A 1.7-in, 33-Mpixel, 120-frames/s CMOS Image Sensor With Depletion-Mode MOS Capacitor-Based 14-b Two-Stage Cyclic A/D Converters

A 1.7-in, 33-Mpixel, 120-frames/s, 14-bit CMOS image sensor has been developed. The 7936 (H) × 4412 (V) pixel CMOS image sensor, which uses 14-b depletion-mode MOS (DMOS) capacitor-based two-stage cyclic A/D converters (ADCs) and 64 parallel scalable low-voltage signaling output ports, operates at a data rate of 63.8 Gb/s. DMOS capacitors have a high capacitance density, but it is difficult to achieve high bit resolutions in ADCs with these capacitors because their capacitance depends on the applied voltage. Column-parallel two-stage cyclic ADCs overcome this difficulty using a split-sampling DMOS capacitors architecture. The two-stage cyclic ADC with the DMOS capacitors at a 6.4-μm column pitch exhibited a differential nonlinearity of 0.95/-0.80 least significant bit (LSB); the integral nonlinearity was 2.57/-28.27 LSB at a 14-b resolution. The CMOS image sensor implemented with a 90-/65-nm technology exhibited a sensitivity of 5.22 V/lx·s and a random noise of 3.6 e
^-
_rms
with a gain of 3.3 at 120 frames/s while dissipating 3.2 W.