Operating at a frequency range of 100 kHz to 43.5 GHz, the PN400 harnesses the power of two SM family spectrum analyzers to create Signal Hound’s Phase Noise and VCO Test System. Enabling cross-correlation unlocks phase noise floors 20-30 dB lower than the capabilities of a single SM200 / SM435. The integrated low noise variable power supply and tune voltage facilitate precise VCO testing and characterization that includes tuning sensitivity and VCO pushing. Achieve high-performance automated test results in diverse systems with the PN400.
In this episode Shahriar presents a $50 eBay purchase which turns into a complete teardown and characterization of an Anritsu lithium niobate driver module. This 8 Vpp, 40 GHz amplifier is designed for high-speed optical modulators, and it still delivers impressive performance despite its age.
The video covers lithium niobate modulators, Mach-Zehnder operation, Vpi, bandwidth, voltage swing, and the trade-offs that shape optical driver design. The module is then tested with a Keysight Streamline vector network analyzer, including calibrated S-parameter measurements and gain compression from 1 GHz to 40 GHz.
A loose connector causes unstable bias current, but a careful reflow repair brings the amplifier back to its rated power consumption. The repaired unit measures approximately 27 dB of gain, about 40 GHz of bandwidth, and output power close to 8 Vpp at 1 dB compression.
The teardown reveals two gallium arsenide distributed amplifiers, broadband bias networks, output detector circuitry, wire-bonded interconnects, and the construction techniques used inside this high-speed module. High-magnification imaging also identifies the likely Triquint and Avago/Broadcom amplifier dies, along with their circuit topologies and related datasheets.
The final tests capture 8, 16, and 32 Gbit/s NRZ eye diagrams, followed by 32 Gbit/s PAM4 measurements. The results show the amplifier's output swing, bandwidth limits, nonlinear behavior, and the improvement available through input predistortion.
The video is organized as follows:
0:00 Introduction and eBay find
1:11 Lithium niobate modulator basics
5:04 Driver design trade-offs
6:55 Datasheet specifications
9:32 Bias board operation
11:05 VNA measurement setup
13:06 RF cables and calibration
15:39 Power safety checks
17:07 Streamline sweep configuration
21:14 VNA calibration
23:55 Repairing the loose connector
26:47 Small-signal measurements
28:39 Gain compression results
30:04 Detector output measurement
33:08 Module teardown
37:13 High-magnification die inspection
43:25 Finding the amplifier datasheets
46:09 Eye diagram test setup
51:41 8 Gbit/s eye diagram
52:48 16 Gbit/s eye diagram
53:38 32 Gbit/s eye diagram
55:29 PAM4 and predistortion
58:21 Final results and support
The Signal Path (TSP) is a science & electrical engineering video blog for industry professionals, researchers & students. TSP is a not-for-profit website dedicated to provide free education spanning a wide range of electrical engineering & science topics. Equipment reviews, tutorials and repair videos are posted regularly.
