Abstract: An OFDM receiver (1) is provided which includes a clock-frequency error calculation circuit (41) to calculate a difference in clock frequency between a clock for a received signal and an operation clock used in the receiver (1), and a guard correlation/peak detection circuit (12) to determine an autocorrelation of a guard interval and detect a peak timing of the correlation signal. The guard correlation/peak detection circuit (12) incorporates a free-running counter, and outputs a count of the free-running counter at the peak timing to the clock-frequency error calculation circuit (41). The clock-frequency error calculation circuit (41) uses a plurality of time-change rate detection circuits provided at different time intervals to calculate a time-change rate of an input count. The clock-frequency error calculation circuit (41) plots the time-change rates to generate a histogram and calculates a clock-frequency error from the histogram.

Abstract: An IC connection/disconnection mechanism and a method for carrying out the same comprises a lifting plate for mounting and lifting the IC having a lead frame thereon, a measuring socket mounted on a base and having terminals capable of contacting the terminals of the IC, stoppers mounted on the base, first springs coiled around stoppers for supporting the lifting plate, a pusher having recesses at both sides thereof in which presser pins are housed corresponding to the stoppers, and second springs coiled around the presser pins and having resilience force greater than that of the first springs. Due to difference of the resilience forces of the first and the second springs, firstly the pusher is moved away from the lifting plate, then the lifting plate makes the IC move away from the measuring socket.

Abstract: A probe card clamping and changing mechanism comprising a probe card clamping mechanism and a probe card conveying mechanism. The probe card clamping mechanism comprises a pair of clamping blocks each having a groove for receiving a portion of the periphery of a probe card and two guide holes, a pair of guide members slidably received through the guide holes of the clamping blocks so as to slidably support support the clamping blocks axially slidably for parallel motion with the respective grooves of the clamping blocks facing each other, two pairs of links interconnecting the clamping blocks so that the clamping blocks are moved simultaneoulsy toward and away from each other, an actuator connected to one of the clamping blocks to move the same toward and away from the other, a pair of guide rails for guiding pins pivotally joining two pairs of the links, respectively, so that when the clamping block connected to the actuator is moved by the actuator, the other clamping block is moved accordingly.