• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.6
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• pp.408-420
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• 2003

This paper describes a Delay Locked Loop (DLL) circuit having two advancements : 1) a dual loop operation for a wide lock-range and 2) programmable replica delays using antifuse circuitry and internal voltage generator for a post-package skew calibration. The dual loop operation uses information from the initial time-difference between reference clock and internal clock to select one of the differential internal loops. This increases the lock-range of the DLL to the lower frequency. In addition, incorporation with the programmable replica delay using antifuse circuitry and internal voltage generator allows for the elimination of skews between external clock and internal clock that occur from on and off-chip variations after the package process. The proposed DLL, fabricated on 0.16m process, operates over the wide range of 42MHz - 400MHz with 2.3v power supply. The measured results show 43psec peak-to-peak jitter and 4.71psec ms jitter consuming 52㎽ at 400MHz.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.180-187
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• 1996

This paper describes a post-layout simulation method using VHDL and C for verifying the architecture of antifuse-based FPGAs and the dedicated CAD system. An antifuse-based FPGA consists of programming circuitry including decoding logic, logic modules, segmented tracks, antifuses and I/O pads. The VHDL model which includes all these elements is used for logic verification and programming verification of the implemented circuit by reconstructing the logic circuit from the bit-stream generated from layout tool. The implemented circuit comprises of logic modules and routing networks. Since the routing delay of the complex networks is comparable to the delay of the logic module in the FPGA, the accurate post-layout simulation is essential to the FPGA system. In this paper, the C program calculates the delay of the routing netowrks using SPICE, elmore or horowitz delay models and the results feedback to the VHDL simulation. Critical path anc be found from this post-layout simulation results.