Abstract: An optical receiver is disclosed that exhibits an improved phase margin and substantially constant output in response to changes in operating conditions (e.g., temperature, process, etc.). In accordance with the illustrative embodiment, a common-mode feedback comparison is performed prior to conversion of the signal from single-ended to differential voltage. When the common-mode feedback comparison is performed in this way, there are fewer amplifiers in the signal path and the phase margin of the common-mode feedback loop is increased. In addition, as the common-mode feedback is performed at the first stage of the transimpedance amplifier, the gain response of the transimpedance amplifier remains substantially constant in response to changes in temperature, input current range, and for different integrated circuit fabrication processes.

Abstract: A multifunction portable electric room heater has an outer housing provided with an air inlet and air outlet and encloses a removable unit including a hollow base containing electrical power supply circuitry and supporting on its upper side a heating cartridge holder and a fan having an electrical motor connected for energization to the power supply circuitry. A heating cartridge carrying a PTC electric resistance heating element is removably inserted into the holder through registering slots in the housing wall and holder for heating the air circulated by fan through the holder and the heating cartridge from the air inlet to the air outlet. Cooperating electrical connectors are provided on the base and heating cartridge for detachably connecting the heating element to the power supply circuitry in the base.