Mask control device for LSI tester

A mask control device comprising:

• an address generator for generating a random pattern address, a serial pattern address, and a pattern mode signal;
• an expected waveform random pattern memory for storing random pattern expected waveform data designating expected waveform data to be outputted from a device under test (DUT) in a random pattern test;
• a mask waveform random pattern memory for storing random pattern mask waveform data for use in the random pattern test;
• an expected waveform serial pattern memory for storing serial pattern expected waveform data designating expected waveform data to be outputted from the DUT in a serial pattern test;
• a mask waveform serial pattern memory for storing serial pattern mask waveform data for use in the serial pattern test;
• a first pin selector for arranging the serial pattern expected waveform data to generate serial pattern expected waveform data corresponding to tester pins and for generating serial mode designating signals designating pins to which the serial pattern test is to be applied;
• a second pin selector for arranging the serial pattern mask waveform data to generate serial pattern mask waveform data corresponding to the tester pins;
• a selector for selecting the random pattern expected waveform data or the serial pattern expected waveform data generated by the first pin selector based on the serial mode designating signals;
• a comparator for comparing output waveform data obtained from the DUT with the random pattern expected waveform data or the serial pattern expected waveform data selected by the selector;
• a logical operation circuit comprising
• a first AND gate for outputting logical products of the serial mode designating signals and the serial pattern mask waveform data corresponding to the tester pins as select signals,
• an inverter for inverting the select signals, and
• a second AND gate for modulating the random pattern mask waveform data based on the inverted select signals from the inverter to generate mask waveform data;
• and
• a mask control circuit for carrying out a mask control of a comparison result of the comparator using the mask waveform data generated by the logical operation circuit.