HSP50214BVCZ datasheet(7/62 Pages) RENESAS

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HSP50214B

FN4450 Rev 4.00

Page 7 of 62

May 1, 2007

Functional Description

The HSP50214B Programmable Downconverter (PDC) is an

agile digital tuner designed to meet the requirements of a

wide variety of communications industry standards. The

PDC contains the processing functions needed to convert

sampled IF signals to baseband digital samples. These

functions include LO generation/mixing, decimation filtering,

programmable FIR shaping/bandlimiting filtering,

resampling, Automatic Gain Control (AGC), frequency

discrimination and detection as well as multi-chip

synchronization. The HSP50214B interfaces directly with a

DSP microprocessor to pass baseband and status data.

A top level functional block diagram of the HSP50214B is

shown in Figure 1. The diagram shows the major blocks and

multiplexers used to reconfigure the data path for various

architectures. The HSP50214B can be broken into 13

sections: Synchronization, Input, Input Level Detector,

Carrier Mixer/Numerically Control Oscillator (NCO), CIC

Decimating Filter, Halfband Decimating Filter, 255-Tap

Programmable FIR Filter, Automatic Gain Control (AGC),

Re-sampler/Halfband Filter, Timing NCO, Cartesian to Polar

Converter, Discriminator, and Output Sections. All of these

sections are configured through a microprocessor interface.

The HSP50214B has three clock inputs; two are required and

one is optional. The input level detector, carrier NCO, and CIC

decimating filter sections operate on the rising edge of the

input clock, CLKIN. The halfband filter, programmable FIR

filter, AGC, Re-Sampler/Halfband filters, timing NCO,

discriminator, and output sections operate on the rising edge

of PROCCLK. The third clock, REFCLK, is used to generate

timing error information.

NOTE: All of the clocks may be asynchronous.

PDC Applications Overview

This section highlights the motivation behind the key

programmable features from a communications system level

perspective. These motivations will be defined in terms of ability

to provide DSP processing capability for specific modulation

formats and communication applications. The versatility of the

Programmable Downconverter can be intimidating because of

the many Control Words required for chip configuration. This

section provides system level insight to help allay reservations

about this versatile DSP product. It should help the designer

capitalize on the greatest feature of the PDC - VERSATILITY

THROUGH PROGRAMMABILITY

. It is this feature, when fully

understood, that brings the greatest return on design

investment by offering a single receiver design that can process

the many waveforms required in the communications

marketplace.

FDM Based Standards and Applications

Table 1 provides an overview of some common frequency

division multiplex (FDM) base station applications to which the

PDC can be applied. The PDC provides excellent selectivity

for frequency division multiple access (FDMA) signals. This

high selectivity is achieved with 0.012Hz resolution frequency

control of the NCO and the sharp filter responses capable with

a 255-tap, 22-bit coefficient FIR filter. The 16-bit resolution out

of the Cartesian to Polar Coordinate Converter are routed to

the frequency detector, which is followed by a 63-tap, 22-bit

coefficient FIR filter structure for facilitating FM and FSK

detection. The 14-bit input resolution is the smallest bit

resolution found throughout the conversion and filtering

sections, providing excellent dynamic range in the DSP

processing. A unique input gain scaler adds an additional

42dB of range to the input level variation, to compensate for

changes in the analog RF front end receive equipment.

Synchronization circuitry allows precise timing control of the

base station reconfiguration for all receive channels

simultaneously. Portions of this table were corroborated with

reference [2].

TDM Based Standards and Applications

Table 2 provides an overview of some common Time Division

Multiplexed (TDM) base station applications to which the PDC

can be applied. For time division multiple access (TDMA)

applications, such as North American TDMA (IS136), where

30kHz is the received band of interest for the PCS

basestation, the PDC offers 0.012Hz frequency resolution in

downconversion in addition to

 = 0.35 matched

(programmable) filtering capability. The

/4 DPSK modulation

can be processed using the PDC Cartesian to Polar

coordinate converter and d

/dt detector circuitry or by

processing the I/Q samples in the DSP

P. The PDC provides

TABLE 1. CELLULAR PHONE BASE STATION

APPLICATIONS USING FDMA

STANDARD

AMPS

(IS-91)

MCS-L1

MCS-L2

NMT-400

NMT-900

C450

ETACS

NTACS

RX BAND

(MHz)

824-849 925-940

453-458

890-915

451-456 871-904

915-925

CHANNEL

BW (kHz)

25.0

12.5

20.0

10.0

25.0

12.5

# TRAFFIC

CHANNELS

832

600

1200

200

1999

222

444

1240

800

VOICE

MODULA-

TION

PEAK

DEVIATION

(kHz)

9.5

CONTROL

MODULA-

TION

FSK

PEAK

DEVIATION

(kHz)

4.5

3.5

2.5

6.4

CONTROL

CHANNEL

RATE

(Kbps)

0.3

1.2

5.3

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