參數資料
型號: AD9957BSVZ
廠商: ANALOG DEVICES INC
元件分類: 通信及網絡
英文描述: 1 GSPS Quadrature Digital Upconverter with 18-Bit IQ Data Path and 14-Bit DAC
中文描述: SPECIALTY TELECOM CIRCUIT, PQFP100
封裝: ROHS COMPLIANT, MS-026AED-HD, TQFP-100
文件頁數: 25/60頁
文件大小: 840K
代理商: AD9957BSVZ
AD9957
Rev. 0 | Page 25 of 60
–2.8
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–3.1
0
0.1
0.2
0.4
0.3
0.5
0
(
FREQUENCY RELATIVE TO DAC SAMPLE RATE
COMPENSATED RESPONSE
Figure 38. DAC Response with Inverse Sinc Compensation
OUTPUT SCALE FACTOR (OSF)
In QDUC and interpolating DAC modes, output amplitude is
controlled using an 8-bit digital multiplier. The 8-bit multiplier
value is called the output scale factor (OSF) and is programmed
via the appropriate control registers. It is available for each of
the eight profiles. The LSB weight is 2
7
, which yields a multiplier
range of 0 to 1.9921875 (2 2
7
). The gain extends to nearly a
factor of 2 to provide a means to overcome the intrinsic loss
through the modulator when operating in the quadrature
modulation mode.
In interpolating DAC mode, the OSF should not be programmed
to exceed unity, as clipping can result. Programming the 8-bit
multiplier to unity gain (0x80) bypasses the stage and reduces
power consumption.
14-BIT DAC
The AD9957 incorporates an integrated 14-bit current-output
DAC. The output current is delivered as a balanced signal using
two outputs. The use of balanced outputs reduces the amount of
common-mode noise at the DAC output, increasing signal-to-
noise ratio. An external resistor (R
SET
) connected between the
DAC_RSET pin and AGND establishes a reference current. The
full-scale output current of the DAC (I
OUT
) is a scaled version of
the reference current (see the Auxiliary DAC section that
follows).
Proper attention should be paid to the load termination to keep
the output voltage within the specified compliance range, as
voltages developed beyond this range cause excessive distortion
and can damage the DAC output circuitry.
Auxiliary DAC
The full-scale output current of the main DAC (I
OUT
) is
controlled by an 8-bit auxiliary DAC. An 8-bit code word stored
in the appropriate register map location sets I
OUT
according to
the following equation:
1
=
96
4
86
R
CODE
I
SET
OUT
(6)
where:
R
SET
is the value of the R
SET
resistor (in ohms).
CODE
is the 8-bit value supplied to the auxiliary DAC (default
is 127).
For example, with R
SET
= 10,000 and CODE = 127, I
OUT
=
20.07 mA.
相關PDF資料
PDF描述
AD9957BSVZ-REEL 1 GSPS Quadrature Digital Upconverter with 18-Bit IQ Data Path and 14-Bit DAC
AD9957_07 1 GSPS Quadrature Digital Upconverter with 18-Bit IQ Data Path and 14-Bit DAC
AD9958BCPZ-REEL7 2-Channel 500 MSPS DDS with 10-Bit DACs
AD9958 2-Channel 500 MSPS DDS with 10-Bit DACs
AD9958BCPZ 2-Channel 500 MSPS DDS with 10-Bit DACs
相關代理商/技術參數
參數描述
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