Self-biasing MOS Reference Current Sources Insensitive to Supply Voltage and Temperature

Abstract

This paper describes three types of self-biasing MOS reference current sources insensitive to supply voltage and temperature. (i) The first one is a Gunma University (GU) reference current source, based on our previously proposed temperature-insensitive MOS reference current source. This time, a simple startup circuit is investigated. Since this circuit has two stable states, it is necessary to use a startup circuit to initially operate it in the correct stable state. We have improved the startup circuit with a simple technique, which can turn off after the normal operation starts. This startup circuit is also used for the other two self-biasing MOS current sources. The impact of NMOS threshold voltage variation on circuit performance is verified by simulation. (ii) The second one is a peaking current source (or a Nagata current source) with self-biasing configuration. Due to the self-biasing configuration, the supply voltage insensitivity range is widened. Also, simulations show that careful designing MOSFET size and resistor value can realize temperature insensitivity of the output current. (iii) The third one is a Widlar current source with self-biasing configuration, which improves the supply voltage insensitivity of the output current. We also detail some additional circuits that boost its temperature insensitivity.