3
dc961bf
DEMO MANUAL DC961B
Quick test proceDure
Figure 4. Input and Output Common Mode Quick Test Setup
B. DC Coupled Inputs and Output Common Mode
Voltage Adjustment
1. On the DC961, install 0603 0Ω resistors at R1 and R10
to short input capacitors C8 and C12 respectively (see
DC961 schematic).
2. Connect DC961 as shown in Figure 4 (JP1 to PWR_ON,
JP2 to SINGLE, and JP3 to EXT V
OCM
).
3. Apply an input signal with a DC offset (V
IN
CM) 0V to
V
+
–1.25V. The output common mode (V
OCM
) can be
set independently of the V
IN
CM from 1.1V to V
+
–0.8V.
This adjustment is made by applying a DC voltage at
EXT V
OCM
.
V
+
3
6
1
2
7
PWR_ON
JP1
SHDN
8
5
4
0.1µF
LT1994
V
OCM
0.1µF
R12, 50Ω
J3
J4
CH1
CH2
CH2
OSCILLOSCOPE
CH1
R15, 50Ω
R4
499Ω
DC961b F04
0.1µF
499Ω
V
OUT
+
SMA
TO
BNC
24 INCHES OR
LESS OF COAX CABLE
DC961 JUMPERS SETTINGS:
JP1 LT1994, SHDN PIN TO GND OR OPEN
JP2 LT1994, V
–
PIN TO V
–
OR GND
JP3 LT1994, V
OCM
PIN TO V
+
/2 OR
AN EXTERNAL CONNECTION
SET OSCILLOSCOPE
TRIGGER TO CH2
SMA
TO
BNC
J2
BNC
TO
SMA
V
OUT
–
JP2
SINGLE
DUAL
R8
499Ω
R6
C12, 1µF
0Ω
0Ω
R5
JP3
EXT
10k
10k
V
+
V
–
INT
EXT
V
OCM
100Ω
Z2
R9
499Ω
R2
C8, 1µF
FUNCTION
GENERATOR
V
IN
CM
V
IN
–
50Ω
TERMINATION
V
OCM
VOLTAGE
SOURCE
J1
BNC
TO
SMA
V
IN
+
50Ω
OUTPUT
IMPEDANCE
SET FUNCTION GENERATOR
TO A 1V
P-P,
100kHz SINEWAVE
WITH VARIABLE DC OFFSET
REGISTOR
JUMPER
REGISTOR
JUMPER
0V ≤ V
IN
CM ≤ V
+
–1.25V
1.1V ≤ V
OCM
≤ V
+
–0.8V
R1, 0Ω
0Ω
0Ω
Z1
1.1V ≤ V
OCM
≤ V
+
–0.8V
1.1V ≤ V
OCM
≤ V
+
–0.8V
3V TO 5V
V
+
V
–
TO JP2
DC961
–
+
–
+
R10, 0Ω
V
OCM
