The PRTD 4 to 20 mA loop transmitter with constant current PRTD excitation that relies on 2nd order software nonlinearity correction math

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Other Materials from the Main Document

• Article «Positive analog feedback linearizes 4 to 20 mA PRTD transmitter»
• Figure 1. The PRTD 4 to 20 mA loop transmitter with constant current PRTD excitation that relies on 2nd order software nonlinearity correction math
• Figure 2. A platinum RTD bridge where feedback to the bridge from A3 linearizes the circuit
• Figure 3. A PRTD transmitter based on the classic LM10 op-amp plus a 200 mV precision reference combo
• Figure 4. Positive feedback reduces linearity error to < ±0.05 °C over -127 °C to +380 °C. The x-axis = I_O (mA), left y-axis = PRTD temperature, right y-axis = linearity error. T°C = 31.7(I_O - 8 mA)
• Figure 5. Linearized temperature transmitter modified for a post-assembly tweaking using his procedure