This paper presents a design of an advanced pulse-train time amplifier (A-PTTA) that utilizes an active off-state time control to minimize the skew error and conversion rate in the radiation environments. Three D-flip-flops are employed to provide an overlap code (O-code), determining whether overlap occurs between the first input pulse and subsequent pulses. The output of the time amplifier is determined by selecting one of the delay chains based on the O-code. The proposed A-PTTA was verified using an electronic design automation tool, demonstrating the maximum improvement of 70% in conversion time. The proposed circuit was fabricated using general-purpose $0.18\mu \mathrm{m}$ CMOS technology, and the test results will be discussed at the conference.