Preliminary
RF2721
Pin
10
Function Description
Interface Schematic
See pin 8.
Demodulated baseband I output. The reference DC level of this pin is
set by the voltage of pin 9 (REF IN), which is connected to this pin
through a 5kΩ resistor to the collectors of this push-pull output. This
results in an output impedance of 5kΩ if the REF IN pin is connected to
a low impedance source. The capacitance of the load determines the
maximum baseband frequency. A very low capacitive load may stretch
the 3dB bandwidth over 10MHz. Another way to increase bandwidth is
by connecting a shunt resistor. This will trade gain for bandwidth.
I OUT
Same as pin 2.
11
12
GND
PD
Power down control. When this pin is "low", all circuits are shut off. A
"low" is typically 0.8V or less at room temperature. When this pin is
"high", all circuits are operating normally.
VCC
PD
Power supply pin. An external 100nF bypass capacitor is recom-
mended if no other bypass capacitor is nearby.
13
14
VCC
Balanced IF input. An input level of 400mV gives full output swing; a See pin 1.
IF IN-
PP
level of maximum 250mV is recommended for linear operation. This
PP
pin has no internal DC block and an external capacitor of 100nF is
needed if connected to a DC path. If the IF is driven by a single-ended
source, connect this pin to an 100nF capacitor to ground.
7
2-30
Rev A2 010509
RFMD [ RF MICRO DEVICES ]
