RF25A-12 데이터 시트보기 (PDF) - Conexant Systems
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RF25A-12 Datasheet PDF : 17 Pages
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RF25A
Pin #
1
2
Name
NC
LNA_DECOUPLE
Table 1. RF25A Pin Assignments and Signal Descriptions (1 of 3)
Description
No connection.
An RF bypass capacitor (1000 pF) with very short trace should be connected to this pin.
Rx ASIC
Equivalent Circuit
3
NC
4
LNA_IN
5
VCC_RFBIAS
6
BIAS_SET
7
FM/CDMA
8
VCC_VCO
9
GND
10
TANK-
11
TANK+
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. A DC blocking capacitor is necessary at the input.
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.
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 8 to pin 9. 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.
12
NC
No connection.
13
DIV2/DIV4
Selects the divide ratio of the VCO to the LO port of the I/Q demodulator: 0 = divide by 2,
1 = divide by 40.
14
PLL+
Differential buffered VCO output
Vcc
Vcc
–
+
15
PLL-
Differential buffered VCO output
16
I+
17
I-
18
Q+
19
Q-
20
SLEEP
4
I channel differential output.
I channel differential output.
Q channel differential output.
Q channel differential output.
Activates sleep mode: 0 = sleep; 1 = enable
Conexant – Preliminary.
Proprietary Information
1011110A
August 4, 2000
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