Analog-to-digital converter circuit and method for analog-to-digital conversion

An analog-to-digital converter circuit having

• an input for receiving at least a first analog signal level,
• a ramp generator adapted to provide a ramp signal having a constant and adjustable starting level which splits into a first section which is rising and a second section which is falling concurrently to the first section's rising, wherein the starting level lies within an input range of the analog-to-digital converter circuit,
• a comparison unit which is coupled by its first input to the input of the analog-to-digital converter circuit and is coupled by its second input in a switchable manner to the ramp generator,
• a counter which is coupled to a control unit, and
• the control unit which is coupled to an output of the comparison unit,
• wherein the control unit is prepared to enable the counter depending on a comparison of the ramp signal with at least the first analog signal level and to determine a digital value as a function of a count of the counter reached at an intersection point of the ramp signal with at least the first analog signal level,
• wherein the ramp generator comprises a first capacitor, a second capacitor, a first current generating unit and a second current generating unit,
• wherein the first capacitor is coupled in a switchable manner under control of the control unit to an output of the first current generating unit, and the second capacitor is coupled in a switchable manner under control of the control unit to an output of the second current generating unit,
• wherein the first capacitor is connected in a switchable manner under control of the control unit to the second capacitor,
• wherein the first current generating unit is configured to provide a positive charging current having an adjustable level at its output in order to generate the first section of the ramp signal in cooperation with the first capacitor, and
• wherein the second current generating unit is configured to provide a negative charging current having an adjustable level at its output in order to generate the second section of the ramp signal in cooperation with the second capacitor.