# help for the choice of the DA！！

Hello，I'm finding a DA satifing the follow factors:

a) can garantee the width of signal is 500ns~20us，and the repetition rate  of 10K~50KHz

b) can garantee the amplitude of the signal is 0V~4V

Parents
• Hi ,

What do you mean by "width of the signal"?

Do you have any other requirements such as digital interface (SPI vs i2c) and channel counts?

Cheers,

Ivan

• Hi,thank you for your reply! The "width of the signal" is the modulation signal that I want the DA to output. The signal  consists different amplitude square signals,and  likes modulation of the sine signal  and square signal.

I need 8 channels of  the modulation signals, and the delay time of the any two-way signals of 6 channels  should not exceed 20ns.  Now I'm finding the method to acheive it.

Can you help me to acheive it and offer the reference plan of it ?

Thank you!!

• Hi,

Sorry I was not able to comprehend what you want to do. Can you provide a block diagram and the signal you want to create together with the 500nS-20uS and 20nS requirement you mentioned, please?

Cheers,

Ivan

• 信号是实际一系列幅值不同的脉冲信号组成，包络看起来像正弦波，脉冲的宽度在500nS-20uS 之间，重频在1-10KHz之间可控，总共需要8路这样的信号，其中6路要求同步（任意两路之间的延迟时间不超过20ns）

• The signal is composed of a series of actual pulse signals with different amplitudes. The envelope looks like a sinusoidal wave. The width of the pulse is between 500nS-20uS and the repetition frequency is controllable between 1 and 10KHz. A total of 8 such signals are required. Six of them require synchronization (the delay time between any two channels is no more than 20ns).

• Hi,

Can you provide a picture of the waveform please?

You may also want to post your question in EZ for Chinese customers.

Cheers,

Ivan

• Hi,

Do you really intend to create pulses going from 2V to a certain value, then back to 2V?

What is the application of this circuit?

You may consider using AD5676R which has 8 channels and can output 0 to 5V using a gain of 2.

However, the fastest update period is around 870nS, and on top of that, you should also consider the slew rate for big voltage steps.

Cheers,
Ivan

• Hi,

Thank you for your reply. First, I'm very sure I need to creat pulses going from 2V to a certain value, then back to 2V. Second, the fastest update period of AD5676R is around 870nS and I think it doesn't satisfy 500ns's  width of the  pulse .

If I use AD9784 and a amplifier,what do you think? Can you help me choose a amplifier?

• Hi,

If you are welcome to the idea of using multiple DACs, then you can check AD5449, which is a 2-Channel Multiplying DAC capable of 2.47 MSPS update rate, which is around 405 nS between each frame sent.

You will also be needing a transimpedance amplifier at the outputs.

If you still need higher update rates, you may check High-Speed DAC community here in EZ.

Cheers,

Ivan

• Can you give me some suggestions?? I'm going to use AD9748 and ad8048 to complete the design,but Iam not sure about it .And to fullfill the 4v  amplitude ,I need to use ad8048 to get the gain of about 10. Iam not sure.

• Hi,

AD9748 is a high-speed DAC, can you kindly post your question in this community :

https://ez.analog.com/data_converters/high-speed_dacs/

Cheers,

Ivan