Semiconductor leakage current detector and leakage current measurement method, semiconductor leakage current detector with voltage trimming function and reference voltage trimming method, and semiconductor integrated circuit thereof

The semiconductor integrated circuit comprising

• a semiconductor leakage current detector which determines whether or not a current to be measured is greater than a reference current,
• wherein said semiconductor leakage current detector includes:
• a first analog switch which causes the current to be measured to flow or to be cut off;
• a second analog switch which causes the reference current to flow or to be cut off;
• an integral capacitor which is connected to said first analog switch and said second analog switch, and is charged with the current to be measured or the reference current;
• a discharge unit operable to discharge said integral capacitor;
• and
• a comparison unit operable to compare a reference voltage with each of:
• an integral voltage generated in said integral capacitor by the reference current after the discharge of said integral capacitor;
• and an integral voltage generated in said integral capacitor by the current to be measured after the discharge of said integral capacitor,
• wherein said comparison unit is operable to perform
• a first comparison of comparing the reference voltage with the integral voltage generated in said integral capacitor by the reference current after the discharge of said integral capacitor, and
• a second comparison of comparing the reference voltage with the integral voltage generated in said integral capacitor by the current to be measured after the discharge of said integral capacitor, and
• said semiconductor leakage current detector is operable to determine whether or not the current to be measured is greater than the reference current, based on outputs of said comparison unit as results of the first and second comparisons.

The semiconductor integrated circuit further comprising:

• a reference register which holds trimming data;
• a reference voltage source which generates a constant voltage in accordance with the trimming data;
• a first voltage divider circuit which divides the constant voltage and outputs, as the reference voltage, the divided constant voltage to said comparison unit;
• and
• an analog multiplexer which connects one of said integral capacitor and an external pad to an integration voltage input of said comparison unit,
• wherein said control unit is operable to control said comparison unit so as to compare the reference voltage with a signal inputted via said analog multiplexer from the external pad, and to update the trimming data in said reference register based on the comparison result.

A leakage current measurement method for use in a semiconductor integrated circuit,

• wherein the semiconductor circuit includes:
• a first analog switch which causes the current to be measured to flow or to be cut off;
• a second analog switch which causes the reference current to flow or to be cut off;
• an integral capacitor which is connected to the first analog switch and the second analog switch, and is charged with the current to be measured or the reference current;
• a discharge unit operable to discharge the integral capacitor;
• and
• a comparator operable to compare a reference voltage with each of:
• an integral voltage generated in the integral capacitor by the reference current after the discharge of the integral capacitor;
• and an integral voltage generated in the integral capacitor by the current to be measured after the discharge of the integral capacitor,
• said leakage current measurement method comprising:
• a calibration step of comparing the reference voltage with the integral voltage generated in the integral capacitor by the reference current after the discharge of the integral capacitor;
• a test step of comparing the reference voltage with the integral voltage generated in the integral capacitor by the current to be measured after the discharge of the integral capacitor;
• and
• a determination step of determining whether or not the current to be measured is greater than the reference current, based on results obtained in said calibration step and said test step.

A reference voltage trimming method for use in the semiconductor integrated circuit,

• wherein the semiconductor integrated circuit includes
• a semiconductor leakage current detector which determines whether or not a current to be measured is greater than a reference current,
• the semiconductor leakage current detector has:
• a first analog switch which causes the current to be measured to flow or to be cut off;
• a second analog switch which causes the reference current to flow or to be cut off;
• an integral capacitor which is connected to the first analog switch and the second analog switch, and is charged with the current to be measured or the reference current;
• a discharge unit operable to discharge the integral capacitor;
• and
• a comparison unit operable to compare a reference voltage with each of:
• an integral voltage generated in the integral capacitor by the reference current after the discharge of the integral capacitor;
• and an integral voltage generated in the integral capacitor by the current to be measured after the discharge of the integral capacitor,
• the comparison unit is operable to perform a first comparison of comparing the reference voltage with the integral voltage generated in the integral capacitor by the reference current after the discharge of the integral capacitor, and a second comparison of comparing the reference voltage with the integral voltage generated in the integral capacitor by the current to be measured after the discharge of the integral capacitor, and
• the semiconductor leakage current detector is operable to determine whether or not the current to be measured is greater than the reference current, based on outputs of the comparison unit as results of the first and second comparisons,
• the semiconductor integrated circuit further has:
• a timer which measures an elapsed time after the discharge of the integral capacitor;
• a memory for storing the predetermined time;
• and
• a control unit operable to control the first and second comparisons,
• the control unit is operable to store, into the memory, the elapsed time as the predetermined time, when the output of the comparison unit is inverted in the first comparison, and
• in the second comparison, it is determined whether or not the current to be measured is greater than the reference current in accordance with the output of the comparison unit, when the elapsed time reaches the predetermined time stored in the memory,
• the semiconductor integrated circuit further has:
• a reference register which holds trimming data;
• a reference voltage source which generates a constant voltage in accordance with the trimming data;
• a first voltage divider circuit which divides the constant voltage and outputs, as the reference voltage, the divided constant voltage to the comparison unit;
• and
• an analog multiplexer which connects one of the integral capacitor and an external pad to an integration voltage input of the comparison unit, and
• the control unit is operable to control the comparison unit so as to compare the reference voltage with a signal inputted via the analog multiplexer from the external pad, and to update the trimming data in the reference register based on the comparison result,
• said method comprising
• a target voltage apply step, a first intermediate value search step, a comparator input inversion step, a second intermediate value search step, and a trimming value average step that are sequentially executed,
• wherein in said target voltage apply step, the reference voltage is applied,
• in said first intermediate value search step, a first trimming intermediate value is obtained, the first trimming intermediate value being a boundary value at which an output of the comparator is inverted,
• in said comparator input inversion step, inputs of the comparator are switched by the inversion analog multiplexer,
• in said second intermediate value search step, a second trimming intermediate value is obtained, the second trimming intermediate value being a boundary value at which an output of the comparator is inverted, and
• in a trimming average step, a trimming value is obtained by taking an average between the first trimming intermediate value and the second trimming intermediate value, as a trimming result of the reference voltage.