HSP50214BVI Intersil, HSP50214BVI Datasheet - Page 8

• Manufacturer Part Number: HSP50214BVI
• Manufacturer: Intersil

Specifications of HSP50214BVI

• Lead Free Status / RoHS Status: Not Compliant

the ability to change the received signal gain and frequency,
synchronous with burst timing. The synchronous gain
adjustment allows the user to measure the power of the signal
at the A/D at the end of a burst, and synchronously reload that
same gain value at the arrival of the next user burst.
For applications other than cellular phones (where the
preambles are not changed), the PDC frequency
discriminator output can be used to obtain correlation on the
preamble pattern to aid in burst acquisition.
Several applications are combinations of frequency and time
domain multiple access schemes. For example, GSM is a
TDMA signal that is frequency hopped. The individual
channels contain Gaussian MSK modulated signals. The
PDC again offers the 0.012Hz tuning resolution for de-
hopping the received signal. The combination of halfband
and 256-tap programmable, 22-bit coefficient FIR filters
readily performs the necessary matched filtering for
demodulation and optimum detection of the GMSK signals.
CDMA Based Standards and Applications
For Code Division Multiple Access (CDMA) type signals, the
PDC offers the ability to have a single wideband RF front
end, from which it can select a single spread channel of
interest. The synchronization circuitry provides for easy
control of multiple PDC for applications where multiple
received signals are required, such as base-stations.
In IS-95 CDMA, the receive signal bandwidth is
approximately 1.2288MHz wide with many spread spectrum
channel in the band. The PDC supplies the downconversion
and filtering required to receive a single RF channel in the
presence of strong adjacent interference. Multiple PDC’s
would be sourced from a single receive RF chain, each
processing a different receive frequency channel. The
despreader would usually follow the PDC. In some very
specific applications, with short, fixed codes, the filtering and
despreading may be possible with innovative use of the
programmable, 22-bit coefficient FIR filter. The PDC offers
0.012Hz resolution on tuning to the desired receive channel
and excellent rejection of the portions of the band not being
CHANNEL RATE (Kbps)
CHANNEL RATE (Kbps)
# TRAFFIC CHANNELS
TABLE 2. CELLULAR BASESTATION APPLICATIONS USING
VOICE MODULATION
CHANNEL BW (kHz)
BASESTATION RX
STANDARD
MODULATION
BAND (MHz)
TDMA
CONTROL
TYPE
935-960
Cellular
GMSK
GMSK
270.8
270.8
GSM
200
8
8
1805-1880
Cellular
GMSK
GMSK
270.8
270.8
PCN
200
16
824-849
DQPSK
DQPSK
Cellular
IS-54
48.6
48.6
π
π
30
3
/4
/4
HSP50214B
processed, via the halfband and 255-tap programmable, 22-
bit coefficient FIR filter.
Traditional Modulation Formats
AM, ASK, FM AND FSK
The PDC has the capability to fully demodulate AM and FM
modulated waveforms. The PDC outputs 15-bits of amplitude
or 16-bits of frequency for these modulation formats. The FM
discriminator has a 63-tap programmable, 22-bit coefficient FIR
filter for additional signal conditioning of the FM signal. Digital
versions of these formats, ASK and FSK are also readily
processed using the PDC. Just as in the AM modulated case,
ASK signals will use 15-bit magnitude output of the Cartesian to
Polar Coordinate converter. Multi-tone FSK can be processed
several ways. The frequency information out of the
discriminator can be used to identify the received tone, or the
filter can be used to identify and power detect a specific tone of
the received signal. AMPS is an example of an FM application.
PM AND PSK
The PDC provides the downconversion, demodulation,
matched filtering and coordinate conversion required for
demodulation of PM and PSK modulated waveforms. These
modulation formats will require external carrier and symbol
timing recovery loop filters to complete the receiver design.
The PDC was designed to interface with the HSP50210
Digital Costas Loop to implement the carrier phase and
symbol timing recovery loop filters (for continuous PSK
signals-not burst).
Digital modulation formats that combine amplitude and
phase for symbol mapping, such as m-ary QAM, can also be
downconverted, demodulated, and matched filtered. The
received symbol information is provided with 16-bits of
resolution in either Cartesian or Polar coordinates to
facilitate remapping into bits and to recover the carrier
phase. External Symbol mapping and Carrier Recovery
Loop Filtering is required for this waveform.
Resampling and Interpolation Filters
Two key features of the resampling FIR filter are that the re-
sampler filter allows the output sample rate to be
programmed with millihertz resolution and that the output
sample rate can be phase locked to an independent
separate clock. The re-sampler frees the front end sampling
clocks from having to be synchronous or integrally related in
rate to the baseband output. The asynchronous relationship
between front end and back end clocks is critical in
applications where ISDN interfaces drive the baseband
interfaces, but the channel sample rates are not related in
any way. The interpolation halfband filters can increase the
rate of the output when narrow frequency bands are being
processed. The increase in output rate allows maximum use
of the programmable FIR while preserving time resolution in
the baseband data.
May 1, 2007
FN4450.4