HSP50307EVAL1(1996) Просмотр технического описания (PDF) - Intersil
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HSP50307EVAL1 Datasheet PDF : 8 Pages
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HSP50307
Control Interface
Synthesizer
The QPSK modulator is configured via a serial three wire
interface. When C_EN is high, 23 bits are shifted in at the
CDATA pin on the falling edge of CCLK. Figure 3 shows the
timing diagram for loading the serial configuration data.
Table 1 describes the 23-bit serial configuration data. See
the Synthesizer Section for more details on the frequency
control bits.
TABLE 1. 23-BIT SERIAL DATA CONTROL INTERFACE
DESCRIPTION
BIT
POSITION FUNCTION
DESCRIPTION
The synthesizer generates the quadrature LO’s for
modulating the baseband data to RF. The carrier frequency
is phase locked to the reference clock (RCLK). The carrier
frequency, FC, has a frequency range of 8MHz to 15MHz
with a resolution of 32kHz. Equation 1 gives the relationship
between FC and the frequency of RCLK and the frequency
control bits, M and A.
FC = 6----(---M------+-6---4-1----)---+-----A--- FREF ,
(EQ. 1)
where FREF equals the frequency of RCLK. Also, M and A
can be determined by
D0-D2
(Note)
D3-D9
D10
D11
D12
D13-D18
D19-D21
D22
Synthesizer Pre-scaler control register.
Control Bits A = (0 to 5), D2 is the MSB.
Synthesizer Feedback Counter Control Register.
Control Bits M = (41 to 103) D9 is the MSB.
Synthesizer
Enable
Active high. This bit activates chip bias
networks for normal operation. D10 = 0
places part in low power mode.
ChargePump D11 = 0 sets charge pump current to
Current
500µA.
Control
D11 = 1 sets charge pump current to
1mA.
Three-State
Control
D12 = 0 three-states the charge pump
output when a pump up and down
command occur simultaneously.
D12 = 1 disables three-state.
Attenuation
Control
Controls output power level. The bina-
ry value of the register corresponds to
an attenuation amount. For example,
000100 corresponds to 4dB attenua-
tion from the maximum 62dBmV level.
D18 is the MSB.
Reserved
Used for test/diagnostic purposes.
Set to 000.
DSP Shut
Down
Test mode; D22 = 0 sets the burst
QPSK modulator in normal mode.
D22 = 1 disables the digital filter.
M + A-6-- = 6--6--4-- F----FR----C-E----F- – 1.
(EQ. 2)
“A” ranges from 0 to 5 and “M” ranges from 41 to 103. A and
M are programmed via control bits D0-D2 and D3-D9,
respectively. Values outside these ranges are invalid.
I/Q Generator
The I/Q Generator Section demultiplexes and time aligns the
256 KBPS input data into two data streams, I and Q. The
first data bit following the assertion of the TX_EN signal is
the I data of the first I/Q pair. Each I/Q pair determines the
phase angle of the QPSK transmission signal. The relation-
ship between I/Q pairs and phase angles is shown in
Table 2. Since the QPSK encoding requires a pair of I and Q
information to transmit one symbol, an even number of data
bits must be provided for each burst.
TABLE 2. QPSK ENCODING
I
Q
PHASE
0
0
45o
0
1
135o
1
0
-45o
1
1
-135o
NOTE: D0 is the first bit shifted into the part.
tCCH
CCLK
C_DATA
C_EN
tCDS
tCDH
D22
D21
D20
D19
D3
D2
D1
D0
FIGURE 3. CONTROL INTERFACE TIMING DIAGRAM
7-71
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