Abstract: Systems and methods for the detection of motions of a pointed object upon a digitizing surface such as a touchpad is disclosed. The motions will be detected and converted to digital codes representing the absolute coordinates of the pointed objects upon the touchpad. The absolute coordinates will be translated into a stroke signal to interpret a single tap, a double tap, and a tap and drag of the pointed object on the touchpad. Further, multiple sets of absolute coordinates will be translated into a relative motion code that will contain the speed and direction of the pointed object as it is moved across the touchpad. The absolute coordinates will be interpreted by an autocursor controller to determine if the pointed object has transited between a workzone and an edgezone of the touchpad. If the pointed object is in the edgezone, a predefined relative motion code will be transmitted as an autocursor code.

Abstract: This invention describes a numeric intensive real-time software development system for programming low cost fixed point digital signal processors (DSP's) and other programmable devices in which code efficiency, ease of programming and code portability are maintained. DSP's being a generic math engine are proliferating into many areas, far beyond the traditional filtering applications. Numeric intensive is the most distinctive nature of the DSP software, and one of the biggest challenges in DSP software development is to implement complicated math algorithms in low cost fixed-point DSP's. The software development system describes an approach where low level assembly language is enhanced with high level syntax and further augmented with an enhance numeric handler for converting between numeric formats. Debug of the DSP programs is aided by the numeric format conversion and the use of high level syntax. The resulting program is written to a driver interface which facilitates porting code between different DSP's.

Abstract: A current reference circuit for use in a memory sense amplifier is described, which generates a mid-point current reference that is insensitive to fabrication process variations. This circuit is also robust enough to handle distinctly different levels of "0" and "1" sense currents without causing clipping of the mid-point reference current. Adequate sensing levels for the bit line sense amplifier are thus ensured.

Abstract: In this invention is described a CMOS buffer that reduces short circuit current in the output stage. The short circuit current is a result of current flowing between circuit bias and ground through the output transistors during switching transition. The reduction in shorting current is accomplished by driving the two CMOS output transistors of opposite type separately, and providing a turn off signal for one output transistor ahead of the turn on signal for the other transistor. Thus one transistor is turned off before the other transistor is turned on, reducing shorting between the two transistors. The on and off signal delay is controlled from unbalanced inverters connected separately to each input of the output transistors.

Abstract: A digitizing tablet has an improved operation for saving power. After an input device contacts the tablet surface, resistive sheets provide analog pen position signals to a sample/track and hold circuit. Once the signals are captured by the sample/track and hold, power is removed from the resistive sheets and digitization of the analog signals is performed. During an input waiting period, power is further conserved by removing power from the sample/track and hold and analog-to-digital converter, as a separate level detect circuit detects contact with the tablet surface by an input device.

Abstract: Systems and methods for the detection of motions of a pointed object upon a writing surface such as a touchpad are disclosed. The motions will be detected and converted in an analog-to-digital converter to digital codes representing the location of the pointed object upon the touchpad. The motion will be translated into a pen detect signal indicating the presence of the pointed object upon the touchpad. The digital codes will be filtered to minimize noise and formed into a filtered absolute coordinates digital code. The filtered absolute coordinate digital code and the pen detect signal will be converted to a touchpad-computer interface protocol and transferred to a computer system for further processing.

Abstract: Systems and methods for the detection of motions of a pointed object upon a writing surface such as a touchpad is disclosed. The motions will be detected and converted in a multiplexing analog-to-digital converter to digital codes representing the location of the pointed object and the pressure of the pointed object upon the touchpad. The location and the pressure will be translated into a pen detect signal indicating the presence of the pointed object upon the touchpad. The digital codes will be averaged to minimize noise created by vibrations and variations in the motions of the pointed object held by the human hand and formed into an absolute coordinate digital code. The absolute coordinate digital code, the pressure digital code, and the pen detect signal will be converted to a touchpad-computer interface protocol for transmission to a computer system for further processing.

Abstract: A method and means for the control of a cursor upon a display screen of a computer system by a pointed object such as a pen, stylus, or finger upon an electrical writing surface is disclosed. The method and means will allow the cursor to continue to scroll across the display screen in a fixed direction and at a fixed speed once the pointed object has transited from a workzone region to an edgezone region of the touchpad. Once the pointed object is in the edgezone region, the pointed object may be stopped. If a different direction or speed of movement of the cursor is desired, the pointed object can be moved in the new direction to establish the new direction and speed of movement of the cursor. The control of the cursor will return to the normal movement when the pointed object returns to the workzone from the edgezone.

Abstract: The present invention provides a voltage controlled oscillator with improved noise immunity and minimized variation due to manufacturing process, power supply and operating temperature changes. The voltage controlled oscillator consists of fully differential connected ring oscillator that includes a plurality of differentially connected delay elements. The ring oscillator responds to a control current signal for controlling the frequency of oscillation. A voltage to current converter converts the input tuning voltage to an output current for the controlling of the ring oscillator. The delay element consists of two source coupled P-channel transistors connected to a current source. The drains of the P-channel transistors are each connected to a voltage controlled impedance that changes the delay characteristics of the delay element in response to the input tuning voltage.

Abstract: A multiply/accumulate computation circuit is provided. The circuit will perform the multiplication of a first binary number that is a multiplicand and a second binary number that is a multiplier to produce a product. The product can be added or subtracted from a previous result. The product may be negated. The product may be multiplied by a factor of two. Or the product that is multiplied by the factor of two may be added or subtracted from the previous result. The multiplication is accomplished in a modified Radix 4 Booth's encoding and translation circuit to produce a set of partial products that are combined in a n operand adder to form a final result.

Abstract: A novel ring shaped emitter structure with an extrinsic base and base contact in the central portion of the ring is described. This structural configuration is useful for improving the performance of bipolar transistors used in BiCMOS integrated circuits with only minimal changes to conventional CMOS processing technology. A single additional mask is required to form the intrinsic base region of the transistor. The emitter is diffused from a polysilicon layer which also serves as the emitter contact. The polysilicon layer overlies a perimeter portion of an active region defined by an opening in a field oxide and rises up over the field oxide itself. The active emitter region then forms a ring along the perimeter of the active region. The extrinsic base is formed through an opening within the polysilicon layer representing a central portion of the active region.

Abstract: A system to transfer a serial digital data protocol between a controlling processor such as digital signal processor and a plurality of analog front-end devices is described. The system has a serial clock unit to generate a serial clock reference signal, a serial data control unit to create the serial data protocol, a serial clock transmission medium, a serial data transmission medium, and an analog front-end control unit. The serial digital data protocol has a start bit time, an address time, a read/write bit time, a first high impedance time, a serial data word time, a second high impedance time, and a stop bit time. A serial data word may be transferred either from the controlling processor to the analog front-end device or from the analog front-end device to the controlling processor dependent on the state at the read write bit time.