参数资料
型号: DAC5687IPZP
厂商: TEXAS INSTRUMENTS INC
元件分类: DAC
英文描述: PARALLEL, WORD INPUT LOADING, 0.0104 us SETTLING TIME, 16-BIT DAC, PQFP100
封装: GREEN, PLASTIC, HTQFP-100
文件页数: 30/79页
文件大小: 2490K
代理商: DAC5687IPZP
www.ti.com
Dual-Channel Real Upconversion
Limitations on Signal BW and Final Output Frequency in X4L and X8 Modes
Fine Mixer (FMIX)
Frequency
Register
32
Accumulator
32
RESET
CLK
PHSTR
32
Phase
Register
16
Look-Up
Table
sin
cos
Σ
16
fNCO_CLK
B0026-02
SLWS164E – FEBRUARY 2005 – REVISED SEPTEMBER 2006
The DAC5687 can be used in a dual-channel mode with real upconversion by mixing with a 1, –1, … sequence
in the signal chain to invert the spectrum. This mixing mode maintains isolation of the A and B channels. There
are two points of mixing: in X4L mode, the FIR1 output is inverted (high-pass mode) by setting registers hpla and
hplb to 1, and the FIR3 output is inverted by setting CMIX to fDAC/2. In X8 mode, the output of FIR1 is inverted
by setting hpla and hplb to 1, and the FIR3 output is inverted by setting CMIX to fDAC/2. In X2 and X4 modes,
the output of FIR3 is inverted by setting CMIX to fDAC/2.
The wide bandwidth of FIR3 (40% passband) in X4L mode provides options for setting four different frequency
ranges, listed in Table 9. For example, with fDATA = 125 MSPS (fDAC = 500 MSPS), setting FIR1/FIR3 to High
Pass/High Pass, respectively, upconverts a signal between 25 MHz and 50 MHz to a signal between 150 MHz
and 175 MHz. With the High Pass/Low Pass and Low Pass/High Pass settings, the upconvertered signal is
spectrally inverted.
Table 9. X4L Mode High-Pass/Low-Pass Options
FIR1
FIR3
Input Frequency
Output Frequency
Bandwidth
Inverted?
Low pass
0–0.4
× f
DATA
0–0.4
× f
DATA
0.4
× f
DATA
No
High pass
Low pass
0.2 to 0.4
× f
DATA
0.6–0.8
× f
DATA
0.2
× f
DATA
Yes
High pass
0.2 to 0.4
× f
DATA
1.2–1.4
× f
DATA
0.2
× f
DATA
No
Low pass
High pass
0–0.4
× f
DATA
1.6–2
× f
DATA
0.4
× f
DATA
Yes
For very wide-bandwidth signals, the FIR3 pass band (0–0.4
× f
DAC/2) can limit the range of the final output
frequency. For example, in X4L FMIX CMIX mode (4
× interpolation with FMIX after FIR1), at the maximum input
data rate of fIN = 125 MSPS, the input signal can be ±50 MHz before running into the transition band of FIR1.
After 2
× interpolation, FIR3 limits the signal to ±100 MHz (0.4 × 250 MHz). Therefore, at the maximum signal
bandwidth, FMIX can mix up to 50 MHz and still fall within the pass band of FIR3. This results in gaps in the final
output frequency between FMIX alone (0 MHz to 50 MHz) and FMIX + CMIX with fDAC/4 (75 MHz to 175 MHz)
and FMIX + CMIX with fDAC/2 (200 MHz to 250 MHz).
In practice, it may be possible to extend the signal into the FIR3 transition band. Referring to Figure 36 in the
preceding FIR Filters section, if 0.5 dB of attenuation at the edge of the signal can be tolerated, then the signal
can be extended up to 0.44
× f
IN. This would extend the range of FMIX in the example to 60 MHz.
The fine mixer block FMIX uses a numerically controlled oscillator (NCO) with a 32-bit frequency register
freq(31:0) and a 16-bit phase register phase(15:0) to provide sin and cos for mixing. The NCO tuning frequency
is programmed in registers 0x09 through 0x0C. Phase offset is programmed in registers 0x0D and 0x0E. A block
diagram of the NCO is shown in Figure 39.
Figure 39. Block Diagram of the NCO
36
Copyright 2005–2006, Texas Instruments Incorporated
Product Folder Link(s): DAC5687
相关PDF资料
PDF描述
DAC5687IPZPG4 PARALLEL, WORD INPUT LOADING, 0.0104 us SETTLING TIME, 16-BIT DAC, PQFP100
DAC5688IRGCTG4 PARALLEL, WORD INPUT LOADING, 0.0104 us SETTLING TIME, 16-BIT DAC, PQCC64
DAC702LH PARALLEL, WORD INPUT LOADING, 4 us SETTLING TIME, 16-BIT DAC, CDIP24
DAC7545KUG4 PARALLEL, WORD INPUT LOADING, 2 us SETTLING TIME, 12-BIT DAC, PDSO20
DAC7545JP PARALLEL, WORD INPUT LOADING, 2 us SETTLING TIME, 12-BIT DAC, PDIP20
相关代理商/技术参数
参数描述
DAC5687IPZPG4 功能描述:数模转换器- DAC 16-bit 500 MSPS 2-8x Interpolat’g Dual-Ch RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube
DAC5687IPZPR 功能描述:数模转换器- DAC 16-bit 500 MSPS 2-8x Interpolat’g Dual-Ch RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube
DAC5687IPZPRG4 功能描述:数模转换器- DAC 16-bit 500 MSPS 2-8x Interpolat’g Dual-Ch RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube
DAC5687MPZPEP 功能描述:数模转换器- DAC 16B 500Msps 2X-8X Interp 2-Channel DAC RoHS:否 制造商:Texas Instruments 转换器数量:1 DAC 输出端数量:1 转换速率:2 MSPs 分辨率:16 bit 接口类型:QSPI, SPI, Serial (3-Wire, Microwire) 稳定时间:1 us 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-14 封装:Tube
DAC5688 制造商:TI 制造商全称:Texas Instruments 功能描述:DUAL-CHANNEL, 16-BIT, 800 MSPS, 2x-8x INTERPOLATING DIGITAL-TO-ANALOG CONVERTER (DAC)