On-Chip RC Calibration Using Supply Bypass Capacitance
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Solution Overview
Problem
On-chip resistor and capacitor values in integrated circuits vary due to manufacturing processes, requiring precise calibration to ensure accurate performance in applications like cell phone transceivers, but existing methods rely on external precision components and pins, which are costly and inconvenient.
Innovation Solution
An on-chip RC calibration system that utilizes a supply bypass capacitor and a crystal oscillator to perform measurements without external precision resistors, using a switch to couple the capacitor to an RC oscillator, allowing for the determination of resistance and capacitance values using on-board components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If off-chip reference elements and dedicated pins are used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the calibration function with existing on-chip components (supply bypass capacitor, crystal oscillator, RC oscillator circuit) that are already present in the device. By combining these existing elements into a calibration system, the patent eliminates the need for separate off-chip reference elements and dedicated calibration pins, thereby reducing device complexity while maintaining calibration functionality
Solution Approach 2:
The supply bypass capacitor and crystal oscillator serve dual purposes: they perform their original functions (power supply filtering and frequency reference) while simultaneously being utilized for RC calibration measurements. This multi-functionality allows the same components to serve multiple roles, eliminating the need for dedicated calibration hardware
2Measurement precision
If off-chip reference elements are used for calibration, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The calibration functionality is merged with existing on-chip components that are already manufactured as part of the standard device fabrication process. By utilizing components that are already present on the chip (supply bypass capacitor, crystal oscillator, RC oscillator circuit), the patent eliminates the need for additional off-chip reference elements, thereby reducing manufacturing cost while maintaining calibration accuracy
Solution Approach 2:
The device performs its own calibration using its own internal components without requiring external reference elements. The supply bypass capacitor and crystal oscillator, which are already part of the device's internal architecture, are used to calibrate the RC oscillator circuit, making the calibration process self-contained and eliminating the need for expensive external calibration hardware
3Device complexity
If on-chip calibration circuits are used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent uses the supply bypass capacitor and crystal oscillator as intermediary elements to transfer the calibration function from external hardware to internal components. These intermediaries enable the calibration process to occur entirely on-chip by providing a reference frequency (from the crystal oscillator) and a known capacitance value (from the supply bypass capacitor) that can be used to calculate RC time constants without requiring external reference elements
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
Enables precise calibration of on-chip resistance and capacitance values without external components, reducing costs and pin usage, and ensuring consistent performance across different manufacturing variations.
Implementation Method 1
a supply bypass capacitor CK already available on the chip 110
Implementation Method 2
a crystal oscillator 130 (e.g., a reference oscillator)
Data Source
AI summary
A technique for calibration of on-chip resistance (R) and capacitance (C) values using an on-board bypass capacitor may include configuring an on-chip switch to selectively couple an on-chip calibration circuit to an on-chip port. The on-chip calibration circuit may include an RC oscillator having an RC time constant (RCTC). The on-board bypass capacitor may be coupled to the on-chip calibration circuit, by using the on-chip port. The on-chip R and C values may be calibrated using the on-chip calibration circuit and the on-board bypass capacitor.