 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
AD9767 Datasheet(PDF) 11 Page - Analog Devices |
|
||||||||||||||||||||||||||||||
AD9767 Datasheet(HTML) 11 Page - Analog Devices |
|
|
11 / 27 page  REV. B AD9767 –11– Performing a differential-to-single-ended conversion via a trans- former also provides the ability to deliver twice the reconstructed signal power to the load (i.e., assuming no source termination). Since the output currents of IOUTA and IOUTB are complemen- tary, they become additive when processed differentially. A properly selected transformer will allow the AD9767 to provide the required power and voltage levels to different loads. The output impedance of IOUTA and IOUTB is determined by the equivalent parallel combination of the PMOS switches associ- ated with the current sources and is typically 100 k Ω in parallel with 5 pF. It is also slightly dependent on the output voltage (i.e., VOUTA and VOUTB) due to the nature of a PMOS device. As a result, maintaining IOUTA and/or IOUTB at a virtual ground via an I-V op amp configuration will result in the optimum dc linearity. Note the INL/DNL specifications for the AD9767 are measured with IOUTA maintained at a virtual ground via an op amp. IOUTA and IOUTB also have a negative and positive voltage com- pliance range that must be adhered to in order to achieve opti- mum performance. The negative output compliance range of –1.0 V is set by the breakdown limits of the CMOS process. Operation beyond this maximum limit may result in a break- down of the output stage and affect the reliability of the AD9767. The positive output compliance range is slightly dependent on the full-scale output current, IOUTFS. It degrades slightly from its nominal 1.25 V for an IOUTFS = 20 mA to 1.00 V for an IOUTFS = 2 mA. The optimum distortion performance for a single-ended or differential output is achieved when the maxi- mum full-scale signal at IOUTA and IOUTB does not exceed 0.5 V. Applications requiring the AD9767’s output (i.e., VOUTA and/or VOUTB) to extend its output compliance range should size RLOAD accordingly. Operation beyond this compliance range will ad- versely affect the AD9767’s linearity performance and subse- quently degrade its distortion performance. DIGITAL INPUTS The AD9767’s digital inputs consist of two channels. For the dual port mode, each DAC has its own dedicated 14-bit data port, WRT line and CLK line. In the interleaved timing mode, the function of the digital control pins changes as described in the Interleaved Mode Timing section. The 14-bit parallel data inputs follow straight binary coding where DB13 is the Most Significant Bit (MSB) and DB0 is the Least Significant Bit (LSB). IOUTA produces a full-scale output current when all data bits are at Logic 1. IOUTB produces a complementary output with the full-scale current split between the two outputs as a function of the input code. The digital interface is implemented using an edge-triggered master slave latch. The DAC outputs are updated following either the rising edge, or every other rising edge of the clock, depending on whether dual or interleaved mode is being used. The DAC outputs are designed to support a clock rate as high as 125 MSPS. The clock can be operated at any duty cycle that meets the specified latch pulsewidth. The setup and hold times can also be varied within the clock cycle as long as the specified minimum times are met, although the location of these transi- tion edges may affect digital feedthrough and distortion perfor- mance. Best performance is typically achieved when the input data transitions on the falling edge of a 50% duty cycle clock. DAC TIMING The AD9767 can operate in two timing modes, dual and inter- leaved, which are described below. The block diagram in Figure 25 represents the latch architecture in the interleaved timing mode. DUAL PORT MODE TIMING For the following section, refer to Figure 2. When the mode pin is at Logic 1, the AD9767 operates in dual port mode. The AD9767 functions as two distinct DACs. Each DAC has its own completely independent digital input and control lines. The AD9767 features a double buffered data path. Data enters the device through the channel input latches. This data is then transferred to the DAC latch in each signal path. Once the data is loaded into the DAC latch, the analog output will settle to its new value. For general consideration, the WRT lines control the channel input latches and the CLK lines control the DAC latches. Both sets of latches are updated on the rising edge of their respective control signals. The rising edge of CLK should occur before or simultaneously with the rising edge of WRT. Should the rising edge of CLK occur after the rising edge of WRT, a 2 ns minimum delay should be maintained from the rising edge of WRT to the rising edge of CLK. Timing specifications for dual port mode are given in Figures 23 and 24. WRT1/WRT2 CLK1/CLK2 DATA IN IOUTA OR IOUTB tLPW tPD tS tH tCPW Figure 23. Dual Mode Timing D1 D2 D3 D4 D5 DATA IN WRT1/WRT2 CLK1/CLK2 xx D1 D2 D3 D4 IOUTA OR IOUTB Figure 24. Dual Mode Timing |
Similar Part No. - AD9767 |
|
Similar Description - AD9767 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
