Patent ID: 6614286
Filing Date: 2003-09-02
Classification: G06G

Abstract:
An auto-ranging current integration circuit, comprising:an operational amplifier having its inverting input connected to receive an input current to be integrated, a first integration capacitor connected between said op amp's output and inverting input, said op amp and said integration capacitor arranged such that said input current is integrated on said first integration capacitor, one or more additional integration capacitors, one or more integration switches, each of which is closed and thereby provides a low resistance conductive path in response to a respective control signal applied to a control input, each of said integration switches connected in series with a respective one of said additional integration capacitors between said op amp's output and inverting input, and a control circuit which provides said control signals to said integration switches, said control circuit arranged to provide a control signal to close one of said integration switches and thereby connect an additional one of said integration capacitors between said op amp's output and inverting input whenever said op amp's output exceeds a reference voltage but before it becomes saturated, such that said current integration circuit's integration gain is automatically varied to prevent output saturation as the op amp output increases in response to an input current applied to said op amp's inverting input.