max5885egmtd Maxim Integrated Products, Inc., max5885egmtd Datasheet - Page 12

• Manufacturer Part Number: max5885egmtd
• Description: Max5885 3.3v, 16-bit, 200msps High Dynamic Performance Dac With Cmos Inputs
• Manufacturer: Maxim Integrated Products, Inc.

A dominant specification is ACLR, a parameter which
reflects the ratio of the power in the desired carrier
band to the power in an adjacent carrier band. The
specification covers the first two adjacent bands, and is
measured on both sides of the desired carrier.
According to the transmit mask for CDMA and W-CDMA
architectures, the power ratio of the integrated carrier
channel energy to the integrated adjacent channel
energy must be >45dB for the first adjacent carrier slot
(ACLR 1) and >50dB for the second adjacent carrier
slot (ACLR 2). This specification applies to the output of
the entire transmitter signal chain. The requirement for
only the DAC block of the transmitter must be tighter,
with a typical margin of >15dB, requiring the DAC’s
ACLR 1 to be better than 60dB.
3.3V, 16-Bit, 200Msps High Dynamic
Performance DAC with CMOS Inputs
Figure 6. Differential to Single-Ended Conversion Using a Wideband RF Transformer
Figure 7. MAX5885 Differential Output Configuration
12
*Note that due to their own IM effects and noise limitations, spectrum analyzers introduce ACLR errors, which can falsify the measure-
ment. For a single-carrier ACLR measurement greater than 70dB, these measurement limitations are significant, becoming even more
restricting for multicarrier measurement. Before attempting an ACLR measurement, it is recommended consulting application notes pro-
vided by major spectrum analyzer manufacturers that provide useful tips on how to use their instruments for such tests.
16
B0–B15
______________________________________________________________________________________
AGND
AV
DD
MAX5885
DGND
DV
DD
16
CLKGND
B0–B15
VCLK
AGND
AV
IOUTP
IOUTN
DD
MAX5885
DGND
DV
50Ω
100Ω
50Ω
DD
CLKGND
VCLK
OUTP
OUTN
IOUTN
IOUTP
50Ω
100Ω
50Ω
Adjacent channel leakage is caused by a single
spread-spectrum carrier, which generates intermodula-
tion (IM) products between the frequency components
located within the carrier band. The energy at one end
of the carrier band generates IM products with the
energy from the opposite end of the carrier band. For
single-carrier W-CDMA modulation, these IMD products
are spread 3.84MHz over the adjacent sideband. Four
contiguous W-CDMA carriers spread their IM products
over a bandwidth of 20MHz on either side of the 20MHz
total carrier bandwidth. In this four-carrier scenario,
only the energy in the first adjacent 3.84MHz sideband
is considered for ACLR 1. To measure ACLR, drive the
converter with a W-CDMA pattern. Make sure that the
signal is backed off by the peak-to-average ratio, such
that the DAC is not clipping the signal. ACLR can then
be measured with the ACLR measurement function built
into your spectrum analyzer.
Figure 8 shows the ACLR performance for a single
W-CDMA carrier (f
applied to the MAX5885 (including measurement system
limitations*).
Figure 9 illustrates the ACLR test results for the
MAX5885 with a four-carrier W-CDMA signal at an out-
put frequency of 30.72MHz and a sampling frequency
of 184.32MHz. Considerable care must be taken to
ensure accurate measurement of this parameter.
T1, 1:1
T2, 1:1
PERFORMS THE DIFFERENTIAL TO
WIDEBAND RF TRANSFORMER T2
SINGLE-ENDED CONVERSION.
CLK
V
OUT
= 184.32MHz, f
, SINGLE ENDED
OUT
= 30.72MHz)