HFA3863 Просмотр технического описания (PDF) - Intersil
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HFA3863 Datasheet PDF : 39 Pages
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IREF (21)
VREF (16)
TX_AGC_IN (18)
TX_IF_AGC (35)
ANTSEL (39)
ANTSEL (40)
HFA3863
VDD (ANALOG)
(12, 17, 22, 31)
GND (ANALOG)
(9, 15, 20, 25, 28)
VDD (DIGITAL)
(2, 8, 37, 41, 57)
GND (DIGITAL)
(1, 7, 36, 43, 56)
6-BIT
ADC
6-BIT
DAC
TX AGC
CONTROL
REGISTER
TRANSMIT
FILTER
PREAMBLE/HEADER
CRC-16
GENERATOR
DAC
DAC
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
Channel Matched Filter (CMF) Description
The receive section shown in Figure 13 operates on the
RAKE receiver principle which maximizes the SNR of the
signal by combining the energy of multipath signal
components. The RAKE receiver is implemented with a
Channel Matched Filter (CMF) using a FIR filter structure
with 16 taps. The CMF is programmed by calculating the
Channel Impulse Response (CIR) of the channel and
mathematically manipulating that to form the tap coefficients
of the CMF. Thus, the CMF is set to compensate the channel
characteristics that distort the signal. Since the calculation of
the CIR is inaccurate at low SNR or in the presence of strong
CW interference, the chip has thresholds (CR 36 to 39) that
are set to substitute a default CMF shape under those
conditions. This default CMF shape is designed to
compensate only the known transmit and receive non
linearity.
PN Correlators Description
There are two types of correlators in the HFA3863 baseband
processor. The first is a parallel matched filter correlator that
correlates for the Barker sequence used in preamble,
header, and PSK data modes. This Barker code 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
4-16
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