Abstract: A device for heating or cooling air, has a housing with an inlet and an outer, as well as an inlet plenum and an outlet plenum for passing air through the housing. A heat sink defines a plurality of air passages between the inlet and outlet and fans in the housing move air through the inlet plenum, across the passages, into the outlet plenum. A plurality of Peltier modules in the housing each have one surface in heat transfer contact with the heat sink and an opposite surface in contact with a heat transfer circuit such as a flow or water in pipes, for cooling or heating the opposite surfaces. A purely relay-based, or PWM-based power circuit is connected to the modules for powering the modules and fans to cool or heat the heat sink.

Abstract: In one embodiment, an output transistor and a bias compensation device are placed in proximity to each other on the same package substrate. The bias compensation device is electrically isolated but thermally coupled to the output transistor, and is configured to provide a output signal for adjusting bias to the output transistor.