Abstract: A circuit for generating a signal comprising a first transistor having a drain, a gate and a source. A second transistor having a drain, a source and a gate coupled to the gate of the first transistor to form a current mirror. A current source coupled to the source of the first transistor. A diode-connected transistor having a drain coupled to the source of the second transistor, a source and a gate that forms an output. A variable resistor having a first terminal coupled to the source of diode-connected transistor and a second terminal. A capacitor coupled to the second terminal of the variable resistor.

Abstract: A system for current mode sample and hold, comprising a first PMOS transistor configured to generate a current to be sampled. A diode-connected NMOS transistor coupled to the first PMOS transistor and configured to receive the current. A switch coupled to the diode-connected NMOS transistor and configured to sample a gate-source voltage of the diode-connected NMOS transistor. A capacitor coupled to the switch and configured to stored the gate-source voltage of the diode-connected NMOS transistor. A second NMOS transistor coupled to the capacitor and configured to generate a current equal to the sampled current value.

Abstract: This disclosure provides systems and methods for decoupling the mechanical drive systems of image scanners from the exposure system. A light source, such as an array of light-emitting diodes (LEDs), may be modulated in order to maintain a constant exposure for each scan-line, regardless of the document velocity. Accordingly, the present systems and methods allow for continuous document scanning at varying speeds. An automatic document feeder may dynamically adjust the velocity of a document without negatively impacting the exposure of the image scan. As the velocity of the document is changed, the modulation rate of the light source may be adjusted to maintain a constant exposure.

Abstract: A driver controller comprising a state machine for controlling transitions between a plurality of states. An output switch for providing a low impedance path to ground during transition periods. An output stage for decoupling output signal from driver amplifier during the transition periods.