Patent ID: 6094045
Filing Date: 2000-07-25
Classification: G01R

Abstract:
An input ranging circuit, comprising:(a) an input terminal adapted for receiving an input voltage;(b) a mode switch coupled to said input terminal for selecting one of an a.c. volts mode, a d.c. volts mode, and an ohms mode;(c) a resistor array coupled to said mode switch, said resistor array comprising an input resistor, a reference resistor, a plurality of divider resistors, and a plurality of feedback resistors, said input resistor coupled to said mode switch to receive said input voltage;(d) an AC amplifier coupled to said feedback resistors to produce an a.c. output voltage;(e) a current source comprising an amplifier coupled to said reference resistor and said plurality of divider resistors to produce a selectable current;(f) a switch array coupled to said input resistor, said plurality of divider resistors, and said AC amplifier, said switch array comprising a divider bus, a source bus, and a sense bus, and a plurality of switches coupled between each of said divider bus, said source bus, and said sense bus and said input resistor and said plurality of divider resistors wherein:(i) in said d.c. volts mode, a d.c. output voltage is developed from said sense bus coupled to a junction of said input resistor and a selected one of said plurality of divider resistors through said divider bus;(ii) in said a.c. volts mode, said a.c. output voltage is developed from said AC amplifier coupled to said junction of said input resistor and said selected one of said plurality of divider resistors through said divider bus and said sense bus; and,(iii) in said ohms mode, an said selectable current is provided to said input terminal.