Additional Information - Linear Technology DC1464A Quick Start Manual

DEMO CIRCUIT DC1464 QUICK START GUIDE FOR LTC6412

ADDITIONAL INFORMATION

SHUTDOWN AND ENABLE
The factory default configuration is set for the power-on
and amplifier-enabled state (SHDN=1, EN=0).
SHDN pin is pulled high with a 1kΩ resistor to V
the EN pin is pulled low with a 1kΩ resistor to ground.
One can override these board-level defaults by applying
voltages directly to the SHDN and EN turrets as needed.
–V AND +V CONTROL
G G
The factory default configuration is set for –V
with the V SMA connector hooked in parallel with the
GAIN
–V turret. These control inputs can be reconfigured for
G
+V operation by moving jumper R15 to location R14
G
and moving jumper R19 to location R18. Clip leads to
the ±V turrets are susceptible to noise pickup and
G
should be lowpass filtered to avoid AM up-conversion
artifacts. While using the ±V
from the V SMA terminal to ground provides an ef-
GAIN
fective lowpass filter with a cutoff frequency of 340 Hz.
DIFFERENTIAL INPUTS
The inputs connectors can be configured for differential
drive. Remove the jumper in location R9 to enable dif-
ferential input drive (50 Ohm).
Alternatively, the input balun T1 can be removed com-
pletely and the ±IN signals routed directly to C5 and C8
using 0603 0Ω jumpers across the input balun pads.
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The
, and
CC
control
G
turrets, a 4.7µF capacitor
G
DIFFERENTIAL OUTPUTS
The output connectors can be configured for differential
drive. Move capacitor C21 to location C9 to enable dif-
ferential output drive (50 Ohm).
Alternatively, the output balun can be removed com-
pletely with the ±OUT signals routed to LTC6412 output
pins using 0Ω 0603 jumpers across the output balun
pads as shown below. This transformerless configura-
tion requires two additional inductors from the balun
center tap pad to conduct supply current to the LTC6412
output pins. The inductors should choke the RF signal
sufficiently at the frequency of interest while passing DC
current with minimal supply drop, <100mV is recom-
mended. A surface mount 0603 inductor is a good size
choice to bridge the PCB pad gap. Keep the DC blocking
capacitors at C6 and C9 to avoid a DC path to the output
SMA connectors.
TURRET OPTIONS
Turrets to V , DECL_1, and DECL_2 are usually not
CM
stuffed as they represent internal voltages generated by
LTC6412. Do not connect to these nodes beyond the
recommended bypass capacitors to ground.
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