RF109
2400 MHz Digital Spread Spectrum Transceiver
The RF109, a fully integrated transceiver device, provides the transmit, receive, and
frequency synthesis functions for 2400 MHz digital spread spectrum systems operating
in the 2400–2483.5 MHz portion of the ISM (Industrial, Scientific, Medical) band. The
device has a direct conversion architecture that minimizes circuit complexity and cost.
The receive path of the RF109 provides complete RF-to-baseband I/Q demodulation,
including an LNA, double-balanced quadrature mixers, fully integrated baseband filters,
and baseband variable-gain amplifiers. The transmit path is a variable-gain direct
conversion modulator. Figure 1 shows the RF109’s pin signals. Figure 2 shows the
RF109 block diagram.
The RF109 generates the Local Oscillator (LO) frequencies using a Phase Lock Loop
(PLL) frequency synthesizer and an external 2.4 GHz Voltage Controlled Oscillator
(VCO). The PLL provides a full frequency range of 2392.2–2505.6 MHz.
The RF109 features low-voltage operation (3.0–4.5V) for low power consumption. A
complete RF system solution for 2.4 GHz cordless telephone applications can be
constructed with the RF109, a power amplifier, a differential 2.4 GHz frequency source
and a Transmit/Receive (T/R) switch.
Features
•
Low power dissipation
•
Fast settling from standby mode to active
mode
•
Separate enable lines for transmit, receive,
and synthesizer
•
64 programmable channels with 1.8 MHz
channel spacing
•
3-battery-cell operation
•
48-pin TQFP package with exposed paddle
(refer to Figure 6)
•
Receiver
−
LNA/Quadrature
mixer from RF down to
baseband
−
Selectable LNA gain
−
Integrated baseband filter with external
bandwidth adjustment
−
Receiver baseband amplifier with
automatic gain control
−
Direct conversion with differential
baseband outputs
−
Low system noise figure (9.0 dB typical)
−
Large dynamic range (89 dB typical)
•
Transmitter
−
Variable gain modulator
−
Mixer for baseband-to-RF modulation
−
Differential TX inputs and outputs
−
Selectable transmitter output levels for
high, medium, and low power modes
NC1
CLK
FREF
DATA
TXREF
VCC1
VCC2
TXD
RXEN
LNAATTN
LNAIN
NC2
1
2
3
4
5
6
7
8
9
10
11
12
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
NC8
STROBE
SYNTHEN
VCC6
VCC5
CHPO
NC7
NC6
NC5
VCO2
VCO1
NC4
RF109
NC3
SRI+
SRI-
SRQ+
SRQ-
VCC4
GND3
RXI+
RXI-
RXQ+
RXQ-
VCC3
Applications
•
Digital Spread Spectrum (DSS) cordless
telephone
•
Direct sequence spread spectrum systems
•
Frequency hopping spread spectrum
systems
•
Wireless LANs
•
Wireless modems
•
Wireless security
•
Inventory control systems
Figure 1. RF109 Pin Signals
Data Sheet
GMCRES
GND1
RFO1
RFO2
GND2
TXEN
MIXBPC
MODSET
PS1
PS2
GCREF
AGC
13
14
15
16
17
18
19
20
21
22
23
24
Conexant Proprietary
Doc. No. 100646A
January 19, 2000
CONEXANT [ CONEXANT SYSTEMS, INC ]
