GC5016 datasheet(33/88 Pages) TI

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GC5016

SLWS142G − JANUARY 2003 − REVISED NOVEMBER 2005

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14 GC5016 DIGITAL UP CONVERSION (DUC) MODE

The GC5016 can be configured as a digital up converter (DUC). The DUC interpolates, filters, mixes, and sums the

customer inputs into one or several output ports. The GC5016 DUC (See Figures 2 and 16) has several blocks:

Transmit Input Interface

Gain

PFIR

CIC

Mixer

Sum, SumIn, and Transmit Output Formatter

The GC5016 has either four independent DUC channels, or two Wideband (split IQ) DUC channels. The DUC

accepts real or complex inputs, with complex being the more common. The GC5016 can have one, two, or four real

or complex DUC outputs.

The up-conversion channel details are reproduced in Figure 16.

NCO

Frequency

Phase

6 Stage

CIC Filter

Interp. by 1

*256

127 to 255 Tap

PFIR

Interp. by 4

*16

Gain

Figure 16. Up-Conversion Channel Detail

The Transmit input formatter generates the Frame Strobe and channel divided clock, and is used to receive the

customer IQ data. The data input can be parallel IQ, interleaved IQ, or Time Division Multiplexed (TDM) IQ. The

Frame Strobe signal is generated to indicate to customer logic that another input sample is required.

The gain block provides fine gain adjustment for the channel’s IQ data.

The PFIR provides the first stage of interpolation. The typical PFIR interpolation is 3, 4, or 5. The number of PFIR

taps is dependent on the number of data streams and number of clocks available to compute the FIR taps. The PFIR

can interpolate from 1 to 16.

The Cascade Integrator Comb (CIC)filter provides the second stage of interpolation. The 6 stage CIC M=1 filter can

interpolate from 1 to 256.

The interpolated IQ data and the NCO’s frequency output sinusoid are mixed together in the mixer to generate the

channel digital IF output. The mixer output can be real or complex.

The Sum block within the GC5016 can be used to combine other GC5016 outputs (using the SumIn path) with this

GC5016’s channels.

The Transmit Output Format logic converts the Sum or fixed scale data to the Real, Interleaved Complex, Parallel

Complex, Double Rate Real, or Double Rate Complex output modes. An IFLG signal is output.

14.1 Special Modes− Split IQ, and Double Rate DUC Output

There are two special DUC modes: SplitIQ, and double rate.

The splitIQ Mode combines two channels to provide for more PFIR filtering. The A and B, or C and D channels can

be used in the splitIQ mode. The A and C channels process the I data, and the B and D channels process the Q data.

The parallel IQ and TDM modes may be used with the splitiq mode. In the splitIQ mode, the channel A and C mixers

are used. The cmd5016 software keywords splitiQ, splitIQ_AB, and splitIQ_CD are used to control this function.

GC5016 Datasheet(PDF) 33 Page - Texas Instruments

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