Massively parallel three dimensional per pixel single slope analog to digital converter

1. A single slope analog to digital converter (ADC) comprising:

a comparator having a positive input and a negative input and a comparator output, the comparator being contained in a first layer;

a counter coupled to the comparator output and contained in a second layer formed by a non-ITAR compliant process and that is below the first level;

wherein the counter is electrically coupled to the comparator with a through silicon via.

2. The single slope ADC of claim 1 , wherein the first layer and the second level are formed using different semiconductor process nodes.

3. The single slope ADC of claim 2 , wherein the first level is formed by an ITAR 180 nm or 90 nm process node.

4. The single slope ADC of claim 3 , wherein the second level is formed by a non-ITAR 65 nm or lower process node.

5. The single slope ADC of claim 1 , further including an integration capacitor coupled to the positive input of the comparator and included in the first layer.

6. The single slope ADC of claim 1 , wherein the first layer is physically connected to the second layer by a direct wafer bond formed by direct bond integration.

7. A method of forming a single slope analog to digital converter (ADC) comprising:

forming a comparator having a positive input and a negative input and a comparator output in a first layer;

forming a counter coupled to the comparator output and contained in a second layer; and

electrically coupling the counter and the comparator with a through silicon via;

wherein the first layer and the second level are formed using different semiconductor processing processes.

8. The method of claim 7 , wherein the first level is formed by an ITAR 180 nm or 90 nm process.

9. The method of claim 8 , wherein the second level is formed by an non-ITAR 65 nm or lower process.

10. The method of claim 7 , further including forming an integration capacitor coupled to an input of the comparator in the first layer.

11. The method of claim 7 , further comprising physically connecting the first layer to the second layer by a direct wafer bond formed by direct bond integration.

12. An image detector comprising:

an array of detector unit cells including a plurality of unit cells; and

a plurality of single slope analog to digital converters (SSADCs), each of the plurality of SSADCs coupled to an output of a different one of the unit cells, wherein each of the plurality of SSADCs includes:

a comparator having a positive input and a negative input and a comparator output, the comparator being contained in a first layer; and

a counter coupled to the comparator output and contained in a second layer;

wherein the counter is electrically coupled to the comparator with a through silicon via.

13. The image detector of claim 12 , wherein the first layer and the second level are formed using different semiconductor process nodes.

14. The image detector of claim 13 , wherein the first level is formed by an ITAR 180 nm or 90 nm process node.

15. The image detector of claim 14 , wherein the second level is formed by a non-ITAR 65 nm or lower process node.

16. The image detector of claim 12 , wherein each of the plurality of SSADCs further includes an integration capacitor coupled to the positive input of the comparator and included in the first layer.

17. The image detector of claim 12 , wherein the first layer is physically connected to the second layer by a direct wafer bond formed by direct bond integration.

18. A method of forming a single slope analog to digital converter (ADC) comprising:

forming a comparator having a positive input and a negative input and a comparator output in a first layer;

forming a counter coupled to the comparator output and contained in a second layer;

electrically coupling the counter and the comparator with a through silicon via; and

physically connecting the first layer to the second layer by a direct wafer bond formed by direct bond integration.