Patent ID: 8400545

Claim:
An amplification circuit that amplifies the difference between a first signal and a second signal, comprising: a first capacitor connected between a first node and a second node; a second capacitor connected between a third node and a fourth node; an input circuit receiving said first signal and said second signal and connecting a selected one of said first signal or said second signal to said first node; a first switch circuit having an ON state connecting said second node to a reference voltage and an OFF state isolating said second node from the reference voltage; a second switch circuit having an ON state connecting said second node to said third node and an OFF state isolating said second node from said third node; a current supply circuit supplying current to said fourth node whereby a voltage at said third node will approach said reference voltage; a second capacitor discharge circuit selectively discharging said second capacitor; and wherein said amplification circuit operates in an initial phase wherein said second capacitor discharge circuit discharges the charge in said second capacitor, an integration phase including a first signal accumulation operation wherein said first switch circuit is in said ON state, said second switch circuit is in said OFF state and said input circuit inputs said first signal to said first node, and a second signal accumulation operation wherein said first switch circuit is in said OFF state, said second switch circuit is in said ON state and said input circuit inputs said second signal to said first node, following said first signal accumulation operation, repeated a number of times corresponding to an amplification factor.