AGILENT N4915A-005

Agilent N4915A-005
Serial Bus Switch
Data Sheet
Version 1.1
6.5 GBit/s 2 to 1 switch for high speed
differential signals
Low effect on signal integrity allows for usage
in physical layer test setups
Fast switching time (6ns typical)
Manual and triggered operation
Supported by Agilent N5990A test automation
No external power supply required
Power Supply
The N4915A-005 serial bus switch is designed for
high speed serial bus applications, such as for
example Serial-ATA and PCI Express. It can quickly
switch between one source and two sink devices or
one sink and two sources while having a minimal
effect on signal integrity.
The switch doesn’t require any power supply, it
operates solely on USB power via its back side mini
USB connector. It interfaces to any standard USB
host, as provided by many Agilent instruments or
by any standard PC. It doesn’t require any host software or driver installation.
Serial Bus Interface
The switch doesn’t have a dedicated power indicator. As soon as one of the switch position and one
of the trigger mode LEDs are illuminated the switch
is powered and in normal operation.
The switch is designed for switching a differential
signal as typically used in high speed serial bus
applications. Therefore the switch comes with two
channels that switch simultaneously.
Figure 1 illustrates a typical setup with two transmitters that are switched between one receiver.
Analogously two receivers can be switched between
one transmitting device.
Figure 1: Typical switch setup with two transmitters
For both channels the common connector (labeled
“C”) will be switched between connector “1” and
“2”. The switch position display will indicate the
current switch state by either illuminating a red
(connector 1) or a green (connector 2) LED.
Table 1: N4915A-005 electrical characteristics
6.5 GBit/s
Signal inputs/outputs
AC coupled
Max. signal amplitude per
1V @ 70 kHz to 12 GHz
2V @ 100 MHz to 12 GHz
Max. signal amplitude two
channels differential
2V @ 70 kHz to 12 GHz
4V @ 100 MHz to 12 GHz
Signal attenuation
1.5 dB (15%)
at 6 GBit/s
Transition times (20%-80%)
40 ps typical
when used
Switching time
6 ns typical
Total jitter (p-p)
20 ps typical
Skew between channels
2 ps typical
SMA, 3.5 mm
Power supply
100 nF at each
1) Total jitter was measured with J-BERT N4903A and 86100C DCA-J with
precision time-base using the following settings: BER 10-12, data rate 3
GBit/s, pattern 215-1 PRBS
Figure 2: N4915A-005 connector view
Max. usable data rate
Agilent N4915A-005 Serial Bus Switch Data Sheet Version 1.0
Usage in Test Automation and Serial-ATA
Receiver Compliance Test
Operation Modes
The switch is controlled by four buttons on the
front panel. Its current operation mode and switch
position are illustrated by front panel LEDs.
Both trigger modes make use of the trigger input.
The trigger mode buttons allow the user to switch
between a level static trigger mode and an edge trigger mode. In edge trigger mode the manual pre-set
buttons are also active. As an edge trigger toggles
between the two switch positions the pre-set function allows the switch to initialize at a desired state.
For a manual only operation the edge/man trigger
mode will be used and the trigger input will remain
Figure 3: N4915A-005 front view with status LEDs
Trigger Input
The trigger input is designed to be interoperable
with Agilent Bit Error Ratio Testers such as the
J-BERT N4903A as well as Agilent Pulse Pattern
Generators such as the 81134A. For usage with
J-BERT’s trigger output choose the edge trigger
mode. When connecting to the output of a Pulse
Pattern Generator the level static mode can be
Table 2: N4915A-005 trigger input electrical parameters
Trigger input max. levels
± 3V
Trigger threshold
10 mV
Max. trigger rate
10 MHz
Trigger input connector
SMA, 3.5 mm female
Because of its external trigger modes the switch can
be controlled by other test equipment. Test equipment with integrated sequencing capabilities, such
as the J-BERT N4903A can control the switch position as part of a pattern sequence. Furthermore,
setups with multiple channels, such as the 81134A
Pulse Pattern Generator or the ParBERT 81250
systems can dedicate a data channel to control the
Some test applications require the user to change
cables between tools, for example in Serial-ATA
receiver compliance testing, different tools are
needed for turning on the test mode and for performing the actual test. Without a serial bus switch
this requires a change of cables as part of the test
Changing cables is certainly undesired in test automation as it consumes additional time and labor.
In order to avoid connectivity errors and preserve
mechanically sensitive test fixtures, setup changes
should also be avoided.
Therefore in Serial-ATA the N5990A test automation software has capabilities to remotely control
two switch devices to avoid manual steps.
Besides test automation in Serial-ATA the switches
also overcome the device disconnect issue: After
the test mode is turned on on a Serial-ATA product,
it doesn’t necessarily allow the user to manually
change the connectors. Being disconnected causes
some devices to return to the out-of-band mode.
Such products can still be tested when using the
serial bus switch. Because of the fast switching time
Serial-ATA products won’t detect a signal loss while
being switched between test tools.
Ordering Information
6.5 GBit/s 2 to 1 serial bus switch
Agilent N4915A-005 Serial Bus Switch Data Sheet Version 1.0
Related Agilent Literature
Agilent N4915A-005 Serial Bus Switch
Application in SATA Receiver Test
Application Note
Agilent J-BERT N4903A
High-Performance Serial BERT with
Complete Jitter Tolerance Testing
Data Sheet
BERT Family Brochure
Agilent ParBERT 81250
Parallel Bit Error Ratio Tester
Product Overview
Agilent Pulse Pattern and
Data Generators
Agilent 81133A and 81134A
3.35 GHz Pulse Pattern Generators
Data Sheet
Agilent N5990A Test Automation
Software Platform
Data Sheet
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© Agilent Technologies, Inc. 2007
Printed in USA, October 30th 2007