| CPC H03M 3/464 (2013.01) [H03M 3/462 (2013.01); H03M 3/498 (2013.01)] | 29 Claims |
|
1. A circuit including a sigma-delta analog-to-digital converter circuit, comprising:
an integrator circuit configured to integrate a difference signal;
a single bit quantization circuit configured to quantize an output of the integrator circuit and generate a bit signal;
a feedback digital-to-analog converter circuit configured to generate an analog feedback signal from said bit signal; and
an input stage circuit comprising:
an input capacitor having a first terminal and further having a second terminal coupled to receive said analog feedback signal;
a first switch coupled between an analog current signal input and the first terminal of the input capacitor, said first switch actuated in response to a first clock signal;
a second switch coupled between the first terminal of the input capacitor and a reference node, said second switch actuated in response to a second clock signal;
wherein said first and second clock signals are non-overlapping;
a third switch coupled between the second terminal of the input capacitor and the reference node, said third switch actuated in response to the first clock signal; and
a fourth switch coupled between the second terminal of the input capacitor and an input of the integrator circuit to provide said difference signal, said fourth switch actuated in response to the second clock signal; and
wherein said analog current signal input is configured to receive a photocurrent generated by a photodiode, and further comprising a fifth switch coupled between the analog current signal input and the reference node, said fifth switch actuated to reset said photodiode.
|