Analog-to-digital converter with error checking and correction circuits

An analog-to-digital converter comprising:

• a plurality of voltage comparators for providing different output signals as a function of the voltage amplitude of an analog input signal;
• means for decoding said output signals and providing a digital word signal corresponding to the voltage amplitude level of said analog input signal;
• preconditioning means for forming intermediate signals representing different EXCLUSIVE-OR combinations of said output signals, said intermediate signals characterized by repeating waveform patterns over the operating range of said converter which are different in the case of each intermediate signal;
• and
• detection means for providing an error signal indicative of when combinations of said intermediate signals correspond to combinations which should not occur during operation of said converter.

In a flash analog-to-digital converter which includes a plurality of separate voltage comparators, a method for checking for errors in the output signals produced by said comparators, comprising the steps of:

• generating a set of intermediate signals which represent different EXCLUSIVE-OR combinations of said output signals of said comparators and which are characterized by repeating waveform patterns in which said intermediate signals change to the same logic state at different voltage levels and all change to the complementary logic state at the same voltage level;
• processing said intermediate signals through a logic network in order to detect when said intermediate signals are present in combinations of logic states which should not occur in accordance with the proper operation of said comparators;
• and
• providing an error signal indicative of the occurrence of such combinations.

An analog-to-digital converter, comprising:

• a plurality of comparators for generating output signals as a function of the amplitude of an analog signal voltage and each of which includes a set of differential amplifiers, each of said amplifiers adapted to receive as inputs said analog signal and a different reference voltage and connected to a pair of common differential output conductors with the output terminals of alternate amplifiers being connected to opposite conductors;
• a decoder for receiving said comparator output signals and generating a digital word signal corresponding to the voltage amplitude of said analog input signal;
• a preconditioning circuit for generating a set of intermediate waveforms representing EXCLUSIVE-OR combinations of said comparator output signals which are characterized by different repeating waveform patterns;
• and
• a detection circuit for generating an error signal when said intermediate signals form combinations which should not occur in accordance with the proper operation of said converter.