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A method and apparatus for obtaining a voltage-isolated measurement channel in a measurement instrument is provided. An input signal is multiplied with a clock signal to obtain a modulated input signal that is coupled to an input winding of a balanced transformer. The modulated input signal is elect

A method and apparatus for obtaining a voltage-isolated measurement channel in a measurement instrument is provided. An input signal is multiplied with a clock signal to obtain a modulated input signal that is coupled to an input winding of a balanced transformer. The modulated input signal is electromagnetically coupled from the input winding to an output winding. At the same time, the input winding and the output winding are voltage-isolated, meaning that the portion of the measurement channel coupled to the input winding is “floated”with the input signal whereas the remaining portion of the measurement channel is referenced to instrument ground. A sampling circuit coupled to the output winding samples the modulated input signal in the manner of a synchronous detector to extract the original input signal voltage which is provided to an analog to digital converter which generates the digital measurement values. Each measurement channel is voltage-isolated from the instrument and from all other measurement channels in the instrument.

대표청구항 ▼

A voltage-isolated measurement channel, comprising: (a) a multiplier adapted for receiving an input signal and coupled to a clock signal, said multiplier multiplying said input signal by said clock signal to produce a modulated input signal at a multiplier output; (b) a transformer coupled to said m

A voltage-isolated measurement channel, comprising: (a) a multiplier adapted for receiving an input signal and coupled to a clock signal, said multiplier multiplying said input signal by said clock signal to produce a modulated input signal at a multiplier output; (b) a transformer coupled to said multiplier output to receive said modulated input signal at an input winding, said transformer reproducing said modulated input signal in an output winding wherein said input winding is voltage-isolated from said output winding by a voltage isolation barrier, (c) a sampling circuit coupled to said output winding to receive said modulated input signal and further coupled to said clock signal to capture voltage samples of said modulated input signal responsive to said clock signal; and (d) an analog to digital converter coupled to said sampling circuit to receive said voltage samples and produce digital measurement values from said voltage samples.