dynamically boosts the gate voltage above the supply voltage during critical switching phases. This dynamic voltage enhancement maintains a large gate-source potential difference, ensuring high driving current is available when needed, while the overall supply voltage remains low for reduced power consumption.
Solution Approach 2:
The patent changes the gate voltage parameter to be higher than the supply voltage through bootstrapping. This parameter change ensures that the gate-source potential difference remains sufficiently large to drive high current, resolving the contradiction between low power consumption (low supply voltage) and high driving current by decoupling the gate voltage from the supply voltage.
Data Source
AI summary
A ring oscillator includes (2N+1) inverting delay circuit cells, and each delay circuit cell has an input port and an output port, where N is an integer larger than zero. Each of these (2N+1) inverting delay circuit cells receives a control voltage, and all of the (2N+1) inverting delay circuit cells are electrically connected with each other in series. Furthermore, the input port of one of the (2N+1) inverting delay circuit cells is electrically connected with the output port of an adjacent delay circuit cell of the (2N+1) inverting delay circuit cells.