Tektronix CT1, CT2, CT6 User Manual

AC Current Probes

CT1 • CT2 • CT6

Features & Benefits

High Bandwidth

Ultra-low Inductance

Very Small Form Factor

Characterize Current Waveforms up to <200 pSec Rise Times

Very Low Loading of Circuit Under Test

Fits Into Dense, Closely-spaced Circuit Designs

Applications

Data Storage Read Channel Design

Silicon Characterization

High-frequency Analog Design

ESD Testing

Signal Injection

Differential Current Measurements

Single Shot Low Rep-rate Pulse Measurements

Propagation Delay Measurement

CT6. Current Probe.

CT6 Current Probe

The CT6 is the newest addition to the

Tektronix portfolio of high-frequency

current probes. It is designed to meet

the needs of high-speed circuit design

and test applications which require ultra

high bandwidth, low inductance and

extremely small form factor. The CT6

provides up to 2 GHz bandwidth when

used with high-bandwidth oscilloscopes

such as the Tektronix TDS694C, TDS794D

and TDS7000 series oscilloscopes or

with other compatible 50 Ω input

measuring instruments. Low inductance

(<3 nH) assures that the loading effect of

the CT6 on the circuit-under-test will be

negligible, which is especially important

for today’s low-amplitude, high-speed

circuit designs such as disk drive read/

write preamplifiers. The probe is a

closed-circuit design which will accept

uninsulated wire sized up to 20 gauge.

This product is exempt from CE mark by

virtue of its 30 V voltage limit.

AC Current Probes

CT1 • CT2 • CT6

CT1/CT2. Current Probes with P6041 BNC Probe Cable.

CT1/CT2 Current Probes

The CT1 and CT2 Current Probes are

designed for permanent or semi-perma-

nent in-circuit installation. Each probe

consists of a current transformer and an

interconnecting cable. The current trans-

formers have a small hole through which

a current carrying conductor is passed

during circuit assembly.

The P6041 Probe Cable provides the

connection between the CT1 and CT2

Current Transformers and a BNC oscillo-

scope input. A 50 Ω termination is

required to terminate the cable when

connected to a high impedance (1 MΩ)

oscilloscope input. One probe cable can

be used to monitor several current trans-

formers that have been wired into a

circuit.

Miniature Construction

The CT1 and CT2 detachable cable

design enables one or more probes to be

located on circuit boards or in other

limited space areas.

The CT6 offers the smallest form factor

available, for measurement on ever-

shrinking circuit boards and components.

It is designed for temporary installation

and does not incorporate removable

cables, as the CT1 and CT2 do.

Extendible Probe Length

Specified rise time and bandwidth are

obtained when using the probe cables

provided: The P6041 cable use with the

CT1 and CT2 is 42 inches nominal. If

additional length is required, the cables

can be extended by using high quality

50 Ω cable and suitable interface connec-

tors. (Also see Special Probe Cables,

Optional Accessories.) Long cables may

degrade high frequency response.

High Sensitivity

The CT1 and CT6 provide an output of

5 mV for each milliamp of input current

when terminated in 50 Ω. The CT2

provides 1 mV per milliamp when termi-

nated in 50 Ω.

Typical Systems

The CT1, CT2 and CT6 high frequency

current transformers are dynamic (i.e.,

non-DC) current measuring devices. They

are typically used in conjunction with

compatible high bandwidth oscilloscopes

and other instruments to observe and/or

record high frequency current waveforms.

The CT1, CT2 and CT6 normally operate

directly into 50 Ω scopes and other

measuring device inputs.

The CT1 or CT2 can be used with 1 MΩ

input systems; use the P6041 probe

cable and terminate the output with a

50 Ω feed-through termination (see

Optional Accessories).

In all cases, the CT1, CT2 and CT6 must

work into 50 Ωs to obtain specified

performance and sensitivity.

Typical Measurement Applications

Differential Current Measurements

Most true-differential voltage amplifiers

have a maximum bandwidth of about

100 MHz. The CT1 or CT6 can make

differential current measurements to

1 GHz and 2 GHz, respectively, by

passing two wires carrying opposing

currents through the same core. The

displayed result is the difference current.

The CT2 can perform the same function

to 200 MHz.

In all cases, Derating with Frequency and

Amp-second Product (Current-time

Product) guidelines should not be

exceeded. (See Characteristics.)

Single-shot and Low Rep-rate Pulse Measurements

These common measurements are easy

to make with the CT1, CT2 or CT6

provided that your signal fits within the

Max Pulse Current and Amp-second

Product (Current-time Product) guidelines

for the specific current probe characteris-

tics.

For example, the CT2 is rated at

36 Amps peak, with an Amp-Second

-6

Product of 50 x 10

Seconds (50 Amp-

microseconds), therefore the CT2 can

safely handle a 36 Amp peak pulse with a

maximum width of 1.39 microseconds or

lower amplitude pulses for longer pulse

widths. The CT1, CT2 and CT6 all have

low frequency rolloff characteristics. Low

frequency “droop” will exhibit itself when

the pulse width approaches the L/R time

constant of the specific transformer.

Propagation Delay Measurements

Two CT1 or CT2 Current Transformers

with matching probe cables can be used

to measure propagation delay (transit

time) between the input and output

currents of high frequency devices. The

probe outputs are connected to the

inputs of dual channel real-time or

sampling scopes.

Verification of any Probe/Cable/Scope

System mismatch can be obtained by

passing the same signal current through

both probes and observing total system

delay difference, if any.

Current Probes • www.tektronix.com/accessories

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