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Altera_Forum's avatar
Altera_Forum
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14 years ago

system design using cyclone II

Hi, I am trying to implement a hardware system which uses current to compute distances. The incoming current is obtained from a sensor, and will be sampled and input into my FPGA. The ADC is 14...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Thx for the reply. I will try to make it clearer since I am new to hardware design...

The current is obtained from a position detection sensor(PSD) which transfers light into current in order to calculate the position where the light is located on the sensor. After analog processing(which is completed by another colleague), our interested signal frequency is 154Khz. Usually there are signals from other frequency bands so the noise is extremely large. That's why I wanna use a lock-in amplifier.

The lock-in amplifier consists of a PLL, a mixer and a LPF. The PLL is to generate a reference signal which also is 154Khz. The locked signal and the referenced signal will be sent to the mixer and the LPF will keep the DC component of the output, which is proportional to the amplitude of the original signal of interested.

The lock-in amplifier will be implemented in FPGA. There will be other DSP processing in FPGA using DSP kit, but I'm not there yet.:p

About the ADC, at first I was thinking of using the Virtex 6 with AD/DA, that's where I got the information. like I said I was new to hardware design so I really don't know much about the AD/DA selection...thanks for the information.