hsp50306 Intersil Corporation, hsp50306 Datasheet - Page 5

• Manufacturer Part Number: hsp50306
• Description: Digital Qpsk Demodulator
• Manufacturer: Intersil Corporation

Two Versions: Different Applications
The -27 and -25 versions of the HSP50306 Digital QPSK
Demodulator are not simply different speed grades of the
same device, but are designs which have proportionally
scaled clocks and bandwidths for different applications.
NOTE: While these parts are pin for pin compatible, in
most applications they cannot be used as functional
equivalent substitutes for each other. Key differences are:
• The -27 version of the HSP50306 has an input IF of
• The -25 version of the HSP50306 has an input IF of
In both the -27 and -25 designs, the sample rate clock for the
input IF signal is half of the CLK frequency. NOTE: Sample
rate clock is designated by f
IF and input clock, all other performance parameters of the
two parts are identical for their respective IF inputs.
10.7MHz Input IF Applications
Both the -27 and -25 parts can be used in 10.7MHz IF Applica-
tions. Figures 3 and 4 show the frequency spectrum for the
sampled 10.7MHz IF input signals for both the -27 and -25 ver-
sions, respectively. In the 10.7MHz IF Application, the -25 ver-
sion offers tighter filtering capability than the -27 version
because the lower IF allows use of low pass filtering. Also, the
lower IF of the -25 version has inherently lower internal pro-
cessing spectral spurs than the -27 version. Note that the
receive IF for the HSP50306SC-27 is the input IF to the demod-
ulator. For the HSP50306SC-25, the receive IF is 10.7MHz, but
the processing is done on the spectral image at 2.1MHz. Exam-
ine the spectral inversion between the 10.7MHz Receive IF and
the 2.1MHz demodulator input in Figure 4. The transmit differ-
ential encoder must take into account this spectral rever-
sal. The required encoding is shown in Table 3. This part was
designed to be paired with the HSP50307 Burst Modulator, and
can be operated from the same 25.6MHz reference clock.
10.7MHz with an input clock of 26. 97MHz.
2.1MHz with an input clock of 25. 6MHz.
S
= f
CLK
/2. Aside from input
HSP50306
8-276
TABLE 3. DIFFERENTIAL ENCODING REQUIRED FOR THE -27
DC
DC
FIGURE 3. SAMPLED SPECTRUM FOR THE -27 VERSIONS
FIGURE 4. SAMPLED SPECTRUM FOR THE -25 VERSIONS
INPUT
BITS
2.79
DEMOD INPUT IF
2.1
00
01
10
11
RECEIVE IF
AND -25 DEMODULATORS RECEIVING 10.7MHz IF
(f
(f
CLK
CLK
REQUIRED FOR -27
DEMODULATION
PHASE CHANGE
= 26.97MHz)
= 25.6MHz)
10.7 F
10.7 F
180
-90
RECEIVE IF
90
0
DEMOD INPUT IF
S
o
o
S
o
o
14.9
16.27
REQUIRED FOR -25
DEMODULATION
PHASE CHANGE
24.19 F
23.5 F
180
-90
90
CLK
CLK
0
o
o
o
o
27.7
29.76