DAC on STRATIX II EP2S60

[mehanathan]

Sir/Madam,

I am using a dac on stratix board to generate a triangular waveform.

Actually the DAC in stratix board is dac904. I have gone through its datasheet.

I hav designed as clock to dac is 100MHz and the input to 14 bit dac is an up/down counter of 10MHz.

But i get only a peak to peak voltage of only 20mV even when all the 14 bits of dac is HIGH when observed in an oscilloscope.

As per the datasheet of dac904, it consists of a current source of 20mA and stratix board uses a 1:1 ratio transformer to interface to a 50 ohm impedance load. so, i should get a maximum of 1V when all bits are HIGH.

Am i right in the way i proceed??
If i am right then why do i get 20mV instead of 1V when all the bits are HIGH??
What could be wrong??

I have attached the signaltap waveform of data input to the dac.

 

[barry]

There is a resistor on pin FSA that determines the output range-look at that. Also, do you have 50 ohm pulldowns on the output pins?

 

[mehanathan]

I am getting analog output from an output SMA Connector (J15) in stratix board.

From development board datasheet it sayys it uses a 1:1 transformer to couple the output to SMA.

 

[FvM]

The transformer coupled output has a lower cut-off frequency of serveral 100 kHz or so. I can't send kHz signals.