HFA3861AIN Intersil Corporation, HFA3861AIN Datasheet - Page 9

• Manufacturer Part Number: HFA3861AIN
• Description: Processor, Direct Sequence Spread Spectrum Base band Processor
• Manufacturer: Intersil Corporation

For the 1 and 2Mbps modes, the transmitter accepts data
from the external source, scrambles it, differentially encodes
it as either DBPSK or DQPSK, and spreads it with the BPSK
PN sequence. The baseband digital signals are then output
to the external IF modulator.
STANDBY
TX
RX
NO CLOCK
MODULATION
MODE
DQPSK
DBPSK
DATA
CCK
CCK
SYMBOL
Q
I vs Q
RATE
RATE
DATA
CHIP
I
OUT
OUT
Inactive
Inactive
RX_PE
Active
I
CC
1 BIT ENCODED TO
A/D SAMPLE CLOCK
802.11 DSSS BPSK
(TRUE-INVERSE)
Standby
ONE OF 2 CODE
11 CHIPS
BARKER
WORDS
11 MC/S
Inactive
Inactive
TX_PE
1 MS/S
1Mbps
Active
(MHz)
22
22
22
22
9
TABLE 3. BIT RATE TABLE EXAMPLES FOR MCLK = 44MHz
Inactive
Inactive
Inactive
RESET
Active
2 BITS ENCODED
TO ONE OF
4 CODE WORDS
44MHz
300µA
1.5mA
50mA
15mA
802.11 DSSS QPSK
TABLE 2. POWER DOWN MODES
AT
FIGURE 7. MODULATION MODES
TX SETUP CR 5
BITS 1, 0
BARKER
11 MC/S
2Mbps
1 MS/S
11 CHIPS
Both transmit and receive operations disabled. Device will resume its operational
state within 1µs of RX_PE or TX_PE going active.
Receiver operations disabled. Receiver will return in its operational state within 1µs
of RX_PE going active.
Transmitter operations disabled. Transmitter will return to its operational state within
2 MCLKs of TX_PE going active.
All inputs at V
00
01
10
11
HFA3861A
CC
For the CCK modes, the transmitter inputs the data and
partitions it into nibbles (4 bits) or bytes (8 bits). At 5.5Mbps,
it uses two of those bits to select one of 4 complex spread
sequences from a table of CCK sequences and then QPSK
modulates that symbol with the remaining 2 bits. Thus, there
are 4 possible spread sequences to send at four possible
or GND.
RX SIGNAL CR 63
SPREAD FUNCTIONS
4 BITS ENCODED
COMPLEX CCK
CODE WORDS
TO ONE OF 16
BITS 7, 6
5.5Mbps CCK
00
01
10
11
1.375 MS/S
COMPLEX
11 MC/S
8 CHIPS
DEVICE STATE
DATA RATE (Mbps)
5.5
11
1
2
SPREAD FUNCTIONS
8 BITS ENCODED
COMPLEX CCK
CODE WORDS
TO ONE OF 256
11Mbps CCK
1.375 MS/S
COMPLEX
11 MC/S
8 CHIPS
SYMBOL RATE
(MSPS)
1.375
1.375
1
1