Abstract: A mass air flow measurement circuit is disclosed which provides a digital output without using a separate analog to digital (A/D) converter. This air flow measurement circuit includes a bridge circuit, wherein voltage is supplied to the bridge to control current through one or more sense elements in order to keep the temperature and resistances of the sense elements constant and balance the bridge. An electrical comparator is used to sense the balance of the bridge, and the output of the comparator is applied to an input port of a microcomputer. The microcomputer generates a rectangular wave pulse width modulated (PWM) signal whose duty cycle is increased or decreased in response to the output of the comparator. The PWM signal is then amplified and applied to the bridge to balance the bridge. Mass air flow is then calculated by multiplying the duty cycle of the PWM signal by a proportionally constant.