Reference-less level-crossing adc with a bump-based adaptive-bias comparator

An analog to digital converter (ADC) circuit for a neural interface, wherein the ADC circuit is configured to receive a differential input signal comprising a first signal and a second signal, and wherein the ADC circuit comprises:

• a first comparator circuit and a second comparator circuit, wherein an inverting input of the first comparator circuit and a non-inverting input of the second comparator circuit are connected to a common mode voltage of the first signal and the second signal;
• a first switching circuit configured to receive the first signal and to provide a modified first signal via a first voltage line to a non-inverting input of the first comparator circuit;
• a second switching circuit configured to receive the second signal as an input and to provide a modified second signal via a second voltage line to an inverting input of the second comparator circuit;
• and
• a control circuit, wherein an output of the first comparator circuit and the second comparator circuit is connected as input to the control circuit, and an output of the second comparator circuit is connected as input to the control circuit;
• wherein the first switching circuit comprises a plurality of first capacitor pairs, and the second switching circuit comprises a plurality of second capacitor pairs, wherein the first and the second capacitor pairs are respectively arranged along the first voltage line and the second voltage line, and are respectively connected with a common node to the first voltage line and the second voltage line;
• and
• wherein the control circuit is configured to set at least one capacitor state of the first capacitor pairs and at least one capacitor state of the second capacitors pairs based on the output of the first comparator circuit and based on the output of the second comparator circuit.