Integration type input circuit and method of testing it

A method of testing an integrated circuit device, comprising:

• applying a reference signal having a first voltage value to an input circuit of the integrated circuit device;
• applying an input signal having a second voltage value to the input circuit,
• wherein the second voltage value is within a predetermined range of the first voltage value;
• applying a sequentially varying control voltage to the input circuit;
• and
• determining a drive capability of a transistor within the input circuit which receives one of the reference signal and the input signal based on a value of the control voltage at a selected time.

An input circuit for an integrated circuit, comprising:

• input signal processing means for receiving an input signal, generating a reference value, and integrating the input signal;
• a comparing circuit which receives the reference value and the integrated input signal and outputs a logic value related to the input signal;
• and
• a test circuit which applies a sequentially varying voltage to the input signal processing means and determines a value of the sequentially varying voltage when the logic value changes from one state to another;
• a clock input terminal to which an external clock signal is applied;
• and
• a clock signal generating circuit connected to the clock input terminal,
• said clock signal generating circuit providing a control signal derived from the external clock signal,
• wherein the input signal processing means receives the control signal and integrates the input signal based upon the control signal.

An input interface circuit comprising:

• a clock input terminal receiving an external clock signal;
• a control signal generating circuit connected to the clock input terminal and generating a control signal based on the external clock signal;
• and
• integrating means for receiving an input signal and the control signal and integrating the input signal for a time period controlled by the control signal,
• wherein a phase deviation between the external clock signal and the control signal is determined by the integrated input signal,
• wherein the input signal is a digital signal.