AD6636PCB datasheet(38/72 Pages) AD

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AD6636

Rev. 0 | Page 38 of 72

The interleaving function is a simple time-multiplexing

function, with lower data rate on the input side and higher data

rate on the output side. The output data rate is the sum of all

input stream data rates that are combined.

The channels that need to be combined are programmable with

sufficient flexibility. Table 22 gives the combinations that are

possible using a 4-bit word (stream control bits) in the Parallel

Port Control 2 register.

After interleaving of data (see the Output Data Router section),

the data is passed to the second subblock, in which either

complex filter completion or biphase filtering can be

performed.

Complex Filter Completion

In normal operation, each individual channel’s filter performs

real coefficient, complex data filtering.

Two channels are used to perform complex coefficient data

filtering. One channel is loaded with the real part (in-phase) of

the coefficients; the other channel is loaded with the imaginary

part (quadrature) of the coefficients.

The terms calculated are as follows:

• (ICi, QCi) from first channel

• (Icq, QCq) from the second channel

Using these terms, the complex filter is completed by applying

the following formula:

(I + jQ) (Ci + jCq) = (ICi − QCq) + j(ICq + QCi)

The channels to be combined can be programmed using a 3-bit

complex control word in the Parallel Output Control 2 register.

The values for the 3-bit control word and the corresponding

settings are listed in Table 23.

These outputs go to the six available AGCs. Not all AGCs need

to be used in the different applications, so unused AGCs can be

bypassed and the output data streams ignored by the parallel

output ports. For example, if Streams 0 and 1 are combined for a

complex filter, AGC 1 can be bypassed, because Stream 1 is

already combined into Stream 0 and sent to AGC 0.

Table 22. Stream Control Bit Combinations

Stream Control Bits

Output Streams

No. of Streams

0000

Ch 0/1 combined, Ch 2, Ch 3, Ch 4, Ch 5 independent

0001

Ch 0/1/2 combined, Ch 3, Ch 4, Ch5 independent

0010

Ch 0/1/2/3 combined; Ch 4, Ch 5 independent

0011

Ch 0/1/2/3/4 combined; Ch 5 independent

0100

Ch 0/1/2/3/4/5 combined

0101

Ch 0/1/2 combined, Ch 3/4/5 combined

0110

Ch 0/1 combined, Ch 2/3 combined, Ch 4/5 combined

0111

Ch 0/1 combined, Ch 2/3 combined, Ch 4, Ch 5 independent

1000

Ch 0/1/2 combined, Ch 3/4 combined, Ch 5 independent

1001

Ch 0/1/2/3 combined, Ch 4/5 combined.

Any other state

Independent channels

Table 23. Definitions for Complex Control Register Selections

Complex Control Word

Data Routing

Comments

000

No complex filters

Stream control register controls AGC usage.

001

Stream 0/1 combined

Allows Ch 0 and Ch 1 to form a complex filter.

010

Stream 0/1 combined, Stream 2/3

combined

Allows Ch 0 and Ch 1 to form a complex filter and Ch 2 and Ch 3 to

form a complex filter.

011

Stream 0/1 combined, Stream 2/3

combined, Stream 4/5 combined

Allows Ch 0 and Ch 1 to form a complex filter, Ch 2 and Ch 3 to form a

complex filte,r and Ch 4 and Ch 5 to form a complex filter.

101

Stream 0/1 Combined

Allows Ch 0 and Ch 1 to form a biphase filter.

110

Stream 0/1 combined, Stream 2/3

combined

Allows Ch 0 and Ch 1 to form a biphase filter, and Ch 2 and Ch 3 to

form a biphase filter.

111

Stream 0/1 combined, Stream 2/3

combined, Stream 4/5 combined

Allows Ch 0 and Ch 1 to form a biphase filter, Ch 2 and Ch 3 to form a

biphase filter, and Ch 4 and Ch 5 to form a biphase filter.

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