Load Cell Amplifiers

Function of a Signal Conditioner

The function of a signal conditioner is to pick up the signal from the load cell and convert it into a higher level of an electrical signal. Signal conversion is often used by industrial applications, especially those that use a wide range of sensors to perform measurements. The output signals need to be converted to be usable for the instruments they are connected to. Through the use of a signal conditioner, any sensor signal can be converted to any standard process signal.

Linearization

When the signal produced by a load cell does not have a straight-line relationship with the physical measurement, certain signal conditioners can perform linearization. The nonlinear output is interpreted by the signal conditioner and translated to the data acquisition device as a linear signal.

Amplification

Amplification is the process of increasing the signal for processing or digitization. An ADC has a particular dynamic range it is necessary to adjust the amplitude of the received signal to efficiently utilize the available dynamic range of the ADC. There are two ways that signal amplification can be performed; by increasing the resolution of the input signal, or by increasing the signal-to-noise ratio.

Attenuation

Attenuation, the opposite of amplification, is necessary when voltages to be digitized are beyond the ADC range. This form of signal conditioning decreases the input signal amplitude so that the conditioned signal is within the ADC range. Attenuation is typically necessary when measuring voltages that are more than 10 V.

Excitation

Excitation is required for strain gauge load cells which require external voltage or current excitation. Measurements are usually made with a current source that converts the variation in resistance to a measurable voltage. Strain gages, which are very-low-resistance devices, typically are used in a Wheatstone bridge configuration with a voltage excitation source.

Filtering

Another important function of a signal conditioner is filtering, and this is where the signal frequency spectrum is filtered to reject any noise within a certain frequency range. A digital filter is a mathematical filter used to manipulate a signal, such as blocking or passing a particular frequency range.