A new circuit for at-speed scan SoC testing

It is very important to detect transition-delay faults and stuck-at faults in system on chip （SoC） under 90 nm processing technology, and the transition-delay faults can only be detected by using an at-speed testing method. In this paper, an on-chip clock （OCC） controller with a bypass function based on an internal phase-locked loop is designed to test faults in SoC. Furthermore, a clock chain logic which can eliminate the metastable state is realized to generate an enable signal for the OCC controller, and then, the test pattern is generated by automatic test pattern generation （ATPG） tools. Next, the scan test pattern is simulated by using the Synopsys tool and the correctness of the design is verified. The result shows that the design of an at-speed scan test in this paper is highly efficient for detecting timing-related defects. Finally, the 89.29% transition-delay fault coverage and the 94.50% stuck-at fault coverage are achieved, and it is successfully applied to an integrated circuit design.

On-Chip Built-in Jitter Measurement Circuit for PLL Based on Duty-Cycle Modulation Vernier Delay Line

Phase-locked loops (PLLs) are essential wherever a local event is synchronized with a periodic external event. They are utilized as on-chip clock frequency generators to synthesize a low skew and higher internal frequency clock from an external lower frequency signal and its characterization and measurement have recently been calling for more and more attention. In this paper, a built-in on-chip circuit for measuring jitter of PLL based on a duty cycle modulation vernier delay line is proposed and demonstrated. The circuit employs two delay lines to measure the timing difference and transform the difference signal into digital words. The vernier lines are composed of delay cells whose duty cycle can be adjusted by a feedback voltage. It enables the circuit to have a self calibration capability which eliminates the mismatch problem caused by the process variation.

Design and verification of on-chip debug circuit based on JTAG

An on-chip debug circuit based on Joint Test Action Group(JTAG)interface for L-digital signal processor(L-DSP)is proposed,which has debug functions such as storage resource access,central processing unit(CPU)pipeline control,hardware breakpoint/observation point,and parameter statistics.Compared with traditional debug mode,the proposed debug circuit completes direct transmission of data between peripherals and memory by adding data test-direct memory access(DT-DMA)module,which improves debug efficiency greatly.The proposed circuit was designed in a 0.18μm complementary metal-oxide-semiconductor(CMOS)process with an area of 167234.76μm~2 and a power consumption of 8.89 mW.And the proposed debug circuit and L-DSP were verified under a field programmable gate array(FPGA).Experimental results show that the proposed circuit has complete debug functions and the rate of DT-DMA for transferring debug data is three times faster than the CPU.

A new LFSR based high-frequency test method for RSFQ circuit

Rapid single flux quantum(RSFQ)circuits have the advantages of high speed and low power consumption.The typical frequency of the RSFQ circuits is tens of GHz.Therefore,it is necessary to reliably test the highfrequency performance of RSFQ circuits simply and effectively.This paper proposes a new on-chip highfrequency testing method,which uses pseudo-random sequences generated by linear feedback shift register(LFSR)as the test vectors,and the output shift registers(SRs)to store the last piece of high-frequency testing result and read out it at low-frequency.Unlike the traditional high-frequency demonstration method of using the Input/Output SRs,our testing system can automatically generate a large number of test vectors to test the circuit at high frequency at low cost,making the whole high-frequency demonstration more reliable and convincing.On the other hand,this method is also a feasible and straightforward on-chip high-frequency test method for various RSFQ circuits.This work verified the proposed method,and the highest test frequency can reach 54 GHz while the circuit shows good operating margins.