In this paper the effect of temperature transient on the large-signal properties and frequency chirping of 94 GHz pulsed silicon Double-Drift Region (DDR) Impact Avalanche Transit Time (IMPATT) device is investigated. A transient thermal model and a large-signal simulation method based on non-sinusoidal voltage excitation have been developed by the authors' to study the effect temperature transients on the large-signal characteristics and frequency chirping in pulsed Si DDR IMPATTs. Results show that the device is capable of delivering a peak pulsed power output of 17.5 W with 12.8% efficiency when the voltage modulation is 60%. The maximum junction temperature rise is 350.2 K for a peak pulsed bias current of 6.79 A with 100 ns pulsewidth and 0.5 percent duty cycle; whereas the chirp bandwidth is 8.3 GHz. © 2012 IEEE.