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Altera_Forum's avatar
Altera_Forum
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15 years ago

Gain control using fpga

Hi, i have four FIR filters and i want to control the gain in the output of each filter and then sum their outputs. The result is sended to an DAC. it is possible to control the gain in fpga...
Altera_Forum's avatar
Altera_Forum
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15 years ago

Taking the 1 dB gain step simply as a specification, you'll need a table of gain factors and a multiplier to implement it.

According to the HSMC data conversion board schematic, the output level will be lower than +10 dBm due to the internal termination. In impedance matched setting (R120/122 populated), + 4dBm in 50 ohm should be achieved, with R121/R123 populated only + 2 dBm due to impedance mismatch.

So there will be probably a problem to achieve the specified output without an amplifier.