| 摘要 |
PURPOSE:To make it possible to perform the characteristic test of LSI in an optimum state, by changing the constant of a test oscillator so as to conform the oscillation frequecy of LSI with predetermined frequency even if the constant of the oscillator provided to the internal side of LSI is varied. CONSTITUTION:A test oscillator has resistors R1-R4 and switches SW1-SW4 which are connected between terminals OUT, OUT2. SW1-SW3 are closed while SW3 is opened and only R4 is inserted between the terminals. Oscillation frequency due to the resistance value is compared to matching frequency F and, when it is high, SW3 is opened and SW1, SW2, SW4 are closed and the resistor R3 is inserted between the terminals. Because R4 is larger than R3, the oscillation frequency of LSI becomes high. This oscillation frequency is compared to F and, if it is high, SW2, SW3 are opened while SW1, SW4 are closed to insert the resistors R2, R3 between the terminals. By repeating the above mentioned operations, the oscillation frequency of LSI can be matched with arbitrary frequency such as the optimum frequency of a system. |
