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Honored Contributor I

About THDB-ADA and other AD/DA Daughter cards

Hello all, 


According to the user's guide of thdb-ada (ad/da converter) (, DC signals and low-frequency AC signals are not supported for AD or DA conversion operations. Since I need an AD/DA daughter card covering the frequency spectrum of (5 Hz - 100 kHz), I wonder what is the minimum supported frequency of THDB-ADA daughter board? 


In addition, after some research, I found another AD/DA card: p0035 - [dcc] ad/da data conversion card ( and I couldn't see any restriction on the type or the frequency of the signal (AC or DC) in its user's manual ( Do you guys know this daughter board support DC signals? 



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2 Replies
Honored Contributor I

Hi there,  


I checked the datasheet briefly and I couldn't find the exact minimum supported frequency mentioned, though I might have missed. Nevertheless, I believe the number would still be in MHz range.  


Both THDB-ADA (AD/DA converter) and P0035 - [DCC] AD/DA Data Conversion Card support AC signal only. They adopt the same output configuration with differential coupling using transformer.  


We have some FPGA boards which support DC signals, but they are still in KHz range. You might want to look at some Arduino daughter cards for Hz range. What is your mainboard at the moment ? 


Dav from Terasic
Honored Contributor I

Hi Dav, 


Thanks for your response. 


Actually, I want to sample analog signals with the frequency of 5 Hz and up to 100 kiloHz. Moreover, in my case, the analog signal consists of the pulses with ultrashort pulse durations (e.g. ~ 30-40 ns). For this reason, I need an high speed AD/DA daughtercard (or a FPGA board with built-in AD/DA operation) to sample each pulse properly. Therefore, AD/DA cards with very high sampling rates are required and I believe that Arduino based solutions would be insufficient. 


I was thinking to use THDB-ADA with Cyclone III FPGA Starter Kit (or similar FPGA development boards in the same price range). 


In addition, after some research, I found another FPGA development kit: ADC-SoC (


It has a built-in ADC option up to 150 MSPS. However, I have checked the User's Manual and couldn't find any information about the DC signal support. 


By the way, I am open to alternative design configurations to sample such an analog signal with ultra narrow nanosecond pulses.