automatic control gain

[ashley0927]

HI all,



I am currently doing a DDS function generator which will generate 20 Vpp sine wave within 0-40 MHz.As frequency higher,the amplitude from DDS module become lower which are when frequency is 1MHz, amplitude= 1.25V and when f=40Mhz,amplitude=250mV which are quite low, that why I need to design a amplifier which can maintain the amplitude of the signal in 20Vpp for all frequency (0-40MHz)

The first solution come in my mind is to use https://www.ti.com/product/tl026 this product, but I am not sure it will work or not,so any suggestion on how to design the circuit??



Thanks

 

[crutschow]

That device has a worst-case maximum output voltage of 3Vpp.

20Vpp is a rather large signal level for such a high frequency. What do you need such a high voltage for?

 

[ashley0927]

hi crut show,

thanks for reply ,as I plan to display my DDS function generator on exhibition with this

for the vibration...

 

[ashley0927]

That device has a worst-case maximum output voltage of 3Vpp.

20Vpp is a rather large signal level for such a high frequency. What do you need such a high voltage for?

how about using this device https://www.analog.com/static/imported-files/data_sheets/AD8367S.pdf??

 

[ronv]

I don't think you need such a high frequency. It seems like you can hear all the frequencies in the demo so they are below 20KHz. But what you probably will need is a good audio amplifier to get enough power to drive the speaker or whatever is moving the plate.

Pretty neat.

 

[ashley0927]

I don't think you need such a high frequency. It seems like you can hear all the frequencies in the demo so they are below 20KHz. But what you probably will need is a good audio amplifier to get enough power to drive the speaker or whatever is moving the plate.

Pretty neat.

That just for demostration on the exhibition.as my lecture request the frequency up to 40 MHz,so this is the most headache part for the design of amplifier ..any suggestion on how for the designing of the amplifier circuit?
Thanks

 

[dr pepper]

An Ad600 hf agc chip will do the trick... but they are expensive.
Heres a linky:

https://electronics.stackexchange.c...tabilize-output-gain-after-low-pass-filtering

 

[ronv]

Take a look at this circuit. Then look at the LM7171 as the amplifier IC. I think it would take 2 to get to 20 volts.

https://midnightdesignsolutions.com/dds60/

**broken link removed**

 

[JimB]

my lecture request the frequency up to 40 MHz

If you are mechanically vibrating a plate, what sort of transducer do you expect to work at 40Mhz?

I suggest you query your lecturer about this, did he REALLY mean 40 Mhz, or 40 khz?

JimB

 

[dr pepper]

I didnt know there was a daughter card for the 8950 series ron, thats cool.

 

[ashley0927]

Take a look at this circuit. Then look at the LM7171 as the amplifier IC. I think it would take 2 to get to 20 volts.

https://midnightdesignsolutions.com/dds60/

**broken link removed**

Hi ronv,
I take a look of the daughter card,erm.it indeed a good solution,but I already built up a DDS generator by myself,so if I straight buy the daughter card,then the work I done before will be wasted.and my lecture disallow me use daughter card,she want me to design the amplifier and automatic gain control amplifier