HFA3861B Просмотр технического описания (PDF) - Intersil
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HFA3861B Datasheet PDF : 36 Pages
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IREF (21)
VREF (16)
TX_AGC_IN (18)
TX_IF_AGC (35)
ANTSEL (39)
ANTSEL (40)
VDD (ANALOG)
(12, 17, 22, 31)
HFA3861B
GND (ANALOG)
(9, 15, 20, 25, 28)
VDD (DIGITAL)
(2, 8, 37, 57)
GND (DIGITAL)
(1, 7, 36, 43, 56)
6-BIT
ADC
6-BIT
DAC
TX AGC
CONTROL
REGISTER
TRANSMIT
FILTER
DAC
DAC
PREAMBLE/HEADER
CRC-16
GENERATOR
MODULATOR,
BARKER/CCK
TX_DATA
SCRAMBLER
(52) RXCLK
(60) CCA
TXI (23, 24)
TXQ (29, 30)
(59) TX_RDY
(55) TXCLK
(58) TXD
TIMING
GENERATOR
MCLK
TX
STATE
CONTROL
TEST PORT
(3) SD
(4) SCLK
(64) SDI
(5) R/W
(6) CS
(62) TX_PE
(42)
MCLK
(44) (45) (46) (47) (48) (49) (50) (51)
FIGURE 11. DSSS BASEBAND PROCESSOR, TRANSMIT SECTION
PN Correlators Description
There are two types of correlators in the HFA3861B baseband
processor. The first is a parallel matched correlator that
correlates for the Barker sequence used in preamble, header,
and PSK data modes. This PN correlator is designed to handle
BPSK spreading with carrier offsets up to ±50ppm and 11 chips
per symbol. Since the spreading is BPSK, the correlator is
implemented with two real correlators, one for the I and one for
the Q Channel. The same Barker sequence is always used for
both I and Q correlators.
These correlators are time invariant matched filters otherwise
known as parallel correlators. They use one sample per chip for
correlation although two samples per chip are processed. The
correlator despreads the samples from the chip rate back to the
original data rate giving 10.4dB processing gain for 11 chips per
bit. While despreading the desired signal, the correlator
spreads the energy of any non correlating interfering signal.
The second form of correlator is the correlator function used for
detection of the CCK modulation. For the CCK modes, the
correlation function uses a Fast Walsh Transform to correlate
the 4 or 64 code possibilities followed by a biggest picker. The
biggest picker finds the biggest of 4 or 64 correlator outputs
depending on the rate. This is translated into 2 or 6 bits. The
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