Illustrations of the benefits of low TCR may be found within thousands of successful applications. In this paper, we’ll see how low TCR and high precision resistors benefits below applications.

 

Precision Instrumentation

Transmille, a leading UK manufacturer of high-accuracy digital multimeters (DMMs), was seeking a resistor component for a new series of 8.5- and 7.5-digit units. To achieve necessary 8.5-digit accuracy, the specified resistor needed to offer extremely low TCR, high-precision, repeatability, low thermal EMF, low noise, long-term stability and minimal harmonic distortion. As the multimeter was based on an analog circuit design, the resistor needed to have minimal drift from initial values when operating above room temperatures. 
 

 

Diode Laser Current Drivers

In another example, low-cost and easy-to-use diode lasers are a virtual measurement staple in experimental atomic physics. For a diode laser to maintain its frequency, output power, current and temperature, careful regulation of parameters is required. To best manage costs, the Physics Department at California State University looked to construct its own low-cost, low-noise current source for use with its in-laboratory diode lasers. To generate a suitably stable laser stream, the current sense resistor needed to be resistant to both internal and external temperature drifts, have a high-power rating, and a low thermal EMF.  The most critical element of the current driver is the sub-circuit, responsible for current regulation, since laser stability must not exceed overall sense resistor stability. In this application, the use of traditional commercial current controllers was too cost-prohibitive. The viable resistor solution therefore needed to be both low-cost and high-precision.
 

 

Metrology Secondary Reference

 

In another example, VSL, the National Metrology Institute (NMI) of the Netherlands, seeking for a high-precision resistor solution, as a secondary reference standard in its quantum Hall resistance (QHR) experiments. QHR is the globally recognized primary quantum resistance standard, with values of around 12.9 kΩ and 6.45 kΩ. To serve as an adequate secondary reference standard, VSL needed a cost-effective, high-precision resistor, the values of which needed to closely match those of the primary QHR standard, yet offer a well-defined four-terminal configuration, low noise, low TCR and no RH effect, along with excellent long-term stability.

 

Microhm Electronic MVR series, EE series, NLT series,  and s NSR series are low TCR and high precision resistors. They also can be used in precision instrumentation, diode Laser current drivers and Metrology Secondary Reference.