FuturePlus SystemsOct 15, 2026, 2:43:09 PM4 min read

FuturePlus® Announces Support for Previous Generation Keysight Logic Analyzers

DDR5 and LPDDR5 validation with U4154A and U4154B

FuturePlus® Systems is excited to announce support for DDR5 and LPDDR5/LPDDR5X command/address analysis using the previous generation Keysight U4154A and U4154B logic analyzer cards with our FS2670A, FS2675, FS2910 and FS2915 interposers. Although Keysight no longer sells these cards, FuturePlus® is extending their usefulness for today’s memory validation work. U4154A/B cards can be found in large company laboratories around the world and on the used equipment market, giving engineering teams an opportunity to put existing equipment back to work. FuturePlus® will support these configurations, helping customers select the appropriate card speed option, interposer connections and acquisition setup.

For customers who need a complete solution or additional analyzer capacity, FuturePlus® also resells U4154A/B cards after testing them and proving that they work with our solutions—and backs the cards it resells with a FuturePlus® warranty! These previous generation cards offer 136 channels per module and, with the -02G option, 2.5 Gb/s full-channel state acquisition or up to 4 Gb/s in 68-channel dual-sample mode. The U4154B supports three merged modules versus two for the U4154A. The U4164A adds quad-sample state acquisition, dual thresholds, clock hysteresis, timing de-skew, 10 GHz quarter-channel timing and greater memory depth. The chart below shows how much acquisition capability remains available in the previous generation cards. [1–3]

Card comparison

Technical characteristic	U4154A	U4154B	U4164A
Physical channels per module	136	136	136
State acquisition with -02G	2.5 Gb/s full 4 Gb/s dual sample¹	2.5 Gb/s full 4 Gb/s dual sample¹	2.5 Gb/s full 4 Gb/s dual sample¹
Maximum state clock with -02G	2.5 GHz	2.5 GHz	2.5 GHz
State clock options	1.4 or 2.5 GHz	1.4 or 2.5 GHz	350 MHz, 700 MHz, 1.4 or 2.5 GHz
Maximum merged module set	2 modules 272 channels	3 modules 408 channels	3 modules 408 channels
Maximum full-channel memory	200 M samples	200 M samples	400 M samples
Conventional timing rate	2.5 GHz full 5 GHz half	2.5 GHz full 5 GHz half	2.5 GHz full 5 GHz half 10 GHz quarter
Timing Zoom	12.5 GHz 256 K samples	12.5 GHz 256 K samples	12.5 GHz 256 K samples
Distinctive acquisition features	Single and dual sample state	Single and dual sample state	Quad sample state Dual thresholds Clock hysteresis Timing de-skew

¹ The 4 Gb/s figure is typical in 68-channel dual-sample mode; 2.5 Gb/s full-channel is specified. Performance depends on installed options and probing. [1–3]

The technology that makes it possible

The key to DDR5 RDIMM capture is our active interposer technology. The FS2670A and FS2675 use an RCD-based capture path to buffer command/address signals and present them to the logic analyzer with a single-data-rate capture clock. This removes the DDR capture burden at the analyzer interface, allowing the previous generation U4154A/B cards to receive the command/address information. The interposer clock divider keeps the analyzer clock within its operating range and extends the captured time span for a given memory depth. The analyzer therefore works at the rate presented by the interposer, rather than the RDIMM’s advertised DQ transfer rate. The FS2675 also adds automated interposer training and support for RCD05 and RCD06. FuturePlus® supports these interposers with the U4154A, U4154B and U4164A in the appropriate configurations. [4, 5]

LPDDR5 and LPDDR5X offer another opportunity to use previous generation analyzer cards. Our FS2910 LPCAMM2 and FS2915 SOCAMM2 interposers expose the command/address bus for protocol analysis. The CA bus remains double data rate, but with a WCK-to-CK ratio of 4:1 its transfer rate is only one quarter of the DQ transfer rate. At 8533 MT/s DQ, that means approximately 2133 MT/s CA and a 1067 MHz command clock—comfortably within the 2.5 Gb/s full-channel capability of the U4154A/B-02G and U4164A-02G. FuturePlus® supports both interposers with all three card families, using the appropriate probing, channel mapping and B4661A software configuration. This brings current memory command/address analysis within reach of equipment already in your lab or available through FuturePlus® as a tested, warrantied solution. [6, 7]

Figure 1 FS2675 active DDR5 RDIMM interposer with logic analyzer pod connections and USB control

Interposer operation with the three card families

Interposer	Memory interface	Interface received by the analyzer	U4154A/B Previous generation	U4164A
FS2670A	DDR5 RDIMM	Active RCD capture path SDR capture clock	Compatible²	Compatible²
FS2675	DDR5 RDIMM RCD05 and RCD06	Active RCD capture path SDR capture clock	Compatible²	Compatible²
FS2910	LPDDR5/X LPCAMM2	DDR CA ¼ DQ rate at 4:1	Compatible² -02G at 8533 MT/s DQ	Compatible² -02G at 8533 MT/s DQ
FS2915	LPDDR5/X SOCAMM2	DDR CA ¼ DQ rate at 4:1	Compatible² -02G at 8533 MT/s DQ	Compatible² -02G at 8533 MT/s DQ

² FuturePlus® supports these command/address capture configurations. Select the card speed option and acquisition setup for the actual analyzer-side rate. The LPDDR5/X quarter-rate relationship applies to WCK:CK = 4:1; evaluate 2:1 operation separately.

FuturePlus® interposers in target systems

Figure 2 FS2910 LPCAMM2 interposer installed in a target system for LPDDR5 and LPDDR5X command/address capture

Figure 3 FS2915 SOCAMM2 interposer installed in a target system with command/address probing connections

Protocol decode using the U4154A

Figure 4 LPDDR5/LPDDR5X protocol decode captured using the FS2910 interposer and a previous generation U4154A logic analyzer card. The display shows decoded commands, rank and bank information, addresses and a traffic overview, with a reported command clock of 930.8 MHz.