4
dc2319af
DEMO MANUAL DC2319A
Single-Ended Input to Differential Output
To configure the DC2319A for single-ended input to
differential output, simply connect a DC bias (such as
ground) to VIN
–
and connect the input signal to VIN
+
.
The differential output is measured on VOUT
+
and VOUT
–
.
The unused input can also be grounded on the board by
populating R13 or R14.
Differential Input to Differential Output
To configure the DC2319A for differential input to differ-
ential output, simply connect the differential input signal
to VIN
+
and VIN
–
respectively. The differential output is
measured on VOUT
+
and VOUT
–
.
AC-Coupled Applications
In the default configuration, both the inputs and outputs of
the DC2319A are DC-coupled. To AC-couple the DC2319A,
at either the inputs or outputs or both, simply replace
the 0Ω resistors R5/R6/R11/R12 with appropriate value
0603 capacitors.
External Output Common Mode Adjust
The DC2319A is by default configured to bias the output
common mode at the voltage determined by the LTC6363
IC, which is at approximately the mid-point between the
amplifier’s V
+
and V
–
pins. (For example, if single supply
is used, the output common mode will be at half the V
+
voltage).
To set a different value for the output common mode
voltage, populate resistors R15 and R16. This will form a
resistor divider in parallel with the resistor divider internal
to the LTC6363 IC.
The most accurate way to set the output common mode
voltage is by applying the desired DC bias to the EXT
VOCM pin at E5. This will overdrive any of the on-chip or
onboard resistor dividers.
Input or Output Filters
There are many 0Ω resistors and non-installed resistors or
capacitors on the DC2319A board which can be populated
by appropriate R and C values to configure lowpass filters
at the inputs or outputs of the amplifier circuit.
Active Feedback Filters
Various optional feedback components (such as R17,
R18, C15, C16, C17, C18) can be populated to configure
differential active feedback filters. This is most relevant
for the DC2319A-A (the version of LTC6363 without in-
ternal gain suffix). The other versions (with internal gain
resistors) do not provide access to the internal amplifier
feedback nodes, so that it is not possible to configure
external feedback filters. See Table 1.
Layout
The DC2319A PCB layout demonstrates the known best-
practices of PCB layout to get the best performance out of
the LTC6363. A ground plane is used, and supply bypass
capacitors are close to the supply pins. Use a symmetrical
layout around the analog inputs and outputs to minimize
the effects of parasitic elements. Shield analog input and
output traces with ground to minimize coupling from other
traces. Feedback traces are as short as possible.
Nevertheless, the DC2319A is a general purpose ap-
plications board with many placeholders for optional
components. After proto-typing a specific design on the
DC2319A, a final PCB layout can be further optimized by
removing the placeholders for the unused components. In
addition, the DC2319A is designed to accommodate both
single supply and dual supply circuits. A PCB design for
a single supply application would connect the amplifier’s
V
–
pin directly to the copper ground plane and use only one
supply bypass capacitor directly between V
+
and ground.
harDware configuration
