Analog modulator

user4646208

Other Parts Discussed in Thread: TS12A12511

I need to modulate the analog signal from -2.5V to + 2.5V with PWM 500kHz

Now I use TS12A12511 and DAC, but TS12A12511 is very noisy from the carrier frequency. This becomes very noticeable when I modulate voltages around 100mV.

My question is how can I still solve this problem?
Perhaps I need a completely different approach?

over 6 years ago

0 user4646208 over 6 years ago

Intellectual 580 points

I'm sorry, I forgot to attach pictures

0 Adam Torma over 6 years ago in reply to user4646208

TI__Mastermind 45575 points

user4646208,

I'm not sure I understand what noise you are talking about. Do you have a scope capture of the noise.

Are you placing +2.5 V DC on the NO pin and -2.5 V DC on the NC pin? Then you are using the IN pin to toggle the COM pin between NO and NC at 500kHz?

what are you connecting to channel out?

What conditions are you using 100mV instead of +/- 2.5 V?

Thank you,
Adam

0 user4646208 over 6 years ago in reply to Adam Torma

Intellectual 580 points

The voltage at the contacts NO and NC is set using DAC (positive and negative)

COM connects to a Howland current source.

The fact is that the voltage on the NO and NC is "compressed" with a frequency of up to 10kHz

NO and NC voltages are user-defined, the spread can be + 2.5V and -2.5V or + 0.1V - 0.04V or absolute any other within +/- 2.5 V

0 Adam Torma over 6 years ago in reply to user4646208

TI__Mastermind 45575 points

user4646208,

Are you saying that the signal amplitude is reduced when toggling the IN pin faster than 10kHz? Does it work at 1kHz?

This could be due to your bus capacitance not allowing the signal to settle at the desired voltage fast enough before switching to the other channel.

Do you have a scope capture of what you are seeing?

Adam

0 Adam Torma over 6 years ago in reply to Adam Torma

TI__Mastermind 45575 points

user4646208,

I haven't heard from you so I'm going to assume you solved the issue and close this thread. If you have additional questions you may reply here to reopen it or create a new one.

Thank you,
Adam

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Analog modulator