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B4621B Bus Decoder for DDR2, DDR3, or DDR4 Debug and Validation

Data Sheets


Accelerate your time to insight using the B4621B bus decoder for DDR2, DDR3, or DDR4 debug and validation. The B4621B provides complete protocol decode of memory transactions using a Keysight Technologies, Inc. logic analyzer as the analysis execution engine. (Select your logic analyzer module depending on your system data rate.)

The B4621B protocol-decode software translates acquired signals into easily understood, colorized, bus transactions showing associated data bursts for double-edge data-rate captures up to 2.5 Gb/s.

Valid read and write commands are decoded to include row and column addresses and the complete data burst associated with the command. The B4621B bus decode software anticipates key system attribute inputs (burst length, CAS latency and CAS write latency, chip selects) from default DDR2, DDR3, or DDR4 probing configurations and/or DDR Setup Assistant tool to accelerate decode of DDR2, DDR3, or DDR4 bus signals.


After installing the logic analyzer software and the B4621B software and loading the default configuration for your DDR memory, the B4621B icon will show up in the Keysight logic analyzer overview window between the logic analyzer module and the listing.

The properties button on the B4621B icon allows the selection of memory variables. Typically, preferences are filled out for you in default configurations for specific DDR probes and by the DDR Setup Assistant software tool 1, which walks you through state mode setups. Keysight’s 4.0 GB/s U4154A logic analysis module is recommended for all DDR2, DDR3, and DDR4 configurations.

The B4621B bus decoder for DDR2, DDR3, or DDR4 debug and validation operates with the following Logic Analyzers from Keysight Technologies. Logic analyzer selection criteria includes: logic analyzer specifications and characteristics, maximum DDR technology data rate, and minimum data valid windows of the data eyes at the logic analyzer probe point.

Default configurations speed setup and are easily modified

For custom embedded DDR technology applications, refer to on-line help in the logic analyzer software application for details on the B4621B bus decoder label requirements. For new embedded application configurations, Keysight recommends loading one of the existing default configurations that most closely matches your application and modifying that configuration for your unique embedded system.


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