DC offset correction in an antenna aperture
A method and apparatus for DC offset correction in an antenna aperture are described. In one embodiment, the antenna comprises: an array of antenna elements having liquid crystal (LC); drive circuitry coupled to the array and having a plurality of drivers, each driver of the plurality of drivers coupled to an antenna element of the array and operable to apply a drive voltage to the antenna element; and voltage correction logic coupled to the drive circuitry adjust drive voltages to compensate for an offset between a first magnitude of a first voltage applied to the LC of each antenna element during a first interval of drive polarity and a second magnitude of a second voltage applied to the LC of said each antenna element during a second interval of drive polarity opposite the drive polarity of the first interval.
1. A method comprising:
(a) driving an element of an antenna aperture in an antenna, the antenna aperture having a plurality of radio-frequency (RF) radiating antenna elements;
(b) observing, with respect to the element, a difference in optical transmission between positive and negative frames when monitoring the element;
(c) adjusting a common voltage on the element to null flicker;
(d) creating new positive and negative frame voltages by adjusting old positive and negative frame voltages using the adjusted common voltage;
(e) applying the new positive and negative frame voltages to the element;
(f) checking for flicker with the element being driven by the new positive and negative frame voltages; and
(g) using the new positive and negative frame voltages if an amount of flicker is below a threshold.
2. The method defined in claim 1 wherein the element comprises a first test element and is driven at a first gray level.
3. The method defined in claim 2 further comprising repeating operations (a)-(g) for a second gray level, the second gray level not being the same as the first gray level.
4. The method defined in claim 3 further comprising repeating operations (a)-(g) for a plurality of gray levels other than the first gray level.
5. The method defined in claim 1 wherein the element comprises a first test element, and further comprising interpolating correction values obtained from the first test element and a second test element to obtain a correction value for use with an antenna element located between the first and second test elements.
6. The method defined in claim 1 wherein the threshold is a state in which flicker does not exist with the element.
7. A method comprising:
obtaining an optical response of an antenna element of an antenna aperture; and
correcting a difference between the positive and negative frames based on the obtained optical response of the antenna element.
8. The method defined in claim 7 wherein the optical response is measured using a test optical structure on the antenna aperture.
9. The method defined in claim 7 further comprising adjusting a common voltage on the antenna element to null flicker.
10. The method defined in claim 7 further comprising:
creating new positive and negative frame voltages by adjusting old positive and negative frame voltages using a common voltage; and
applying the new positive and negative frame voltages to the antenna element.
11. The method defined in claim 10 further comprising:
checking for flicker with the antenna element being driven by the new positive and negative frame voltages; and
using the new positive and negative frame voltages if an amount of flicker is below a threshold.