Crystal Oscillator Amplitude Regulator With Back-Bias Threshold Control
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Solution Overview
Problem
Existing amplitude regulators in oscillator circuits, particularly in Pierce oscillators, lack precise control over when to switch off to optimize power efficiency and phase noise, limiting their performance.
Innovation Solution
An amplitude regulator circuit utilizing PMOS and NMOS transistors with a back-bias circuit to adjust the threshold voltage of the second NMOS transistor, allowing precise control over when to turn off the amplitude regulation, thereby improving power efficiency and phase noise performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the amplitude regulator is switched off early to improve power efficiency, then power consumption is reduced, but the phase noise performance deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the threshold voltage of the second NMOS transistor through back-bias control. By varying the back-bias voltage applied to the back-gate terminal of the second NMOS transistor, the threshold voltage is modulated to achieve precise control over the switching point of the amplitude regulator. This enables optimization of both power consumption and phase noise performance by finding the optimal threshold voltage parameter that balances early switching-off (for power efficiency) with adequate signal amplitude (for phase noise performance)
2Use of energy by moving object
If the amplitude regulator switches off at a higher voltage threshold, then power efficiency improves, but the tuning precision and control accuracy deteriorate
Solution Approach 1:
The patent implements dynamics by making the threshold voltage of the second NMOS transistor dynamically adjustable through back-bias control. Instead of a fixed threshold voltage, the back-bias circuit allows real-time modulation of the threshold voltage parameter. This dynamic control mechanism enables precise adjustment of the switching point voltage threshold, achieving both high power efficiency (through higher thresholds) and high tuning precision (through fine-grained voltage control via back-bias adjustment)
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 enables sharper tuning of the amplitude regulation, reducing power consumption and phase noise by accurately controlling the amplitude regulator's switching point, enhancing the overall performance of oscillator circuits.
Implementation Method 1
a back-bias circuit portion arranged to vary a back-bias voltage at a back-gate terminal of the second NMOS transistor, thereby varying a threshold voltage of said second NMOS transistor
Implementation Method 2
crystal oscillator circuits, which use a piezoelectric crystal (e.g. a quartz crystal) as the filter
Data Source
AI summary
An amplitude regulator circuit portion is arranged to supply a current to an inverter in an oscillator circuit. The regulator monitors a voltage at the input terminal of the inverter and varies the current supplied to the inverter in response to the monitored voltage. The amplitude regulator comprises first, second, and third PMOS transistors, and first and second NMOS transistors and is arranged such that an input node is connected to the input terminal of the inverter, a respective gate terminal of each of the first and second NMOS transistors, and a respective drain terminal of the first NMOS and first PMOS transistors. The amplitude regulator also comprises a back-bias circuit portions arranged to vary a back-bias voltage at a back-gate terminal of the second NMOS transistor, to vary a threshold voltage, where the threshold voltage of the second NMOS transistor is lower than that of the first NMOS transistor.