New Industry Products

Power Rail Probes with Lowest System Noise

January 12, 2019 by Scott McMahan

Tektronix has introduced the TPR1000 and TPR4000 power rail probes that can be used to carefully measure and analyze power rails. The power rail probes combine with the 12-bit 5 or 6 Series MSO mixed signal oscilloscopes to deliver what the company claims to be the lowest system noise of any power-rail measurement solution available.

These probes are designed especially for power integrity/validation engineers working on high speed, low power or switched-mode power supply designs. The new probes come with a complete set of connectors for small, difficult-to-access test points, thereby helping to reduce connection frustration.

"As advanced embedded designs adopt faster clocks and high-speed serial buses, designers across many industries, including automotive, aerospace, medical, industrial, and consumer electronics need to ensure clean power to their processors, ASICs and FPGAs. Simultaneously, the push toward higher power efficiency is driving signal amplitudes lower. Power rail noise from switching (including harmonics), crosstalk, and other sources has become a more significant issue for many of us," observed Ahmed Eisawy, Product Marketing Manager, Probing Solutions at Tektronix in a blog posting.

Challenges of Accurate Power Rail Measurements: 

  • Noise from the oscilloscope and probe is indistinguishable from the noise and ripple of your dc supply
  • Oscilloscopes often don't have enough offset to shift dc rails onto the display
  • Low-impedance probes can load down a power rail - changing the way it performs. However, high-impedance, high-attenuation probes are usually noisy.
  • The perfect probe would present a high resistance to dc but 50 ohms for dc.
  • Probes may not have sufficient bandwidth to see GHz noise that can affect high-speed drivers

According to the company, the new TPR1000 and TPR4000 power rail probes address each of these issues. The ultra-low noise contribution of the probes helps designers measure the noise on their DUT - well below a millivolt. The probes provide up to 60V offset, 1V dynamic range and up to 4GHz of bandwidth. The probes' connection options cover most scenarios.

The company says that various solder-in tips provide reliable access to hard to reach, sensitive signals with optimal signal resolution at up to 4GHz. Also, SMA, MMCX, U.FL and square pins are included for connecting to test points. An optional handheld browser enables quick measurements up to 1GHz. Tektronix notes that its low-noise oscilloscopes coupled with the lowest additive noise from its new power rail probes offer a measurement solution to help engineers ensure clean, noise-free voltage sources in their designs.

Key performance specifications

  • Compatible with the 6 series MSO, 5 series MSO, MSO/DPO3000, MDO/DPO4000, MSO/DPO5000, DPO7000, and DPO70000 1oscilloscopes
  • Bandwidth: 2
    • dc coupling mode:
      • TPR1000: dc to 1GHz
      • TPR4000: dc to 4GHz
    • dc reject mode:
      • TPR1000: 10kHz to 1GHz
      • TPR4000: 10kHz to 4GHz
  • Dynamic range: Up to 60Vdc, 1Vp-p ac 3
  • Attenuation: 1.25x2
  • Measurement accuracy:
    • dc linearity: <0.1%
    • dc offset drift: ±100µV
    • Step response long-term aberrations: ±1%
  • Noise:
    • <300µVp-p noise on 6 Series MSO (20MHz BW Limit)
    • <1mVp-p noise on 6 Series MSO (Full Bandwidth)
  • Input impedance:
    • 50kΩ dc to 1 kHz
    • 50Ω dc > 100kHz
  • Temperature range at tip: 4
    • -40 to +85 °C (standard accessories)
    • -40 to +155 °C (high temperature cable option)
  • Offset:
    • ±60V offset range
    • Offset setting error: ±2 mV max, ±0.4µV typical

Available for order with shipments expected to start in late March 2019, the 1 GHz TPR1000 and 4 GHz TPR4000 single-ended power rail probes with the TPR4KIT accessory kit are $4,000 and $6,000 respectively.