RF9958 Datasheet, PDF (6/12 Pages) RF Micro Devices – CDMA/FM TRANSMIT MODULATOR, IF AGC, AND UPCONVERTER

RF9958
Pin
22
23
24
Function
MIX IN+
GND2
MOD OUT-
Description
Interface Schematic
Same as pin 21, except complementary input.
See pin 21.
Same as pin 16.
One half of the balanced AGC output port. The impedance of this port
is 200Ω balanced. If no filtering is required, this pin can be connected
to the MIX IN- pin through a DC blocking capacitor. This pin requires an
inductor to V_CC to achieve full dynamic range. In order to maximize
gain, this inductor should be a high-Q type and should be parallel reso-
nated out with a capacitor (see application schematic). This pin is NOT
DC blocked. A blocking capacitor of 2200pF is needed when this pin is
connected to a DC path. An appropriate matching network may be
needed if an IF filter is used.
V_CC3
V_CC3
100 Ω
100 Ω
MOD OUT-
MOD OUT+
25 MOD OUT+ ^{Same as pin 24, except complementary output.}
See pin 24.
5
26
DEC
AGC decoupling pin. An external bypass capacitor of 10nF capacitor is
required. The trace length between the pin and the bypass capacitors
should be minimized. The ground side of the bypass capacitors should
connect immediately to ground plane.
27
GC
Analog gain control for AGC amplifiers. Valid control voltage ranges are
from 0.5V_DC to 2.5V_DC. The gain range for the AGC is 88dB. These
voltages are valid ONLY for a 37kΩ source impedance. A DC voltage
less than or equal to the maximum allowable Vcc may be applied to this
pin when no voltage is applied to the Vcc pins.
BIAS
21 kΩ
GC
40 kΩ
28
VCC2
Supply for the modulator stage only. A 10nF external bypass capacitor
is required and an additional 0.1µF will be required if no other low fre-
quency bypass capacitors are nearby. The trace length between the pin
and the bypass capacitors should be minimized. The ground side of the
bypass capacitors should connect immediately to ground plane.
5-98
Rev B11 010720