HFA3724
Data Sheet
November 1999
File Number
4067.7
400MHz Quadrature IF
Modulator/Demodulator
The Intersil 2.4GHz PRISM™ chip set is a
highly integrated five-chip solution for RF
modems employing Direct Sequence
Spread Spectrum (DSSS) signaling. The
HFA3724 400MHz Quadrature IF
Modulator/Demodulator is one of the five chips in the PRISM™
chip set (see the Typical Application Diagram).
™
Features
• Integrates all IF Transmit and Receive Functions
• Broad Frequency Range . . . . . . . . . . . 10MHz to 400MHz
• I/Q Amplitude and Phase Balance . . . . . . . . . . . 0.2dB, 2
o
• 5th Order Programmable
Low Pass Filter. . . . . . . . . . . . . . . . . . . 2.2MHz - 17.6MHz
• 400MHz Limiting IF Gain Strip with RSSI. . . . . . . . . .84dB
• Low LO Drive Level . . . . . . . . . . . . . . . . . . . . . . . -15dBm
• Fast Transmit-Receive Switching . . . . . . . . . . . . . . . . . 1µs
• Power Management/Standby Mode
• Single Supply 2.7V to 5.5V Operation
The HFA3724 is a highly integrated baseband converter for
quadrature modulation applications. It features all the necessary
blocks for baseband modulation and demodulation of I and Q
signals. It has a two stage integrated limiting IF amplifier with 84db
of gain with a built in Receive Signal Strength Indicator (RSSI).
Baseband antialiasing and shaping filters are integrated in the
design. Four filter bandwidths are programmable via a two bit
digital control interface. In addition, these filters are continuously
tunable over a
±20%
frequency range via one external resistor. The
modulator channel receives digital I and Q data for processing. To
achieve broadband operation, the Local Oscillator frequency input
is required to be twice the desired frequency of
modulation/demodulation. A selectable buffered divide by 2 LO
output and a stable reference voltage are provided for convenience
of the user. The device is housed in a thin 80 lead TQFP package
well suited for PCMCIA board applications.
Applications
• Systems Targeting IEEE 802.11 Standard
• TDD Quadrature-Modulated Communication Systems
• Wireless Local Area Networks
• PCMCIA Wireless Transceivers
• ISM Systems
• TDMA Packet Protocol Radios
Ordering Information
PART NUMBER
HFA3724IN
HFA3724IN96
TEMP. RANGE
(
o
C)
-40 to 85
-40 to 85
PACKAGE
80 Ld TQFP
Tape and Reel
PKG. NO.
Q80.14x14
• PCS/Wireless PBX
• Wireless Local Loop
Simplified Block Diagram
LPF_RX_Q
LPF_RX_I
LPF_TUNE_1
LPF_TUNE_0
MOD_RX_I
MOD_RX_Q
LIM2_OUT
MOD_IF_IN
LPF_SEL0
LPF_SEL1
LPF_RXI_OUT
LPF_RXQ _OUT
MOD_LO_IN
÷2
MOD_LO_OUT
LO_GND
MOD_TX_IF_OUT
2V
REF
MOD_TX_Q
MOD_TX_I
LPF_TX_Q
LPF_TX_I
2V REF
∑
0
o
/90
o
M
U
X
I
M
U
X
LPF_TXI_IN
LPF_TXQ_IN
LIM1_OUT
LIM2_IN
LIM1_IN
RSSI1
RSSI2
IF
IF
Q
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
|
Copyright
©
Intersil Corporation 1999
PRISM® is a registered trademark of Intersil Corporation. PRISM logo is a trademark of Intersil Corporation.
HFA3724
Typical Application Diagram
HFA3724
(FILE# 4067)
TUNE/SELECT
HSP3824
(FILE# 4064)
RXI
DATA TO MAC
CTRL
SPREAD
DPSK
MOD.
PRISM™ CHIP SET FILE #4063
HFA3424
(NOTE)
(FILE# 4131)
A/D
DE-
SPREAD
DPSK
DEMOD
HFA3624
RF/IF
CONVERTER
(FILE# 4066)
I
RXQ
A/D
CCA
802.11
MAC-PHY
INTERFACE
÷
2
0
o
/90
o
M
U
X
M
U
X
RSSI
A/D
TXI
RFPA
HFA3925
(FILE# 4132)
VCO
VCO
TXQ
Q
QUAD IF MODULATOR
DUAL SYNTHESIZER
DSSS BASEBAND PROCESSOR
HFA3524
(FILE# 4062)
TYPICAL TRANSCEIVER APPLICATION USING THE HFA3724
NOTE: Required for systems targeting 802.11 specifications.
For additional information on the PRISM™ chip set, call
(407) 724-7800 to access Intersil’ AnswerFAX system. When
prompted, key in the four-digit document number (File #) of
the datasheets you wish to receive.
The four-digit file numbers are shown in Typical Application
Diagram, and correspond to the appropriate circuit.
4
HFA3724
Typical Application Diagram
V
CC
0.1
75
PE
74
2
260
3
1
4
100p
77
76
100p
80
(NOTE 2)
8 TO 40p
10nH
100p
V
CC
0.1
55
100p
560
0.1
100p
62
63
61
100p
64
100p
59
(NOTE 3)
CONVERTER
HFA3624IA
47p 220 44
LO_IN
56
47p
35 0.01 28
36
0.01
18
900
19
(NOTE 5)
46
37
0.1
TOYOCOM
TQS 432
IF/RF
TX_IF_OUT
47nH
V
CC
316
42
38
0.01
39 0.01 24
40
50
NC
560MHz
VCO (AUXILIARY)
43
41
0.01
22
23
0.01
10
2V REF
26
25
12
4.3K
680
0.1
11
680
TXQ
13 4.3K
LPF_TX_PE
LPF_RX_PE
21
TXI
0.1
16 LPF_SEL1
V
CC
17 LPF_SEL0
27
PE
54
57 100p
56
1K
45
48
49
47
9
RXI_OUT
0.01
14
0.1
(Targeting IEEE 802.11 Standard)
V
CC
0.1
V
CC
RSSI
TOYOCOM
TQS 432
RF/IF
(NOTE 1)
100p
56n
33 0.01 30
34
0.01
29
0.1
100p
100p
60 100p
47p
79
RXQ_OUT
0.01
15
20
BASEBAND PROCESSOR
HSP3824VI
(NOTE 6)
100p 47
100p (NOTE 4)
VCO
DUAL SYNTHESIZER
HFA3524IA
TYPICAL APPLICATION DIAGRAM (TARGETING IEEE 802.11 STANDARD)
NOTES:
1. Input termination used to match a SAW filter.
2. Typical bandpass filter for 280MHz, BW = 47MHz, Q = 6. Can also be used if desired after the second stage.
3. Network shown for a typical -10dBm input at 50Ω.
4. Output termination used to match a SAW filter.
5. R
TUNE
value for a 7.7MHz cutoff frequency setting.
6. LO buffer output termination is needed only when the buffer is enabled by pin 50 connected to GND, otherwise tie pin 46 to pin 47.
5
MOD_RX_PE
MOD_TX_PE
Analog electronics
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