Oscillator Self-Calibration via Scribe Seal Conductors
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Solution Overview
Problem
Individually testing and calibrating each oscillator circuit assembly for temperature-induced frequency drift is time-consuming and expensive, as it requires post-packaging calibration, whereas existing methods lack efficient simultaneous calibration techniques for multiple oscillator circuit assemblies on a silicon wafer.
Innovation Solution
The implementation of an oscillator circuit assembly with built-in self-calibration circuitry, including a digital phase-locked loop, temperature sensor, and non-volatile memory, allows for simultaneous calibration by propagating power and reference frequency signals through conductors penetrating the scribe seals, enabling real-time adjustment and storage of tuning values to compensate for temperature-induced frequency drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual calibration is performed for each oscillator circuit assembly after packaging, then calibration accuracy is achieved, but calibration time and cost increase significantly
Solution Approach 1:
Multiple oscillator circuit assemblies are merged onto a single silicon wafer during fabrication, allowing simultaneous calibration of all assemblies through shared calibration circuits and conductors. This combining approach maintains individual calibration accuracy while reducing total calibration time by processing multiple units in parallel rather than sequentially.
Solution Approach 2:
The calibration system uses universal calibration circuits and reference frequency sources that can serve multiple oscillator assemblies simultaneously. The same calibration infrastructure performs calibration for all assemblies on the wafer, eliminating the need for separate calibration equipment for each individual assembly.
2Reliability
If traditional post-packaging calibration methods are used, then each assembly is individually calibrated, but the process becomes expensive and time-consuming
Solution Approach 1:
Calibration is performed at the wafer level before the assemblies are singulated and packaged individually. This preliminary calibration action allows all assemblies to be calibrated while still connected on the wafer, maintaining calibration reliability through proper measurement while significantly reducing manufacturing cost by avoiding repeated handling and separate calibration setups.
Solution Approach 2:
Each oscillator circuit assembly includes built-in calibration circuits that enable self-calibration or automated calibration without requiring external specialized equipment for each assembly. The assemblies essentially calibrate themselves through the shared wafer-level calibration infrastructure, reducing overall system cost and complexity.
3Productivity
If simultaneous calibration of multiple assemblies is attempted, then calibration efficiency improves, but signal propagation through scribe seals adds complexity
Solution Approach 1:
Conductors are introduced as intermediary elements that penetrate through the scribe seals to connect the calibration circuits with the oscillator assemblies. These intermediary conductors provide reliable signal paths through the otherwise isolated scribe seal regions, enabling simultaneous calibration while managing the routing complexity through systematic conductor design.
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
This method enables rapid and cost-effective simultaneous calibration of multiple oscillator circuit assemblies on a wafer, reducing calibration time and cost by allowing temperature change and calibration without soak time, thus effectively addressing the inefficiencies of traditional post-singulation calibration methods.
Implementation Method 1
The digital phase-locked loop circuit includes an output, a first input, and a second input. The output of the digital phase-locked loop circuit is coupled to the input of the oscillator circuit. The first input of the digital phase-locked loop circuit is coupled to the output of the oscillator circuit. The second input of the digital phase-locked loop circuit is coupled to the reference frequency terminal.
Implementation Method 2
The calibration circuit is coupled to the oscillator circuit, and includes a reference frequency terminal and a digital phase-locked loop. The conductor extends to an edge of the oscillator circuit assembly and penetrates the scribe seal.
Data Source
AI summary
An oscillator assembly includes a scribe seal, an oscillator circuit, and a calibration circuit. The oscillator circuit includes an output. The calibration circuit is coupled to the oscillator circuit. The calibration circuit includes a reference frequency terminal, a conductor coupled to the reference frequency terminal, and an oscillator input terminal. The conductor extends to an edge of the oscillator circuit assembly and penetrates the scribe seal. The oscillator input terminal is coupled to the output of the oscillator circuit.