AD835

Hi-

I have moved this question about the AD835 to the Amplifiers community.  Someone here should be able to assist you.

Regards,

AndyR

EngineerZone Support Community Manager

Hi mira_21,

I replied to your other post. I thought that the DDS community might be able to help you since they have single chip solution that is capable of producing BPSK signals. But apparently, you wanted to go with a discrete BPSK circuit that makes use of the AD835 multiplier IC. Is this correct? Please take a look at  my reply to the other thread.

Thank you,

Neil

Hi Mr.Neil,

thank you so much for your attention about my problem. yeah, i wanna make BPSK modulator using AD835 cause i have bought it. here i attach a file about my BPSK circuit. sorry if this circuit looked bad, cause i'm newbie.

After you look at my circuit, please tell me what is wrong with my circuit cause the output was not producing BPSK signal.

Thank you,

Mira_21

Hi Mira_21,

Thank you for clarifying that. I looked at your actual circuit and I noticed that R3 is connected differently as compared to the circuit in the paper you were referring. Have you checked on this?

Also, I am curious on the signals at the X1 and Y1 pins. Could you take some scope shots on these input pins? I want to make sure that we are having the correct input levels for the AD835. If possible, please include the output bpsk signal on the scope shot.

Regards,

Neil

Hi,

There was no scope shots for the inputs on the document the you attached. Could you re-send the scope shots of the two inputs on the same picture?

On the paper you sent earlier, the oscillator output is connected to the X1 pin via a resistor divider. However, the one you built had a different resistor configuration. I am not sure though if this could affect your circuit as long as the input pins of the AD835 are within the specified voltage range.

Thanks.

additional discussion added to reply. Message was edited by: Neil Kane Jacalan

Hi Mr.Neil.

Tq for your respon.

i attached the input and output of my circuit.

please tell me what was wrong with my circuit.

about R3 that i have made, i thought it similiar to the circuit of the paper that i have sent to you. 

thank you.

mira_21

mr. neil, this is my scope shot of INPUT X1 and Y1. thank you..

Hi,

Thank you for the scope shots. Your inputs seem to be good. However, are the digital signal and carrier signal synchronized? In order to properly implement BPSK, the carrier frequency must be an exact multiple of the digital bit clock such that they cross the zero level at the same time. I can't tell whether your carrier and digital clock are synchronized based on your AD835 schematic and input scope shots. The reason why I asked for the inputs to be on the same scope shot (or the same picture) is to see whether they cross the zero level at the same time.

Best regards,

Neil