Analog-to-digital converter having an excellent signal-to-noise ratio for small signals

An oversampled analog-to-digital converter comprising:

• a delta-sigma modulator having at least an analog signal input terminal, a first adder having a first input connected to the analog signal input terminal and a second input, an analog integrator connected to receive an output of the first adder, a second adder having a first input connected to an output of the integrator and a second input, and a comparator having an input coupled to receive an output of the second adder and operating to generate a digital signal at a given sampling frequency, a flipflop connected to receive the digital signal, and an inverter connected to an output of the flipflop and an output connected to the second input of the first adder;
• and
• a noise generator including a one-bit white noise generator connected to receive the digital signal outputted from the comparator for generating a one-bit white noise signal, and means coupled to the one-bit white noise generator for outputting a signal indicative of a difference between values of two white noise signals at two continuous sampling points, this difference signal being added to the second input of the second adder, wherein said digital signal is generated without subtracting said one-bit white noise signal therefrom.

An oversampled analog-to-digital converter comprising:

• a first-order predicate primary noise shaping analog-to-digital conversion circuit having at least an analog signal input terminal, a first adder having a first input connected to the analog signal input terminal and a second input, an analog integrator connected to receive an output of the first adder, a second adder having a first input connected to an output of the integrator and a second input, and a comparator having an input coupled to receive an output of the second adder and operating to generate a digital signal at a given sampling frequency, a flipflop connected to receive the digital signal, an inverter connected to an output of the flipflop, and a prediction circuit connected to receive an output of the inverter and an output connected to the second input of the first adder;
• and
• a noise generator including a one-bit white noise generator connected to receive the digital signal outputted from the comparator for generating a one-bit white noise signal, and means coupled to the one-bit white noise generator for outputting a signal indicative of a difference between values of two white noise signals at two continuous sampling points, this difference signal being added to the second input of the second adder, wherein said digital signal is generated without subtracting said one-bit white noise signal therefrom.

An oversampled analog-to-digital converter comprising:

• a delta modulator having at least an analog signal input terminal, an adder having a first input connected to the analog signal input terminal and a second input, and a comparator having an input coupled to receive an output of the adder and operating to generate a digital signal at a given sampling frequency, a flipflop connected to receive the digital signal, and a prediction circuit connected to receive an output of the flipflop and an output connected to the second input of the adder;
• and
• a noise generator including a one-bit white noise generator connected to receive the digital signal outputted from the comparator for generating a one-bit white noise signal, and means coupled to the one-bit white noise generator for outputting a signal indicative of a difference between values of two white noise signals at two continuous sampling points, this difference signal being added to the input of the comparator, wherein said digital signal is generated without subtracting said one-bit white noise signal therefrom.