Is this in spice simulation, or for a real world device.
Assuming the real world, what is your strain gauge configuration, half or full bridge, and the corresponding input configuration on your amplifier or ADC.
A strain gauge normally has a full scale output of 1-3mV/volt of drive, and a band width from DC to hundreds of Hz.
A function generator cannot supply that voltage directly, an attenuator on the output would be needed. Noise from the generator needs to be considered as well, the attenuator helps in that regard, since the generator can be run with higher output voltages. However, don't expect to get good results at the low end. I typically see 300nV per bit or less from a 16 bit ADC in my applications.
A battery, some fixed resistors, and a decade resistance box is probably a better bet.
Further comment when you have described what the configuration of your strain gauge/measurement device input is like,
cheers,
Richard
