HP 87204, 87206a, 252cb, 252cc schematic

Keysight 87204/87206A, B, C

Multiport Coaxial Switches

dc to 4 GHz, dc to 20 GHz, dc to 26.5 GHz

Technical Overview

High performance multiport
switches for microwave and RF
instrumentation and systems

– SP4T and SP6T conguration
– Exceptional repeatability for more than 5 million cycles
– Excellent isolation, typically >90 dB at 26.5 GHz
– Magnetic latching
– Terminated ports
– Self-interrupting drive circuit
– Fully compatible with Keysight 87130A/70611A switch drivers

2C

87204A,B,C

Modern automated test systems
demand higher accuracy and perfor­mance than ever before. The Keysight
Technologies Inc. 87204A/B/C and
87206A/B/C multiport switches
offer excellent insertion loss repeat­ability and high isolation necessary
to achieve superior test system
performance. Long life, repeatability,
and reliability reduce the cost of
ownership by reducing calibration
cycles and increasing test system
uptime. These features are vital to
ATS measurement system integrity
over time.

50 Ω Termination

6

RF Port

654321C

53

87206A,B,C

Description

The 87204A/B/C SP4T and
87206A/B/C SP6T terminated mul­tiport switches provide the life and
reliability required for automated test
and measurement, signal monitoring,
and routing applications. Innovative
design and careful process control
create switches which meet the
requirements for highly repeatable
switching elements in test instru­ments and switching interfaces. The
switches are designed to operate
for more than 10 million cycles. The
exceptional 0.03 dB insertion loss
repeatability is warranted for 5 million
cycles at 25 °C. This reduces sources
of random errors in the measurement
path and improves measurement
uncertainty. Switch life is a critical
consideration in production test
systems, satellite and antenna
monitoring systems, and test instru­mentation. The longevity of these
switches increases system uptime,
and lowers the cost of ownership
by reducing calibration cycles and
switch maintenance.

Figure 1. Keysight 87204A/B/C and 87206A/B/C simplified schematics

Operating to 4 GHz (A models),
20GHz (B models), and 26.5 GHz
(C models), these switches exhibit
exceptional isolation performance
required to maintain measurement

Option 100 provides solder terminal
connections in place of the 16-pin
ribbon drive cable. Option 100 does
not incorporate the “open all paths”

feature.
integrity. Isolation between ports
is typically >100 dB to 12 GHz and
>90 dB to 26.5 GHz. This reduces
the influence of signals from other
channels, sustains the integrity of the
measured signal, and reduces system
measurement uncertainties. These
switches also minimize measurement
uncertainty with low insertion loss
and reflection, which makes them
ideal elements in large, multi-tiered
switching systems.

Each port is individually controlled

by its corresponding “close” and

“open” control lines. All open paths

are terminated with 50-ohm loads.

A port is closed or open when its

corresponding “close” or “open” pin

is connected to ground. At this point,

the current to the solenoids is shut

off by the optoelectronic interrupts.

This improves reliability and extends

the life of the switch by eliminating

dc circuit contact failures characteris­Both the 87204A/B/C and
87206A/B/C are designed to fall
within most popular industry foot­prints. The 2¼ inch square flange
provides mounting holes, while the
rest of the 2½ inch long by 2¼ inch

tic of conventional electromechanical

switches. This configuration allows

compatibility with the Keysight

87130A and Keysight 70611A switch

drivers’ position monitoring and

reporting feature.
diameter body will easily fit into most
systems. Ribbon cable or optional
solder terminal connections accom­modate the need for secure and
efficient control cable attachment.

2

Applications

Multiport switches find use in a large
number of applications, increasing
system flexibility and simplifying
system design.

Simple signal routing

The simplest signal routing scheme
takes the form of single input to
multiple outputs. These matrixes are
often used at the input of an ana­lyzer to test several two-port devices
sequentially or to test multiport
devices. In surveillance applications,
a multiport switch can be used to
select the optimum antenna for
intercepting a signal.

Two methods can be used to accom­plish the single input to multiple out­put arrangement. Traditionally, where
isolation greater than 60 dB was
required, a tree matrix composed of
SPDT switches was used. While this
provided high isolation, it was at the
cost of more switches (Figure 2). The
87204 and 87206 switches have port­to-port isolations typically greater
than 90 dB at 26.5 GHz, eliminating
the need for a tree matrix to achieve
high isolation (Figure 3). In addition
to the reduced part count, the path
lengths are shorter, so insertion
loss is less. Also, paths are of equal
length, so phase shift is constant.

Figure 2. Tree matrix

Figure 3. Multiport matrix

Full access switching

Full access switching systems have

the flexibility to route multiple input

signals to multiple outputs simultane-

ously. Full access switching matrixes

are used in test systems to provide

flexible routing of signals between

different devices under test and

stimulus and analysis instrumenta-

tion. Cross-point matrixes, using

single-pole double-throw and cross-

point switches, have traditionally

been used to maintain high channel-

to-channel isolation (Figure 4). As

with the tree matrixes, this is at the

cost of hardware and performance.

Full access switching can also be

achieved using multiport switches

(Figure 5).

The advantage of the multiport matrix

over the cross-point matrix is lower

insertion loss and improved SWR

performance due to consistent path

length and fewer switches and con-

necting cables.

Figure 4. Cross-point matrix

3

Figure 5. Full access matrix

Dedicated switching

There are a number of applications
where switching will be used, not for
flexibility, but to accomplish a par­ticular function within an instrument.
For example, switched filter banks for
reducing harmonics in the output of
sources or at the input of analyzers
can use multiport switches in series
to select the right filter for the band
of interest.

Driving the switch

Each RF path is controlled indepen­dently. An “open” or “closed” signal
must be sent to achieve the desired
state for each section of the switch
(see Figure 8 on page 9 for drive con­nection diagrams).

– Connect pin 1 to supply (+20 Vdc

to +32 Vdc).

– Connect pin 15 to ground (see

Note 1).

– “Open” desired RF path by apply-

ing ground to the corresponding
“open” pin; for example, ground
pin 4 to open RF path 1 (see
Notes 2, 3).

– Close desired RF path by apply-

ing ground to the corresponding
RF path “close” pin; for example,
ground pin 3 to close RF path 1
(see Notes 2, 3).

– To open all RF paths, ensure

that RF path “close” pins are
disconnected from ground. Then,
connect pin 16 to ground. Note:
This feature is not available with
Option 100.

For larger switching systems, where
many switches will be used to
provide complex signal routing, a
switch driver such as the Keysight
87130A or 70611A is recommended.
The 87130A rack-and-stack switch
driver and the MMS-based 70611A
are convenient, flexible GPIB or MSIB
switch controllers, providing driver
circuitry, position monitoring, and
reporting, and firmware that makes it
easy to integrate switch components
into a switching system.

The 87130A must be controlled by

either a PC or workstation-based

GPIB controller and appropriate

software (for example, Keysight ITG

or VEE).

1

The 70611A gives manual control via

the MMS user interface or can also

be controlled via a GPIB-equipped PC

or workstation.

Accessory cables and adapters make

it easy to connect an 87204/87206

to the 87130A (see Ordering

Information). In addition, the built-in

firmware makes it possible to define

frequently used switch paths. With

the path command, macros can be

designed which open and close the

right solenoids to select the desired

switch port; this path may then be

named.

A programmable wake-up condition

makes it possible to ensure that the

matrix or switching system starts up

in a predetermined state.

For smaller switching needs, the

Keysight 11713B 10-channel attenua-

tor/switch controller provides simple

GPIB control for one 87206 and one

87204 or two 87204 switches with

Option 100. Connecting cables can be

ordered that make it easy to connect

the switches to the 11713B (see

Ordering Information).

Notes:

1. Pin 15 must always be connected to ground to enable the electronic position-indicating circuitry
and drive logic circuitry.

CAUTION: IF PIN 15 IS NOT CONNECTED TO POWER SUPPLY GROUND,
CATASTROPHIC FAILURE WILL OCCUR.

2. After the RF path is switched and latched, the drive current is automatically interrupted by the
electronic position-sensing circuitry. Pulsed control is not necessary, but if implemented, the
pulse width must be 15 ms minimum to ensure that the switch is fully latched.

3. Make-before-break switching can be accomplished by closing the new RF path before opening
the old RF path. This will simultaneously engage the old RF path and the new RF path. Once the
new RF path is engaged (15 ms), open the closed path by grounding the RF path open select
pin. Break-before-make is accomplished by opening the old RF path before closing the new
RFpath.

4

1. ITG: Instrument Test Generator, VEE: Visual
Engineering Environment