Synthetic Dpot evades problems using FET shunt, precision fixed resistors, and op-amp

Authors	Stephen Woodward
Main Document	Article «Synthesize precision Dpot resistances that aren't in the catalog»
Description	Figure 2
File Format / Size	PDF / 19 Kb
Document Language	English

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Article «Synthesize precision Dpot resistances that aren't in the catalog»

Figure 1. Classic variable resistance with the series connection of a manually adjusted rheostat-connected pot and a fixed resistor
Figure 2. Synthetic Dpot evades problems using FET shunt, precision fixed resistors, and op-amp
Figure 3. Synthetic rheostat design example where R_MAX= 20k and R_MIN = 1k
Figure 4. Performance of Figure 3's circuit with values shown, the linear relationship between N and I_AВ conserves the Dpot's limited 8-bit resolution
Figure 5. Two buffer amps remove R_AB from R_MAXequation, allowing for an R_MAX extending far into the megaohms

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