On-Chip Oscillator Frequency Measurement Using Self-Test Logic
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Solution Overview
Problem
The high cost and complexity of testing high-frequency oscillators in integrated circuit devices require expensive and sophisticated test equipment, limiting testing to serial processes and increasing production costs.
Innovation Solution
An integrated circuit device with an on-chip oscillator, featuring a phase locked loop (PLL) and test control logic circuit, allows for parallel testing by using two counters and a test control logic circuit to determine the oscillator's output frequency without expensive equipment, enabling simple and low-cost automated testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive high precision test equipment is used to test oscillator frequency, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The oscillator device performs self-testing by incorporating test control logic and counters internally. The test control logic receives a start signal, activates the counter to count oscillator cycles, and automatically calculates frequency, enabling the device to test itself without external sophisticated equipment.
Solution Approach 2:
A counter circuit is introduced as an intermediary element to measure oscillator frequency by counting cycles over a predetermined time period. This simple counting mechanism replaces complex measurement equipment while maintaining adequate measurement precision for production testing.
2Measurement precision
If serial testing is performed using expensive test equipment, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
Each oscillator device independently performs its own frequency measurement using internal test control logic and counters. This self-service capability enables parallel testing of multiple devices simultaneously, dramatically increasing productivity compared to serial testing where one device is tested at a time on expensive equipment.
3Measurement precision
If additional test board hardware with divider circuits is added for high frequency testing, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The complex divider circuits and frequency scaling hardware are extracted from the test board and replaced by a simple counter circuit that directly counts oscillator cycles. The counter's overflow mechanism naturally handles high frequency measurement without requiring external divider circuits, simplifying the overall test system.
4Productivity
If on-chip test circuitry is added to enable parallel testing, then productivity is improved, but device complexity increases
Solution Approach 1:
The test functionality is segmented into distinct modular components: test control logic for managing the test sequence, counters for frequency measurement, and interfaces for communication. This segmentation allows each component to be independently optimized and integrated, minimizing overall complexity while enabling parallel testing capability.
Data Source
AI summary
An integrated circuit device comprises internally on-chip an oscillator with a signal output. The device has a reference clock input, a first counter with a count input, a control input and a counter output, a second counter with a count input, a control input and an overflow indication output, and a test control logic circuit. The count input of the first counter is connected to the signal output of the oscillator. The count input of the second counter is connected to the reference clock input. The overflow indication output of the second counter is connected to an input of the test control logic circuit. The test control circuit has an output connected to the control input of the first counter to apply a stop counting control signal to the first counter after it has received an overflow indication signal from the second counter. The first counter after it has received a stop counting control signal provides a count at the counter output which is indicative of the output frequency of the oscillator. The device includes all the hardware necessary to perform an on-chip test of the oscillator, thereby obviating the need for serial testing on sophisticated and expensive test equipment.