Rohde & Schwarz R&S FSP Series, Operating Manual

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Operating Manual 1164.4556.12 - 06 4.271
R&S FSP Instrument Functions
LO/IF ports for external mixers - Option R&S FSP-B21
The current is defined in the SELECT BAND table or set to the value of the Conver-
sion Loss table.
Fig. 4.36 Bias circuit of the R&S FSP
The voltage U
0
at the output of the operational amplifier can be set in the range –2.0
to +2.0 V An open-circuit voltage V
bias
of –0.5 to +0.5 V is obtained accordingly at
the output of the voltage divider. A short-circuit current of I
short
= V
0
/ 200
Ω
= -10
mA to + 10 mA is obtained for a short circuit at the output of the voltage divider. For
using biasing it is not important to know exactly the current flowing through the diode
since the conversion loss must be set to minimum with the frequency. It therefore
makes no difference whether the setting is performed by an open-circuit voltage or
by a short-circuit current.
A DC return path is ensured via the 66
Ω
resistor, which is an advantage in some
mixers.
4.13.3 Conversion Loss Tables
Conversion loss tables allow the conversion loss of the mixer to be taken into
account as a function of frequency.
CONV LOSS
TABLE
The CONV LOSS TABLE softkey opens a submenu for selecting and editing of con-
version loss tables. A list box containing all tables currently available opens by
pressing the softkey.
Remote command:
--
EDIT TABLE /
NEW TABLE
!
INSERT LINE
DELETE LINE
SAVE TABLE
PAGE UP /
PAGE DOWN
LOAD TABLE
!
PAGE UP /
PAGE DOWN
DELETE TABLE
COPY TABLE
PAGE UP /
PAGE DOWN