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146 L4400 User’s Guide
7 Microwave Switch/Attenuator Driver
Using Single Drive Switches and Attenuators
Some microwave switches require a single drive. With single drive devices the
channel numbering is not consecutive across all channels in a bank (refer to
the channel numbering description on page 143).
The L4445A can provide single drive devices with either pulsed or continuous
drive current. Settings and parameters for continuous drive mode are given in
the next section.
Continuous Drive Current
Driving non- latching devices requires a power supply capable of handling
sustained high current requirements. You may only use continuous drive
current with channel configured for single drive. Additionally, to prevent
power supply loading, care must be taken when operating more than one
continuous drive at a time. The actual drive may be configured as either TTL or
open- collector operation.
Using Continuous Drive
The diagram below illustrates the continuous drive signals for two channels
(switches) and the relationship of the drive parameters to the power supply
requirements.
As shown in the diagram, the drive signal is initially applied to channel 1.
Drive is applied to channel 2 only after a power supply recovery period has
elapsed T(Recovery). The power supply recovery time is set using the the
ROUTe:CHANnel:DRIVe:TIMe:RECovery command. This parameter may be set
individually for each channel or will default to 0.0 ms following either a
SYSTem:RMODule:RESet or ROUTe:RMODule:BANK:PRESet command.
If you are verifying the channel closure (see page 149), you may also
specify a T(Settle) parameter. This parameter ensures the switch has had
time to change state before the position indicator is evaluated. This
parameter may be set individually for each channel or will default to 0.0
ms following either a
SYSTem:RMODule:PRESet or
ROUTe:RMODule:BANK:PRESet command.
T(Setttle)
T(Recovery)
Drive Ch 1
Drive Ch2
Start Drive
Channel 1
Start Drive
Channel 2
Channel 1 Position
Indicators Evaluated