Multiplying circuit with pulse duration control means

Claim 1

A multiplying circuit comprising a pulse generator, having input and output terminals, for generating an electrical signal, T3, at said output terminal when a voltage above a reference voltage level is at said input terminal, a capacitor, having first and second terminals, coupled to said input terminal of said generating means at said first terminal and to said reference voltage level at said second terminal, a diode, having anode and cathode electrodes, coupled to said capacitor first terminal at said cathode electrode and to said reference voltage level at said anode electrode, said diode preventing said capacitor from being charged to a voltage below said reference voltage level, a first constant current source having an output current I1, a second constant current source having an output current I2 coupled to said capacitor first terminal, and switching means, having input, output and switching terminals, coupled to said first current source at said input terminal and to said capacitor first terminal at said output terminal, to apply said current I1 to said capacitor when an electrical pulse signal T1 is at said switching terminal, said capacitor being charged by current I3 I1-I2 for the duration of pulse T1 and thereafter by current I2, the voltage on said capacitor, when a potential above said reference voltage level, causing the generation of pulse T3 at the output of said pulse generating means, the relation between pulse T3 and T1 being substantially T3 (I1 . T1)/I2