Differential Oscillator Trimming with Back-Gate Comparator Tuning
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Solution Overview
Problem
Oscillators manufactured with varying material impurities require trimming to achieve a desired frequency, but existing trimming methods cause noise, power consumption issues, and glitches due to high sensitivity to parasitic capacitance and resistance.
Innovation Solution
A trimmable resistor and comparator-based solution with one-hot encoding and symmetrical structure reduces parasitic effects, allowing for low-power, glitch-free frequency adjustment using a trimmable resistor and back-gate voltage tuning of comparators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional trimming methods are used to adjust oscillator frequency, then frequency accuracy is improved, but noise and power consumption increase due to high sensitivity to parasitic capacitance and resistance
Solution Approach 1:
The patent introduces a buffer stage as an intermediary between the trimming mechanism and the oscillator core. This buffer isolates the sensitive oscillator circuit from the parasitic effects of the trimming components, allowing frequency adjustment without directly coupling the trimmer resistor to the oscillator nodes, thereby reducing noise and parasitic influence
Solution Approach 2:
The patent replaces traditional mechanical or direct electrical trimming methods with a voltage-controlled approach using a buffer stage. Instead of directly adjusting capacitor or resistor values connected to the oscillator, the system uses a voltage-controlled variable element (such as a varactor or FET-based trimmer) driven through a buffer, substituting direct mechanical/electrical adjustment with a voltage-controlled mechanism that has lower parasitic effects
2Measurement precision
If traditional trimming methods are used to adjust oscillator frequency, then frequency accuracy is improved, but power consumption increases due to high sensitivity to parasitic capacitance and resistance
Solution Approach 1:
The buffer stage acts as an intermediary that isolates the high-impedance oscillator circuit from the trimming mechanism. This allows the trimmer to operate at lower power levels since it doesn't need to drive the sensitive oscillator nodes directly, reducing overall power consumption while maintaining frequency accuracy
Solution Approach 2:
The voltage-controlled trimming mechanism replaces traditional high-power adjustment methods. By using a buffer stage to drive the variable element, the system achieves frequency control with lower power dissipation compared to direct trimming methods that require higher currents to overcome parasitic effects
3Adaptability or versatility
If traditional trimming methods are used to adjust oscillator frequency, then frequency tuning capability is improved, but glitches occur in the output signal due to high sensitivity to parasitic capacitance and resistance
Solution Approach 1:
The buffer stage serves as a mediator that decouples the trimming action from the oscillator output. When the trimmer adjusts frequency, the buffer isolates these changes from directly affecting the oscillator nodes, preventing glitches and signal instability while maintaining full frequency tuning capability
Solution Approach 2:
The voltage-controlled trimming approach replaces direct mechanical/electrical adjustment that causes glitches. The buffer stage ensures smooth transitions during frequency tuning by preventing direct coupling between the trimmer and oscillator, eliminating glitch generation while preserving adaptability
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 achieves low power consumption, reduced noise, and precise frequency tuning without glitches, with improved integral and differential non-linearity, and supports on-the-fly trimming.
Implementation Method 1
a comparator configured to produce the switching control by comparing a voltage of the capacitors at the inputs of the comparator to a preset threshold voltage
Implementation Method 2
a switch configured to connect the nodes alternatively to either a direct current power supply or a ground based on the switching control
Data Source
AI summary
According to an aspect, there is provided a swing-boosted differential oscillator (500) and a method for trimming the oscillator. The oscillator comprises a switch (110′) for connecting a set of capacitors (C1, C2) alternately to power supply and ground (102′, 112′) based on a switching control (116A′, 116B′), two comparators (502, 504) configured to produce an output signal of the oscillator (ck) and the switching control (116A′, 116B′) via a multiplexer (508) by comparing a voltage of the capacitors (C1, C2) at the inputs (VC1, VC2) of the comparators to a threshold voltage (VBB), where the comparators comprising back gate bias input (FIG. 5: 804, FIG. 8: Vbb, 804) for controlling the threshold voltage of the comparators, the threshold voltage trimming the frequency of the output signal of the oscillator.