Flash Memory Controller Encoder BIST Circuit Testing
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Solution Overview
Problem
In flash memory controllers, it is challenging to accurately and quickly determine if the encoding or decoding functions are faulty without causing unnecessary waste or requiring debonding of the flash memory chip during testing.
Innovation Solution
An encoder built-in self-test (BIST) circuit within the flash memory controller generates input data and encodes it to produce a check code, allowing for functional testing without accessing any flash memory, thereby isolating the encoder for independent testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flash memory controller is connected with the flash memory chip during testing, then the encoding and decoding functions can be tested, but the flash memory chip must be discarded or undergo debonding process if testing fails, causing waste and additional processing
Solution Approach 1:
The patent extracts the encoder from the flash memory system and creates a standalone self-test circuit that tests the encoder without requiring a flash memory chip. The control circuit generates test data and the encoder processes it to generate check codes, which are then verified without involving the flash memory chip, thus eliminating the risk of chip damage or waste from testing failures.
Solution Approach 2:
The flash memory controller performs self-testing of its encoder function through the built-in self-test circuit. The control circuit generates input data, the encoder encodes this data to produce check codes, and the system verifies the encoding function internally without external flash memory involvement, enabling the system to self-diagnose encoder faults without risking damage to connected components.
2Reliability
If the flash memory controller is connected with the flash memory chip during testing, then both encoder and decoder functions can be tested, but it is hard to accurately determine whether the problem is introduced by the encoder or the decoder
Solution Approach 1:
The patent segments the testing process into separate encoder-specific and decoder-specific tests. The built-in self-test circuit isolates the encoder testing from decoder testing by having the control circuit generate test data that passes through the encoder and is verified within the controller, allowing independent verification of encoder functionality without confounding decoder issues.
Solution Approach 2:
The control circuit acts as an intermediary that generates test data and receives encoded check codes from the encoder without involving the flash memory chip or decoder in the encoder testing process. This intermediary role allows the system to test the encoder in isolation, accurately determining whether faults originate from the encoder rather than the decoder or flash memory.
3Reliability
If the flash memory controller is connected with the flash memory chip during testing, then the encoding and decoding functions can be tested, but the testing process is time-consuming and requires additional debonding process
Solution Approach 1:
The patent implements preliminary encoder testing through the built-in self-test circuit before any flash memory operations are performed. The control circuit generates test data and the encoder processes it to create check codes that are verified within the controller, completing the encoder functionality test without requiring flash memory chip attachment, thereby eliminating the need for subsequent debonding processes and reducing overall testing time.
Data Source
AI summary
The present invention provides an encoder built-in self-test (BIST) circuit applied in a flash memory controller, wherein the encoder BIST circuit includes a control circuit and an encoder. In operations of the encoder BIST circuit, without accessing any flash memory, the control circuit generates input data to the encoder, and the encoder encodes the input data to generate a check code to the control circuit, wherein the check code is arranged to determine whether functions of the encoder fail or not.