CCD charge-splitter adjustment by static charge gradient
A charge splitter for separating an incoming charge packet into two outgoing packets while the charge is in a static state, i.e., not while it is flowing down a channel or over a barrier. A splitting gate may have a biasing charge impressed upon it, such as via the application of voltage or current sources to opposite ends thereof, applying a bias to a semiconductor body portion of the gate structure, or by physically separate the splitting gate into multiple sections that each have different applied voltages or currents When discharge barrier gates are operated, different amounts of charge will thus flow to different output storage gates.
1. An apparatus for splitting an input charge in a charge coupled device comprising:
a splitting gate, for transferring an input charge, or storing an input charge, according to the state of an applied control clock signal;
a gradient applicator, for developing a charge gradient across the splitting gate at least while the input charge is stored therein in a static mode; and
a control signal generator, for applying a clock signal to the splitting gate to operate it between the static mode wherein charge is held therein, and a transfer mode, wherein charge is transferred.
2. An apparatus as in claim 1 wherein the splitting gate is formed of a conductive material over a channel.
3. An apparatus as in claim 2 wherein the channel is split into at least two output channels adjacent the splitting gate.
4. An apparatus as in claim 1 additionally comprising:
an output barrier gate, arranged to control charge exiting the splitting gate in the transfer mode.
5. An apparatus as in claim 1 additionally comprising:
an input barrier gate, arranged to control charge entering the splitting gate in the transfer mode.
6. An apparatus as in claim 1 additionally comprising:
at least two biasing voltage sources, applied to portions of the splitting gate, to develop the charge gradient.
7. An apparatus as in claim 1 additionally comprising:
at least two biasing current sources, applied to portions of the splitting gate, to develop the charge gradient.
8. An apparatus as in claim 1 additionally comprising:
at least two voltage sources, connected to a semiconductor body portion of the splitting gate.
9. An apparatus as in claim 1 wherein the splitting gate is formed of two or more sections, each having a high state voltage applied to cause a gradient to be developed across at least one splitting gate section.
10. An apparatus as in claim 9 wherein the splitting gate is formed of three adjacent sections, including a main section and two outlying sections, and the high stage voltage difference is applied to the outlying sections.