Abstract: An extended range of frequency synthesiser responsive to a number of different input frequencies to provide multiples of those input frequencies as its final outputs includes a phase locked loop having an output frequency range containing a multiple of each of the final output frequencies; and a pre-divider circuit for dividing the input frequencies by a first predetermined number before submission to said phase locked loop and a post divider circuit for dividing the phase locked loop output by a second predetermined number to obtain the final output while operating the phase locked loop in the output frequency range.

Abstract: An input protection device is provided for protecting a circuit structure which is coupled to a first node, the device comprising a first lightly-doped region of P-type material with a lightly doped well of N-type material formed in it. Two regions of heavily doped N-type and P-type material, which are electrically connected to the first node, are formed in the well of N-type material. A third heavily doped region of N type material is formed in the first lightly-doped region of P-type material and is electrically connected to a reference node. In a first aspect of this invention, the third heavily doped region of N type material is formed in a second well of N-type material, which in turn is formed in the first lightly-doped region of P-type material. In this first aspect of the invention a further region of heavily doped P-type material is formed in the second well of N-type material, this further region of heavily doped P-type material being electrically connected to the reference node.