Internal Signal Monitoring in Semiconductor Memory via Test Mode
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Solution Overview
Problem
Existing semiconductor memory devices face challenges in precisely monitoring internal signals without distortion, as conventional methods require skilled operation and can damage the device, and direct probing often distorts signals, making it difficult to monitor internal signals in packaged chips.
Innovation Solution
An internal signal monitoring device and method that utilize an internal signal input unit and output unit to transmit a monitor source signal to a predetermined pad in response to a test mode signal, allowing for precise monitoring without disturbing the internal signals, and can be integrated into semiconductor memory devices to monitor signals through external pins without unpackaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an oscilloscope connected to a Pico-probe or internal signal probing device is used to monitor internal signals, then the monitoring capability is improved, but the operation difficulty increases and the internal signals become distorted
Solution Approach 1:
The patent creates a copy of the internal signal through a monitoring circuit that generates a monitor source signal identical to the internal signal. This copy is then transmitted to an external pad for observation, allowing operators to view internal signals without directly probing them, thus eliminating the need for complex probe connection skills while maintaining monitoring capability
Solution Approach 2:
The patent introduces an intermediary monitoring circuit between the internal signal source and the external observation point. This intermediary circuit includes a buffer that copies the internal signal and transmits it to an external pad, serving as a mediator that allows observation without direct contact with the internal signal nodes, thereby avoiding signal distortion and reducing operation complexity
2Measurement precision
If a Pico-probe is directly contacted to a node to inspect internal signals, then the monitoring capability is improved, but the internal signals become distorted
Solution Approach 1:
Instead of directly probing the internal signal node which causes distortion, the patent creates an exact copy of the internal signal through a monitoring circuit. The monitor source signal is generated to be identical to the internal signal but is observed through an external pad, eliminating the harmful probing effect while maintaining measurement capability
Solution Approach 2:
The patent introduces a buffer circuit as an intermediary that receives the internal signal and generates a monitor source signal. This intermediary isolates the probing action from the internal signal node, allowing external observation without direct contact, thus preventing signal distortion caused by probe loading effects
3Measurement precision
If the protective coating is removed to monitor internal signals, then the monitoring capability is improved, but the device complexity and time consumption increase
Solution Approach 1:
The patent transitions the observation point from the internal dimension (requiring coating removal) to the external dimension by transmitting the monitor source signal to an external pad. This dimensional change allows signal monitoring through the existing protective coating, eliminating the need for coating removal processes while maintaining internal signal accessibility
4Measurement precision
If a packaged semiconductor chip is dismantled to monitor internal signals, then the monitoring capability is improved, but the productivity decreases
Solution Approach 1:
The patent enables observation of internal signals through external pads that remain accessible after packaging. By transmitting the monitor source signal to external pads, the system allows monitoring without dismantling the packaged chip, thus maintaining measurement capability while significantly improving productivity
Solution Approach 2:
The patent creates a monitor source signal that is a copy of the internal signal and transmits it to external pads. This copying approach allows the monitoring of internal signals in packaged chips through external access points, eliminating the need for chip dismantling and enabling rapid monitoring that improves productivity
Data Source
AI summary
An internal signal monitoring device in a semiconductor memory device includes: an internal signal input unit to receive an internal signal to be monitored and having an output to provide a monitor source signal in response to a test mode signal; and an internal signal output unit having an input coupled to the output of the internal signal input unit, the internal signal output unit to transmit the monitor source signal to a predetermined pad of the semiconductor memory device in response to the test mode signal.