The Agilent/Keysight N4876A is a 2:1 multiplexer that doubles the pattern generator data rate in BERT systems, enabling accurate characterization of high-speed serial interfaces up to 28.4 Gb/s. This front-end component extends the capabilities of existing BERT platforms such as the J-BERT N4903B and ParBERT 81250A, delivering NRZ output with excellent signal integrity.
Technical Specifications
Data Rate & Output Performance
• Output data rate range: 1.25 Gb/s to 27.0 Gb/s (up to 28.4 Gb/s with J-BERT N4903B Option D14)
• Output format: NRZ
• Output amplitude: 0.05 Vpp to 1.800 Vpp, 5 mV resolution (single-ended operation)
• Output voltage window: -2.00 V to +3.00 V
• Output transition times: 10 ps typical (20%–80%), 15 ps typical (10%–90%)
• Differential skew: 0 ps typical
• Intrinsic jitter: < 1 ps rms typical (disabled jitter sources, N4903B internal clock and pattern)
• Crossing point: Adjustable 20% to 80%
Input Specifications
• Data input voltage: High-level 0 V nominal (max +0.4 V), low-level -0.8 V nominal (min -1.2 V), DC coupled
• Clock input voltage: 0.4 Vpp nominal, maximum 800 mV in ±8 V window, AC-coupled
• Input impedance: 50 Ω
• Input format: NRZ
Interfaces & Connectivity
• Output: Differential or single-ended, DC coupled, 50 Ω impedance; 2.4 mm female connector
• Input: Single-ended, 50 Ω impedance; SMA female connectors
• Remote control: USB 2.0, LAN (rear panel), SCPI programming
• Control integration: Via J-BERT N4903B (USB)
– Key Features
• Compact form factor enables placement close to device under test, minimizing measurement influence
• Low intrinsic jitter (< 1 ps rms) and fast transition times ensure precise signal characterization
• Variable Clk/2 jitter: 45% to 55% or ±10 ps (whichever is less)
• External termination voltage adjustable from -2.00 V to +3.00 V
• Transparent to timing jitter on clock input; SNR and ISI added post-multiplexer
– Typical Applications
High-speed serial interface validation in semiconductor, communications, storage, and computer industries. Suitable for characterizing serial interfaces requiring precise BERT measurements above single-BERT capabilities.
