Broadband amplifiers implemented in complementary metal-oxide semiconductor technology offer a low-cost solution as gain elements for wideband communication systems. These components must maintain an acceptable target performance for a wide range of temperatures. We present experimental results for the gain, reflection coefficients, and group delay of a broadband amplifier operating from 2to14GHz in the temperature range of 25–125°C. The high-frequency power gain drops by approximately 0.37dB every 10°C of temperature increase, the maximum input and output refection coefficients change by less than 0.1dB∕10°C, and the change in the input-to-output group delay is negligible over the measured temperature range. The amplifier was simulated using temperature-dependent measurement-based models for the transistors, capacitors, and resistors and a single-temperature electromagnetic-simulation-based model for the inductors and interconnections. Simulated gain degradation is 0.22dB∕10°C, which suggests that the temperature effects on the inductors and interconnections lines are very important; however, temperature-dependent simulation is not a standard feature of electromagnetic (EM) simulators. It is thus important to include temperature effects when developing models based on EM simulations. Our results suggest that the key element to be considered is the conductor’s resistivity increase with temperature.