DAC5687-EP_15 Datasheet, PDF (22/76 Pages) Texas Instruments – 16-BIT 500-MSPS 2´–8´ INTERPOLATING DUAL-CHANNEL DIGITAL-TO-ANALOG CONVERTER (DAC)

DAC5687-EP
SGLS333 – JUNE 2006
Test Methodology (continued)
10⁰
www.ti.com
10^−2
10^−4
2 Carriers
1 Carrier
4 Carriers
10^−6
3
5
7
9
11
13
Peak-to-Average Ratio − dB
15
G041
Figure 29. WCDMA TM1 Cumulative Complementary Distribution Function for 1, 2, and 4 Carriers
DETAILED DESCRIPTION
Modes of Operation
The DAC5687 has six digital signal processing blocks: FIR1 and FIR2 (interpolate by two digital filters), FMIX
(fine frequency mixer), QMC (quadrature modulation phase correction), FIR3 (interpolate by two digital filter) and
CMIX (coarse frequency mixer). The modes of operation, listed in Table 1, enable or bypass the blocks to
produce different results. The modes are selected by registers CONFIG1, CONFIG2, and CONFIG3 (0x02,
0x03, and 0x04). Block diagrams for each mode (x2, x4, x4L, and x8) are shown in Figure 30 through Figure 33.
MODE
FULL BYPASS
X2
X2 FMIX
X2 QMC
X2 FMIX QMC
X2 CMIX
X2 FMIX CMIX
X2 QMC CMIX
X2 FMIX QMC CMIX
X4
X4 FMIX⁽²⁾
X4 QMC⁽²⁾
X4 FMIX QMC
X4 CMIX
X4L
Table 1. DAC5687 Modes of Operation
FIR1
–
–
–
–
–
–
–
–
–
ON
ON
ON
ON
ON
ON
FIR2
–
–
–
–
–
–
–
–
–
ON
ON
ON
ON
ON
–
FMIX
–
–
ON
–
ON
–
ON
–
ON
–
ON
–
ON
–
–
QMC
–
–
–
ON
ON
–
–
ON ⁽¹⁾
ON ⁽¹⁾
–
–
ON
ON
–
–
FIR3
–
ON
ON
ON
ON
ON
ON
ON
ON
–
–
–
–
–
ON
CMIX
–
–
–
–
–
ON
ON
ON
ON
–
–
–
–
ON
–
(1) The QMC phase correction will be eliminated by the CMIX, so the QMC phase should be set to zero.
The QMC gain settings can still be used to adjust the signal path gain as needed.
(2) f_DAC limited to maximum clock rate for the NCO and QMC, (See the AC specs).
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