Circuits for generating voltage references are common in electronics. For example, these circuits are used in analog-to-digital converters, which convert an analog signal into its digital representation by comparing analog input signals against one or more voltage references provided by those circuits. In many applications, the speed and accuracy of such voltage references are very important. The speed of the voltage references is related to the physical properties of the devices in the circuit. The accuracy of the voltage reference is directly related to the circuit's ability to trim the full-scale voltage output. The present disclosure describes a fast and efficient reference buffer with a wide trim range which is particular suitable for submicron processes and high speed applications. The reference buffer comprises a plurality of diode-connected transistors, which can be selected to turn on or off using a controller to provide a wide trim range.