Input protection circuits for integrated circuit devices

An imput of a CMOS integrated circuit device is protected from excessive voltage swings at an input terminal by a protection circuit which comprises two series-connected protective stages between the device input terminal and the input. Each protective stage comprises a current-limiting series resistor and clamping diodes connected to the supply voltages of the device. The two stages enable the series resistance of the protection circuit to be much lower than that required for a single stage diode clamping arrangement, this being particularly advantageous if the device is an analog-to-digital converter for converting to digital values analog voltages present at the input terminal.