Switchable voltage divider

[hanover100]

Hello all,
I need your recommendation for designing voltage divider consisting XtimesR resistors (R is about 100 ohm).
By switching, I want to connect the required voltage (100mV, 150mV etc.) to the output.
Since the switchers (mosfet transistors) has Ron and the swiching affects the value of voltage, what should I du to reduce negative these affects?
I would be thanks for any recommend

 

[crutschow]

what should I du to reduce negative these affects?

You could buffer the voltage from the switches with a non-inverting (follower) op amp, which would draw negligible current from the switch.

 

[D.A.(Tony)Stewart]

I need your recommendation for designing voltage divider consisting XtimesR resistors (R is about 100 ohm).
By switching, I want to connect the required voltage (100mV, 150mV etc.) to the output.

That depends where you switch. Input or output.
If you choose input with a high side switch then the shunt R=100 is fixed and RdsOn or Rce for the PNP is negligible or predictable for voltage drop.

 

[danadakk]

Curious :

1) Why not use a DAC followed by a buffer (which could be inside DAC) ?
2) How many V's need to be muxed ?
3) Range of V's to be output ?
4) Speed of scanning array ?
5) What is your error tolerance goal ? And accuracy ?
6) What are you doing with the V, feeding to ADC ? If so resolution/bits of ADC ?


Regards, Dana.

 

[dick_freebird]

If the "load" is high-Z then an analog mux with N taps
would be simplest and not perturb the DC value (other
than its inherent leakage).

 

[D.A.(Tony)Stewart]

As usual, a question with better specs gives better answers.