US 4,057,796 AGranted

Analog-digital converter

AssigneeU.S. Philips Corporation

InventorsAbraham Hoogendoorn, Robert Emile Johan VAN DE Grift, Theodorus Jozef VAN Kessel

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Abstract

An analog-digital converter in which a capacitor is charged or discharged by a reference current with the aid of transistor switches, a continuous current flows through the capacitor which is determined by an input difference voltage. One side of the capacitor is connected via a comparator to a flip-flop, to which flip-flop a clock signal is applied and which flip-flop drives the transistor switches. The other side of the capacitor is connected to the first input of a differential amplifier, which differential amplifier forms part of a negative feedback loop which maintains the voltage at the first input of the differential amplifier equal to the voltage which is applied to the second input of the differential amplifier.

Claims14

Dependent claims

An analog-to-digital converter for converting an input analog signal comprising

a comparator having first and second inputs and an output;
a differential amplifier having first and second inputs and an output;
a capacitor having a first electrode connected to said first input of said comparator, and a second electrode to said first input of said differential amplifier;
a flip-flop, having an input connected to the output of said comparator, and an output representing the digitized form of said input analog signal;
means connected to the output of said differential amplifier for controlling the current through said capacitor;
a clock generator, for applying a clock signal to said flip-flop;
a first transistor switch controlled by said flip-flop and connected to said first electrode of said capacitor;
and
a second transistor switch connected to the second electrode of said capacitor and driven in phase opposition to said fist transistor switch by the output signal of said flip-flop.

6 more elements

Dependencies are inferred from the claim text.