Tektronix TPR1000, Руководство пользователя, Страница: 13 / 51

Preface
Why use a power-rail probe?
The added functionality, higher density, and faster switching speeds of modern electronic products drive the need for lower
supply voltages. Designers need to zoom-in on power rails to look for high-frequency intruder signals, measure ripple and
analyze coupling effects with tighter tolerances. Oscilloscopes often do not have enough offset to shift the noise and ripple
on DC rails to the center of the screen to make the needed measurements.
The TPR1000 and TPR4000 probes provide a low-noise measurement solution (oscilloscope and probe), which is critical to
not confuse the noise of the oscilloscope and probe with the noise and ripple of the DC supply being measured. The higher
input impedance in the probes minimize the oscilloscope loading effect on DC rails (50 k
Ω at DC). The probes provide higher
bandwidth to see more signal content (harmonics, faster ripples, etc.) on DC rails that could affect data signals, clocks, etc.
The TPR1000 and TPR4000 provide a best-in-class solution for power integrity and validation engineers in the high speed
(
μ P), low power (mobile) and switched-mode power supply markets. The probes are designed to offer the lowest noise
with high bandwidth at 60 V offset, fl exible connectivity options to cover customers challenges, and software packages to
cover the digital power management market.
Theory of operation
The block diagram shows the major circuit blocks or modules in the TPR1000 and TPR4000 probes.
Figure i: TPR1000 and TPR4000 clock diagram
The TPR1000 and TPR4000 function by extending the oscilloscopes offset capability while maintaining a low noise signal
path into the instrument. The linear dynamic range can be moved around the offset voltage operating window using the
DC offset control into the LF ampli
fi er. The LF ampli fi er can be disconnected when DC offset is not needed by setting the
coupling mode to DC reject in the instrument vertical menu. The bypass capacitor acts as a low impedance path for high
frequency components while blocking low frequency components. Because the TPR1000 and TPR4000 are designed for
measuring the low source impedances of power distribution planes it is not recommended to measure devices with source
impedances >1
Ω as it may cause distortion of the waveform.
TPR1000 and TPR4000 User Manual vii