LTC6406
12
6406fc
APPLICATIONS INFORMATION
Figure 1. DC Test Circuit
–
+
1
SHDN
5
6
–IN
7
+OUT
8
+OUTF
16
15
+IN
VTIP
NC
14
–OUT
100k
13
–OUTF
V–OUTF
RF
CF
V+OUTF
V–OUT
V+OUT
2
V+
3
V–
V+
V–
V+
V–
4
VOCM
VSHDN
VVOCM
VOCM
12
V–
11
V+
10
V+
9
V–
V –
V–
CF
V–
6406 F01
LTC6406
SHDN
0.1μF
0.01μF
VCM
RF
RI
RBAL
100k
RBAL
100k
+
–
VINP
–
+
VINM
V–IN
V+IN
VOUTCM
V+
0.1μF
1.25pF
0.1μF
0.01μF
50Ω
Functional Description
The LTC6406 is a small outline, wideband, low noise, and
low distortion fully-differential amplier with accurate
output phase balancing. The LTC6406 is optimized to
drive low voltage, single-supply, differential input analog-
to-digital converters (ADCs). The LTC6406 input common
mode range is rail-to-rail, while the output common mode
voltage is independently adjustable by applying a voltage
on the VOCM pin. The output voltage swing extends from
near ground to 2V, to be compatible with a wide range of
ADC converter input requirements. This makes the LTC6406
ideal for level-shifting signals with a wide common mode
range for driving 12-bit to 16-bit single supply, differential
input ADCs. The differential output allows for twice the
signal swing in low voltage systems when compared to
single-ended output ampliers. The balanced differential
nature of the amplier also provides even-order harmonic
distortion cancellation, and less susceptibility to common
mode noise (like power supply noise). The LTC6406 can be
used as a single-ended input to differential output amplier,
or as a differential input to differential output amplier.
The LTC6406 output common mode voltage, dened as the
average of the two output voltages, is independent of the
input common mode voltage, and is adjusted by applying
a voltage on the VOCM pin. If the pin is left open, there
is an internal resistive voltage divider, which develops a
potential of 1.25V (if the supply is 3V). It is recommended
that a high quality ceramic capacitor is used to bypass the
VOCM pin to a low impedance ground plane. The LTC6406’s
internal common mode feedback path forces accurate