Summation of two signals

[Japhet55]

Whats the best way to sum two voltages in design. I have two dc voltages, one from a low pass filter and another from an external control signal. Whats the best way to add these two voltagee before inputting them to a single pin?

 

[thunderdantheman]

You'll need to use an op-amp configured as an adder... have a read of this it's an excelent resorce for op-amps and their various configurations.

 

[thannara123]

Whats the best way to sum two voltages in design. I have two dc voltages, one from a low pass filter and another from an external control signal. Whats the best way to add these two voltagee before inputting them to a single pin?

Hi may i know the purpose of summation of those signals ?

 

[Japhet55]

Hi may i know the purpose of summation of those signals ?

Hi, thank you for your response. I intend on using the summed voltage as an input to a VCO. The external voltage is passed through a Potentiometer to kind of act as a phase shifter or control the frequency on what the VCO will output

 

[KlausST]

Hi,

Often used: just two resistors.
But it's no "perfect" summation. The (only) drawback is that you lose a bit of gain.

If there is an active filter ... there is a good chance that there is one node with almost perfect conditions to "add" the external signal.

For better assistance we need to see your schematic.

Klaus

 

[danadakk]

MFB might be one possibility. Here example is Khz LPF

Regards, Dana.

 

[Japhet55]

				Hi, Often used: just two resistors. But it's no "perfect" summation. The (only) drawback is that you lose a bit of gain. If there is an active filter ... there is a good chance that there is one node with almost perfect conditions to "add" the external signal. For better assistance we need to see your schematic. Klaus What component can i use to add the voltage from the potentiometer with the one from the Low pass filter?

 

[KlausST]

Hi,

What component can i use to add the voltage from the potentiometer with the one from the Low pass filter?

We gave some solutions. What's wrong with them?

Klaus