DS3922

PDSPP1DS6P51165515AA

Stand Alone FFT Processor

Advance Information

Issue 2.0

April 1999

Features

q Completely self contained FFT Processor

q Pin and functionally compatible with the

PDSP16510A

q Expanded width internal RAM supports up to 1024

complex points

q 18 bit internal data bus with block floating point

arithmetic for increased dynamic range

q 500 MIP operation gives 87 microsecond

transformation times for 1024 points

q Up to 45MHz sampling rates with multiple devices.

q Up to 85dB noise rejection

q A choice of internal window operators with no

external ROM provide up to 67dB side lobe

attenuation.

q 84 pin PGA or 132 pin surface mount package

Associated Products

PDSP16330 Pythagoras Processor.

PDSP16256 Programmable FIR Filter.

PDSP16350 I/Q Splitter / NCO

PDSP16510A Stand Alone FFT Processor

The PDSP16515A performs Forward or Inverse Fast

Fourier Transforms on complex or real data sets

containing up to 1024 points. Data and coefficient input

are both represented by 16 bits. Data is expanded

internally to 18 bits and subject to Block Floating Point

arithmetic to preserve a greater dynamic range.

An internal RAM is provided which can hold up to 1024

complex data points. This removes the memory transfer

bottleneck, inherent in building block solutions. Its

organisation allows the PDSP16515A to

simultaneously input new data, transform data stored in

the RAM, and to output previous results. No external

buffering is needed for transforms containing up to 256

points, and the PDSP16515A can be directly connected

to an A/D converter to perform continuous transforms.

The user can choose to overlap data blocks by either

0%, 50%, or 75%. Inputs and outputs are synchronous

to the 45MHz system clock used for internal operations.

Ordering Information

PDSP16515A C0 AC

( Commercial - PGA

Package )

PDSP16515A C0 GC

( Commercial - Leaded

Chip Carrier )

PDSP16515A B0 AC

( Industrial - PGA

Package )

PDSP16515A B0 GC

( Industrial - Leaded

Chip Carrier )

PDSP16515A A0 AC

( Military - PGA

Package )

PDSP16515A A0 GC

( Military - Leaded Chip

Carrier )

PDSP16515A/MA/GCPR ( Military - Screened

Leaded Chip Carrier. See separate datasheet for

details )

A 1024 point complex transform can be completed in

some 87ยตs, which is equivalent to throughput rates of

500 million operations per second. Multiple devices can

be connected in parallel in order to increase the

sampling rate up to the 45MHz system clock. Six

devices are needed to give the maximum performance

with 1024 point transforms.

Either a Hamming or a Blackman-Harris window

operator can be internally applied to the incoming real or

complex data. The latter gives 67dB side lobe

attenuation. The operator values are calculated

internally and do not require an external ROM nor do

they incur any time penalty.

The increased internal bus size together with block

floating arithmetic produce up to 85dB of noise

rejection.

The device outputs the real and imaginary components

of the frequency bins. These can be directly connected

to the PDSP16330 in order to produce magnitude and

phase values from the complex data.

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