Impact of Radiation-Induced Single-Event Transients on High Resolution Time to Digital Converter
The paper presents the analysis of radiation-induced Single-Event Transients (SET) in Delay-Locked Loop (DLL) and its impact in the digital output of Time-to-Digital Converter (TDC). The performance of the TDC such as Differential Non-Linearity (DNL),Integral Non- Linearity (INL), resolution etc. are degraded due propagation of the SET from the DLL. The use of improved pseudo differential current-starved delay cell structure in the Voltage Controlled Delay Line (VCDL) in DLL reduces the impact of radiation- induced SET in DLL, and enhances the robustness of DLL based TDC. This effort represents the first of its kind SET analysis on a DLL based TDC. The proposed DLL based TDC is designed in the AMS 180 nm CMOS technology and simulations show that the number of missing pulses on a SET strike in the modified pseudo differential delay cell is reduced to 50% than compared the conventional architectures.
Single Event Transients in Logic Circuits—Load and Propagation Induced Pulse Broadening
The generation and propagation of single event transients (SET) in logic gate chains is studied and modeled. Regarding SET generation, we investigate the dependence of the generated SET pulse width on the struck node capacitance. Rising node capacitance may lead to amplified pulse width, indicating that increasing load capacitance alone is not an option for radiation hardening. SET propagation in logic chains is also studied, and it is shown that significant broadening or attenuation of the propagated transient pulse width may be observed. It is shown that the chain design (propagation delay of high to low and low to high transitions) has a major impact on broadening or attenuation of the propagated transient pulse. For the first time a suitable model for SET broadening is provided.
A time-to-amplitude converter with constant fraction timing discriminators for short time interval measurements
Abstract The construction and the performance of a time-to-amplitude converter equipped with constant fraction discriminators is described. The TAC consists of digital and analog parts which are constructed on two printed circuit boards, both of which are located in a single width NIM module. The dead time of the TAC for a start pulse which is not followed by a stop pulse within the time range of the device (∼ 100 ns) is only ∼ 100 ns, which enables one to avoid counting rate saturation even with a high random input signal rate. The differential and integral nonlinearities of the TAC are better than ± 1.5% and 0.0.5%, respectively. The resolution for input timing pulses of constant shape is 20 ps (fwhm), and less than 10 ps (fwhm) with a modification in the digital part. The walk error of the constant fraction timing discriminators is presented and various parameters affecting it are discussed. The effect of the various disturbances in linearity caused by the fast ECL logic and their minimization are also discussed. The time-to-amplitude converter has been used in positron lifetime studies and for laser range finding.