The 1-port probe, being a unity gain wide bandwidth probe,
allows the measurement of ripple and noise with optimum signal to noise ratio
(SNR). The 2-port probe can be used to
transmit a load current step through one port, while measuring the response
from the other port, simultaneously. The
probes can both be used to inject noise for the assessment of sensitivity to
the power supply for sensitive circuits such as clocks and LNAs. The probes are
supported by a wide range of signal injectors and accessories, such as DC
blockers, preamplifiers, and high speed current injectors.
The high-bandwidth (DC-1.3GHz), variable-pitch probe tip
design enables accurate impedance measurements for high-speed PCB development
and manufacturing. It eliminates the need for soldering SMA cables to your
board and the risk of damaging fine copper pads or pulling up small components.
You can get connectivity to circuit boards and devices without connectors.
The probes are compatible with all equipment including VNAs,
oscilloscopes, and spectrum analyzers and come with an accessory kit (see above
photo) that includes a variety of probe tips and lead extenders, as well as, a
DC blocking device. The probes are also designed to work with the Picotest J2180A
low noise preamplifier to improve signal to noise performance and the J2102A
common mode transformer which eliminates the DC ground loop.
What’s a Transmission Line Probe
Transmission line probes are a special type of passive probe
that replaces the high impedance probe cable found in a traditional passive
probe with a precision transmission line, that has a characteristic impedance
that matches the oscilloscope’s input (50Ω). This greatly reduces the input
capacitance to a fraction of a picofarad, minimizing the loading of high
frequency signals. The probes are
referred to as ‘PDN’ probes, because of
their effective use in measuring the low and ultra impedances found in power
distribution networks.
The input impedance of the Picotest probes remains nearly
constant over their entire frequency range. A traditional ÷10 passive probe has
a high input impedance at DC, however, this impedance drops rapidly with
frequency, passing below the input impedance of a transmission line probe at
<100MHz. The probes are useful in applications that produce fast rising,
narrow pulses with amplitudes which exceed the dynamic range of active probes.
They also tend to have less parasitic effects on frequency response and so they
are ideal for measuring impedance. By
providing a simple yet elegant solution to probing high-frequency signals,
Picotest’s one and two port transmission line probes preserve signal fidelity
and allow high-bandwidth test equipment to properly measure circuit
characteristics.
Impedance Demands New Probe CapabilitiesHigh speed
applications put pressure on the measurement of power supply busses to
unprecedented frequencies. As an example, the measurement of power distribution
network (PDN) impedance for FPGAs generally requires the measurement of impedance
levels in the milliohm scale at frequencies exceeding 1GHz. Measuring the high
speed step load response in power systems using 2-port impedance is difficult
because of the need to connect two 50Ω transmission lines to the output
capacitor. Compounding this difficult
task is that these measurements often need to be made in very small circuits
such as cell phones, solid state disk drives, and computer tablets; to name
just a few examples.
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