Picotest VRTS3 Distributed System Demo Board

What makes the VRTS3 an essential tool for mastering power supply rejection ratio (PSRR) measurements?

The VRTS3 provides comprehensive infrastructure for learning PSRR measurements, quantifying how effectively regulators reject input noise. The board's multiple regulator topologies (switching regulator, linear regulator, voltage reference) allow engineers to compare PSRR performance across architectures. Engineers inject modulation signals using the J2111B Current Injector or J2110A Solid State Injector, measuring input and output to calculate PSRR across frequency. The REF03 voltage reference section is particularly valuable since references lack accessible feedback loops. Engineers observe PSRR degradation at higher frequencies and develop proficiency avoiding common measurement errors.

How does the VRTS3 parallel capacitor and plane section aid in understanding power distribution network resonance?

The VRTS3 features parallel tantalum and ceramic capacitors on a PCB plane demonstrating parallel capacitor resonance and PDN impedance characteristics. When capacitors with different values are paralleled, their equivalent series inductances and resistances interact, creating resonances that dramatically increase PDN impedance at specific frequencies. Using 1-port measurements with the P2104A Probe and vector network analyser, engineers directly measure impedance profiles and observe resonant peaks. This practical experience reveals how ESR damps resonances, how ESL determines resonant frequency, and why proper capacitor selection is critical. Plane impedance measurements demonstrate transmission line behaviour with resonances.

What clock circuit measurements can be performed on the VRTS3 and why are they important for power integrity?

The VRTS3 includes 10MHz and 125MHz clock circuits enabling exploration of the critical relationship between power supply noise and clock jitter. Clock jitter—timing variation in signal edges—directly impacts high-speed digital circuits, SerDes interfaces, and ADC performance. Engineers measure clock jitter, rise time, and jitter sensitivity using oscilloscopes or spectrum analysers. Injecting broadband noise into clock power rails with a J2150A Harmonic Comb Injector and 1-Port Probe demonstrates power supply rejection and PDN impedance resonance coupling. The dual-frequency implementation allows comparison across frequency ranges, teaching why flat, low PDN impedance is essential.

How can the VRTS3 microstrip section help engineers understand PCB transmission line effects?

The VRTS3 features 50Ω microstrips with intentional impedance aberrations, including one with a ground void—a common PCB defect affecting signal integrity. Using TDR techniques with the P2105A TDR Probe, engineers measure velocity factor, dielectric constant, characteristic impedance, and locate discontinuities. The broken ground plane demonstrates how discontinuities create impedance mismatches, reflections, and EMI issues. Engineers develop intuition for identifying transmission line problems by measuring propagation delay, rise time degradation, and reflection coefficients. This practical experience is invaluable for understanding how PCB layout affects power integrity, particularly plane resonances.

What educational advantages does the VRTS3 provide compared to expensive dedicated power integrity test systems?

The VRTS3 delivers comprehensive training at a fraction of the cost of high-end power integrity systems from Keysight, Rohde & Schwarz, or Ansys that cost tens or hundreds of thousands of pounds. Available from Debug Store, it enables engineers to learn power integrity concepts using existing vector network analysers and oscilloscopes. The eight circuit sections represent real-world distributed system components, enabling mastery of Bode analysis, NISM, PSRR testing, and impedance characterisation on one USB-powered platform. Extensively referenced in Picotest training materials, the VRTS3 accelerates competency development and provides exceptional return on investment.

How does the VRTS3 calibration section improve measurement accuracy and what standards does it support?

The VRTS3 includes dedicated calibration ports enabling precise Short-Open-Load (SOL) calibration before testing. The calibration section features precision test points for short, open, and 50Ω load calibration, plus a 1Ω verification resistor confirming calibration quality. This is essential for accurate milliohm-level impedance measurements in power distribution networks. After performing three-step SOL calibration, engineers should measure the 1Ω resistor to validate setup accuracy. The VRTS3 supports both 1-port and 2-port shunt-through measurements, achieving impedance measurements down to 100 milliohms (1-port) or 25 microohms (2-port). This calibration infrastructure teaches proper measurement practices translating directly to real-world applications.

What PDN probes work with the VRTS3 and how do they compare to traditional oscilloscope probes?

The VRTS3 works with specialised transmission line PDN probes offering significant advantages over traditional passive probes. The P2102A 2-Port Probe and P2104A 1-Port Probe maintain constant 50Ω impedance across their frequency range, with the P2104A supporting >6GHz bandwidth. Their remarkably low input capacitance (<1pF, typically 420fF) minimises loading compared to traditional probes. The "browser" design enables quick point-to-point measurements without soldering. Both probes include interchangeable heads and multiple attenuations, integrating seamlessly with vector network analysers and oscilloscopes.

Which Picotest signal injectors are compatible with the VRTS3 and what are their applications?

The VRTS3 supports multiple signal injectors optimised for specific measurements. For Bode plot analysis, the J2100A Injection Transformer (1Hz-5MHz) suits PFC regulators, whilst the J2101A (10Hz-45MHz) handles state-of-the-art switching regulators. The J2111B Current Injector provides DC-40MHz bandwidth for output impedance, PSRR, and NISM measurements. The J2110A Solid State Injector delivers DC to over 100MHz performance with exceptional linearity. All injectors feature 5Ω termination ensuring minimal loop impact.

How does the VRTS3 enable non-invasive stability measurement (NISM) and why is this important?

The VRTS3 facilitates non-invasive stability measurement (NISM), allowing engineers to assess voltage regulator stability without breaking the feedback loop. NISM derives phase margin from output impedance measurements using Picotest current injectors like the J2111B with vector network analysers. This technique is invaluable for fixed voltage regulators and integrated point-of-load converters where feedback loops are inaccessible. Unlike traditional Bode measurements requiring loop interruption, NISM works on fully operational circuits. The VRTS3's multiple circuit sections provide essential training for real-world applications where non-invasive assessment is the only feasible option.

What is the Picotest VRTS3 Distributed System Demo Board and what measurements does it support?

The Picotest VRTS3 Distributed System Demo Board is a USB-powered training platform containing eight circuit sections for comprehensive power integrity measurements. It includes a 2.8MHz switching regulator, 2.5V voltage reference, operational amplifier buffer, LD1086 linear regulator, 10MHz and 125MHz clock circuits, calibration ports (Short-Open-Load and 1Ω), parallel capacitors on PCB plane, and 50Ω microstrips with intentional aberrations. The board supports over 20 measurement types including impedance analysis, Bode plots, non-invasive stability measurement (NISM), PSRR testing, jitter analysis, TDR measurements, and EMI evaluation. This comprehensive platform enables engineers to master power integrity techniques using standard test equipment.