AD9773-EB Analog Devices Inc, AD9773-EB Datasheet - Page 33

• Manufacturer Part Number: AD9773-EB
• Description: BOARD EVAL FOR AD9773
• Manufacturer: Analog Devices Inc
• Series: TxDAC®r

Specifications of AD9773-EB

• Rohs Status: RoHS non-compliant
• Number Of Dac's: 2
• Number Of Bits: 12
• Outputs And Type: 2, Differential
• Sampling Rate (per Second): 160M
• Data Interface: Parallel
• Settling Time: 11ns
• Dac Type: Current
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD9773

Under these conditions, IQSEL = 0 latches the data into the I
channel on the clock rising edge, while IQSEL = 1 latches the
data into the Q channel. It is possible to invert the I and Q
selection by setting Control Register 02h, Bit 1 to the invert
state (Logic 1). Figure 56 illustrates the timing requirements for
the data inputs as well as the IQSEL input. Note that the
1× interpolation rate is not available in the one-port mode.
One-port mode is very useful when interfacing with devices
such as the Analog Devices AD6622 or AD6623 transmit signal
processors, in which two digital data channels have been
interleaved (multiplexed).
The programmable modes’ ONEPORTCLK inversion,
ONEPORTCLK driver strength and IQ pairing described in the
PLL Enabled, Two-Port Mode section have identical
functionality with the PLL disabled.
INPUT DATA AT PORT 1
t
t
t
t
t
DIGITAL FILTER MODES
The I and Q data paths of the AD9773 have their own
independent half-band FIR filters. Each data path consists of
three FIR filters, providing up to 8× interpolation for each
channel. The rate of interpolation is determined by the state of
Control Register 01h, Bits 7 and 6. Figure 2 to Figure 4 show the
response of the digital filters when the AD9773 is set to 2×, 4×,
and 8× modes. The frequency axes of these graphs have been
normalized to the input data rate of the DAC. As the graphs
show, the digital filters can provide greater than 75 dB of
out-of-band rejection.
An
AD9773 interpolation filters in the various modes.
OD
S
H
IQS
IQH
I AND Q INTERLEAVED
= 3.0ns (MAX)
= –1.0ns (MAX)
= 4.0ns (MIN)
= 3.5ns (MAX)
= –1.5ns (MAX)
online tool
TO 5.5ns (MAX)
ONEPORTCLK
CLKIN
IQSEL
Figure 56. Timing Requirements in One-Port
is available for quick and easy analysis of the
Input Mode with DLL Disabled
t
IQS
t
OD
t
S
t
H
t
IQH
Rev. D | Page 33 of 60
AMPLITUDE MODULATION
Given two sine waves at the same frequency, but with a 90°
phase difference, a point of view in time can be taken such that
the waveform that leads in phase is cosinusoidal and the
waveform that lags is sinusoidal. Analysis of complex variables
states that the cosine waveform can be defined as having real
positive and negative frequency components, while the sine
waveform consists of imaginary positive and negative frequency
images. This is shown graphically in the frequency domain in
Figure 57.
Amplitude modulating a baseband signal with a sine or a cosine
convolves the baseband signal with the modulating carrier in
the frequency domain. Amplitude scaling of the modulated
signal reduces the positive and negative frequency images by a
factor of 2. This scaling is very important in the discussion of
the various modulation modes. The phase relationship of the
modulated signals is dependent on whether the modulating
carrier is sinusoidal or cosinusoidal, again with respect to the
reference point of the viewer. Examples of sine and cosine
modulation are given in Figure 58.
Ae
Ae
–jωt
–jωt
/2j
/2
Figure 58. Baseband Signal, Amplitude Modulated
e
e
–jωt
Figure 57. Real and Imaginary Components of
–jωt
Sinusoidal and Cosinusoidal Waveforms
/2j
/2
with Sine and Cosine Carriers
DC
DC
DC
DC
Ae
Ae
–jωt
–jωt
e
e
–jωt
–jωt
SINE
COSINE
/2j
/2
/2j
/2
SINUSOIDAL
MODULATION
COSINUSOIDAL
MODULATION
AD9773