Measuring Input Capacitance with Automatic Test Equipment (ATE)

Abstract

A method for measuring an input capacitance of a pin of an electronic device includes, using a tester including Pin Electronics (PE), obtaining a first capacitance measurement while the pin is disconnected from the PE, and a second capacitance measurement while the pin is connected to the PE. The input capacitance of the pin is calculated from the first and second capacitance measurements.

1 . A method for measuring an input capacitance of a pin of an electronic device, the method comprising:
 using a tester comprising Pin Electronics (PE), obtaining a first capacitance measurement while the pin is disconnected from the PE, and a second capacitance measurement while the pin is connected to the PE; and   calculating the input capacitance of the pin from the first and second capacitance measurements.   
     
     
         2 . The method according to  claim 1 , wherein obtaining each of the first and second capacitance measurements comprises driving the PE with one or more predefined currents using a current source, and measuring one or more respective voltages that form across the PE responsively to the currents. 
     
     
         3 . The method according to  claim 2 , wherein the one or more predefined voltages comprise at least two voltages, and wherein calculating the input capacitance comprises deriving from the voltages a voltage slope as a function of time, and calculating the input capacitance from the voltage slope. 
     
     
         4 . The method according to  claim 1 , wherein obtaining the first and second capacitance measurements comprises prompting a user to disconnect the pin from the PE before obtaining the first capacitance measurement, and prompting the user to connect the pin to the PE before obtaining the second capacitance measurement. 
     
     
         5 . An apparatus for measuring an input capacitance of a pin of an electronic device, the apparatus comprising:
 Pin Electronics (PE), configured to connect to the pin; and   a controller, configured to:
 obtain a first capacitance measurement while the pin is disconnected from the PE, and a second capacitance measurement while the pin is connected to the PE; and 
 calculate the input capacitance of the pin from the first and second capacitance measurements. 
   
     
     
         6 . The apparatus according to  claim 5 , and comprising a current source, wherein the controller is configured to obtain each of the first and second capacitance measurements by instructing the current source to drive the PE with one or more predefined currents, and measuring one or more respective voltages that form across the PE responsively to the currents. 
     
     
         7 . The apparatus according to  claim 6 , wherein the one or more predefined voltages comprise at least two voltages, and wherein the controller is configured to derive from the voltages a voltage slope as a function of time, and to calculate the input capacitance from the voltage slope. 
     
     
         8 . The apparatus according to  claim 5 , wherein the controller is configured to prompt a user to disconnect the pin from the PE before obtaining the first capacitance measurement, and to prompt the user to connect the pin to the PE before obtaining the second capacitance measurement. 
     
     
         9 . A computer software product for measuring an input capacitance of a pin of an electronic device, the product comprising a tangible non-transitory computer-readable medium in which program instructions are stored, which instructions, when read by a processor that is coupled to Pin Electronics (PE) configured to connect to the pin, causes the processor to:
 obtain a first capacitance measurement while the pin is disconnected from the PE, and a second capacitance measurement while the pin is connected to the PE; and   calculate the input capacitance of the pin from the first and second capacitance measurements.