Patent ID: 7339180

Claim:
A particle beam current measuring device comprising: a Faraday cup; an integrator circuit in current receiving relation to the Faraday cup; a programmable gain amplifier connected in voltage receiving relation to the integrator circuit and in voltage supplying relation to an analog-to-digital converter; a first trigger generation circuit in trigger supplying relation to the analog-to-digital converter, arranged to supply a first trigger signal and a second trigger signal separated by a selected time interval; a plurality of data registers including at least a first data register and a second data register, the first data register arranged to receive a first digital voltage level when the analog-to-digital converter receives the first trigger signal, the second data register arranged to receive a second digital voltage level when the analog-to-digital converter receives the second trigger signal; a third data register connected to the first data register and the second data register by logic which operates to subtract the first data register from the second data register, and to enter a difference value into the third data register; and FIFO memory in data receiving relation to said third data register.