GC5316 Datasheet, PDF (4/75 Pages) Texas Instruments – HIGH-DENSITY DIGITAL DOWNCONVERTER AND UPCONVERTER

GC5316
SLWS154A − JANUARY 2004 − REVISED MARCH 2004
2.1 Receive Input Interface
Bypass
16
rxin_a
Test & Noise 16
G e ne ra tor
FIFO
16
rxin_b
Test & Noise
G e ne ra tor
Bypass
FIFO
www.ti.com
Upper 16 of 18
Q
18
R esam pler
Block
I
18
S e le ct
bus 0
Upper 16 of 18
18
18
S e le c t
bus 1
Bypass
16
rxin_c
Test & Noise 16
G e ne ra tor
FIFO
Upper 16 of 18
R esam pler
Block
Q ¹⁸
I
18
S e le c t
bus 2
Bypass
16
rxin_d
Test & N oise ¹⁶
G e ne ra tor
FIFO
Upper 16 of 18
18
18
S e le c t
bus 3
Select
resampler_ena
Special 92.16 MSPS input rate
mode
Figure 2. Receive Input Interface
The four ports support four independent real input signals or two complex. Complex signal data is input with I data
driving one input port and Q data driving another. This means that there are only two signal data ports available when
in complex input mode. The mapping of I and Q data onto the four input ports is programmable.
2.1.1 Test and Noise Generator and FIFO
Incoming data first enters the test and noise generator block. This block can either pass the data through, replace
the input data with a pattern generated internally (useful in test), or can add noise to the input at a user programmable
level.
Most applications pass data through this block unchanged by clearing slf_tst_ena, rduz_sens_ena, and tst_on.
Test sequences are useful for board bring-up or for power-on self-test. Board bring-up and self-test procedures and
configuration files are available on the web. Self-test will be described in greater detail in a later section. Suffice to
say here that the receive data input is replaced by pseudo-random patterns at this point in the processing chain.
A few applications that require receiver desensitization which is done by adding digital noise to the input. The same
pseudo-random sequence generator is used as a noise source. Nz_pwr_mask is used to select which input data bits
get noise added to them. In this way the user has control over the noise power introduced in receiver desensitization.
4