RF250 데이터 시트보기 (PDF) - Conexant Systems
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RF250 Datasheet PDF : 17 Pages
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Rx ASIC
RF250
Table 2. RF250 Signal Description (1 of 2)
Pin #
1
2
3
4
Name
GND
CELL_LNA_DECOUPLE
NC
CELL_LNA_IN
5
VCC1
6
CELL_BIAS_SET
7
CELL/PCS
8
FM/CDMA
9
VCC2
10
GND
11
CELL_TANK–
12
CELL_TANK+
13
PCS_TANK–
14
PCS_TANK+
15
DIV2/DIV4
16
PLL+
17
PLL–
18
GND
19
I–
20
I+
21
Q+
22
Q–
23
SLEEP
24
VGA_CONTROL
25
VCC3
26
VGA_CDMA_IN–
27
VGA_CDMA_IN+
28
VGA_AMPS_IN
Description
Ground
An RF bypass capacitor with very short trace should be connected to this pin.
No connection
The input to LNA needs external matching. The matching network should be placed as close
to this pin as possible. High Q components are recommended to minimize the effect on the
noise figure.
Supply voltage to the RF bias. An RF bypass capacitor should be connected from the pin to
ground with short traces..
This pin sets the cellular RF bias current. Typically, a 180 Ω resistor is connected from the
pin to ground.
Band select: 0 = cellular (800 MHz); 1 = PCS (1900 MHz).
Cellular band mode select: 0 = AMPS; 1 = CDMA.
Voltage supply pin to the VCO buffer. A bypass capacitor should be placed close to the
device from pin 9 to pin 10. The trace should be short and connected immediately to the
ground plane for best performance.
Ground return from the VCO buffer.
Differential tank connection for the cellular band VCO. Care should be taken during the
layout of the external tank circuit to prevent parasitic oscillations.
Differential tank connection for the cellular band VCO. Care should be taken during the
layout of the external tank circuit to prevent parasitic oscillations.
Differential tank connection for the PCS band VCO. Care should be taken during the layout
of the external tank circuit to prevent parasitic oscillations.
Differential tank connection for the PCS band VCO. Care should be taken during the layout
of the external tank circuit to prevent parasitic oscillations.
Selects the divide ratio of the VCO to the LO port of the I/Q demodulator: 0 = divide by 2,
1 = divide by 4.
Differential buffered VCO output.
Differential buffered VCO output.
Ground
I channel differential output.
I channel differential output.
Q channel differential output.
Q channel differential output.
Activates sleep mode: 0 = sleep; 1 = enable
VGA voltage input. Input impedance is greater than 50K Ω.
Voltage supply to VGA and I/Q demodulator stages. Supply should be well regulated and
bypassed to prevent modulation of the signal by the supply ripple.
CDMA differential VGA input
CDMA differential VGA input
AMPS VGA input.
4
Conexant Systems, Inc.
101251A
August 24, 2000
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