Datasheet

AD604
Rev. G | Page 25 of 32
PREAMPLIFIER GAIN
The default gain of the preamplifier is 20 dB, 14 dB is achieved
with 0  resistors in the R11and R12 positions. The 14 dB and
20 dB preset gains are accurate because of the close matching of
the internal thin film resistors. The gain accuracy after installing
external resistors is subject to inherent tolerance of absolute
accuracy; however, any pair of preamplifiers is reasonably
matched when standard 1% SM resistors are used.
OUTPUTS
The DSX outputs are available on the OUT1 and OUT2 SMA
connectors and are series terminated with decoupling capacitors
and 49.9  series resistors.
DC OPERATING CONDITIONS
Table 4 lists the trimmers and their functions provided for
convenient dc level adjustments of gain, reference voltage, and
output common-mode voltage. Table 5 lists the switches and
their functions.
Table 4. Trimmer Functions
Trimmer Function
GN1_ADJ Optional dc level for VGA Channel 1
VREF_ADJ Optional dc level to adjust reference voltage
VOCM_ADJ Output common-mode voltage adjustment
GN2_ADJ Optional dc level for VGA Channel 2
Table 5. Jumpers
Switch Function
VG1−IN Connects –DSX1 to the SMA connector VGA1−IN or to ground.
VG1+IN Connects +DSX1 (ac-coupled) to the preamplifier output of Channel 1 (PAO1) or to the SMA connector VGA1+ IN.
CH1 Enables/disables Channel 1 preamp by connecting COM1 to ground (enable) or to +5V (disable).
CH2 Enables/disables Channel 2 preamp by connecting COM2 to ground (enable) or to +5V (disable).
VG2+IN_SW
Connects the +DSX input to the SMA VGA2+IN, the Channel 2 preamplifier output (PAO2), or the output of Channel 1 for
a cascade connection.
VG2−IN Connects –DSX2 to SMA VGA2−IN or to ground.
GN1 Connects the VGN1 input to trimmer GN1_ADJ gain adjust wiper or leaves the input unconnected.
REF Connects the reference input to the VREF_ADJ trimmer or leaves the input connected.
OCMV Connects VOCM to the common-mode voltage trimmer, VOCM_ADJ.
00540-157
OSCILLOSCOPE TO
MONITOR VOUT
POWER SUPPLY
FUNCTION
GENERATOR SINE
INPUT
Figure 57. A Representative Test Setup of the AD604-EVALZ