Low level voltage pulse-converter

Claim 1

A converter for converting the differential of a pair of analog signals to a digital pulse, comprising: a switching capacitor; an input circuit comprising a differential amplifier for receiving said pair of analog signals and applying said differential signal to said switching capacitor to charge said switching capacitor to a charge level which is proportional to said differential signal; an output circuit connectable to said switching capacitor and including a constant current source for discharging said switching capacitor from its charge level to a selected low level during a discharging period; switching logic means connected to said input and output circuits for connecting said input and output circuits one at a time to said switching capacitor for charging said switching capacitor to its charge level and for discharging said switching capacitor to the selected low level, said switching logic means connecting said switching capacitor to said input circuit for sufficient time to reach said charge level and connecting said switching capacitor to said output circuit for a time longer than said discharging period, said switching logic means comprising a microprocessor, said input circuit including a first pair of switches controllable by said microprocessor for connection of said differential amplifier to said switching capacitor, said output circuit including a second pair of switches controllable by said microprocessor for discharging said switching capacitor, operation of each pair of said first and second pair of switches occurring substantially simultaneously; and pulse generating means connected to said output circuit for generating a digital pulse having a duration equaling said discharging period.