Digital multi-meter with LCR function

A front end chip used in a data acquisition apparatus for measuring parameters from a device under test, output of said front end chip being fed to next stage process circuit, and then to display device of said data acquisition apparatus to show the measured parameters, said data acquisition apparatus being adopted in a housing, said front end chip comprising:

• a multi-meter measuring circuit electrically coupled to a first terminal and a second terminal, said housing respectively providing a hole for said first terminal and said second terminal, thus enabling objects outside exterior surface of said housing electrically coupled to said first terminal and said second terminal, said first terminal being coupled to a dc resistor input path having a dc resistor input switch and a first protection device, output of said digital multi-meter being first kind of output signal of the data acquisition apparatus;
• and
• a LCR measuring circuit comprising an impedance measuring circuit and an auto-zero amplifier selectively coupled respectively to said first terminal with one LCR input path and to said second terminal through the other LCR input path, said LCR measuring circuit being selectively coupled respectively to said first terminal with one voltage feeding path and to said second terminal with the other voltage feeding path, each of the two LCR input paths and the two voltage feeding paths having a LCR switch, status change of all LCR switches being synchronized, one of said two voltage feeding paths electrically couples said LCR measuring circuit to said first terminal through said first protection device, when all LCR switches closed, a voltage drop on said device under test being amplified by said auto-zero amplifier, then fed to said impedance measuring circuit to determine the impedance of said device under test, thereby acquired a second kind if output, user's operation makes one of said first kind of output and said second kind of output selected as said output of said data acquisition apparatus.

Data acquisition apparatus enclosed in a housing for measuring parameters from a device under test, output of the data acquisition apparatus being fed to a next stage process circuit of said data acquisition apparatus, then subsequently fed to a display device of the handheld housing to show the parameters, said data acquisition apparatus comprising:

• a digital multi-meter comprising a multi-meter measuring circuit, said multi-meter measuring circuit being electrically coupled to a first terminal, a second terminal, a first current terminal, and a second current terminal, said housing respectively providing a hole for said first terminal, said second terminal, said first current terminal, and said second current terminal, thus enabling objects outside exterior surface of said housing electrically coupled to said first terminal, said second terminal, said first current terminal, and said second current terminal, said first terminal being coupled to a dc resistor input path having a dc resistor input switch and a first protection device, output of said digital multi-meter being first kind of output signal of the data acquisition apparatus;
• and
• a LCR measuring circuit comprising an impedance measuring circuit and an auto-zero amplifier selectively coupled respectively to said first current terminal with one LCR input path, and to said second terminal through the other LCR input path, said LCR measuring circuit being selectively coupled respectively to said first current terminal with one voltage feeding path, and to said second terminal with the other voltage feeding path, each of the two LCR input paths and the two voltage feeding paths having a LCR switch, status change of all LCR switches being synchronized, one of said two voltage feeding paths electrically couples said LCR measuring circuit to said first terminal through said first protection device, when all LCR switches closed, a voltage drop on said device under test being amplified by said auto-zero amplifier, then fed to said impedance measuring circuit to determine the impedance of said device under test, thereby acquired a second kind if output, user's operation makes one of said first kind of output and said second kind of output selected as said output of said data acquisition apparatus.