Abstract: A frequency-divider circuit performs a division operation using a divisor that can include a fraction. In one such embodiment, a first divider module includes a divider circuit that operates to divide the frequency of an input clock signal and a phase-quadrature circuit. The first divider module generates a first-divider-output signal having periodic signals with regular phase displacement therebetween and a common period that is an integer multiple of the clock signal. Using this first-divider-output signal, a second divider module performs another divide operation and is clocked as a function of a delay effected by at least one of the periodic signals. The present invention is useful in a wide variety of applications including applications having a high frequency clock source that cannot tolerate excessive loading or jitter attributable to a divider circuit.

Abstract: A low power LVDS driver includes a switchable current module, a source termination circuit, a transistor section, and a load current source. The switchable current module is operably coupled to produce a first current when a differential input signal is in a first state and to produce a second current when the differential input signal is in a second state. The source termination circuit is operably coupled in parallel with a load. The transistor section is operably coupled to receive the first and second currents from the switchable current module via at least one of the source termination circuit and the load, wherein the transistor section produces an LVDS output signal based on the first and second currents, the differential input signal, and the source termination circuit. The load current source is operably coupled to sink the first and second currents from the transistor section.

Abstract: The invention relates to a buffer solution for suspending animal or human cells and for dissolving biologically active molecules in order to introduce said biologically active molecules into the cells using an electric current and to a method for introducing biologically active molecules into animal or human cells using an electric current and a buffer solution. The inventive buffer solution has a buffering capacity of at least 20 mmol*I?1*pH?1 and an ionic strength of at least 200 mmol*I?1 during a change to the pH value from pH 7 to pH 8 and at a temperature of 25° C. The use of a buffer solution of this type in the corresponding method allows biologically active molecules to be introduced into animal and human cells with a high degree of transfection efficiency and at the same time a low cell mortality. Different cell types, in particular dormant and actively dividing cells of low activity, can be successfully transfected in said buffer solution.

Abstract: Described are high-speed differential flip-flops. A flip-flop in accordance with one embodiment incorporates some combinational logic, eliminating the need for separate combinational logic when the flip-flop is employed in certain circuit configurations. A flip-flop in accordance with another embodiment includes differential input and output stages, each of which includes a transistor connected across its differential output terminals. The transistors are clocked to short the differential output terminals between expressions of logic levels, thereby limiting the maximum amount of voltage swing required to express subsequent logic levels.

Abstract: A voltage of an input analog signal (105 or 405) can be converted to a signal whose frequency is dependent upon the analog input signal (135 or 435). A frequency divider (115 or 415) can be configured to convert the frequency dependent signal to a frequency divided signal (140 or 440). A first frequency detector (420a) or time detector (120a) can be configured to determine the frequency of the frequency divided signal, thereby creating a first output signal (145a or 445a). A second frequency detector (420b) or time detector (120b) can be configured to determine the frequency of the frequency dependent or non-frequency divided signal, thereby creating a second output signal (145b or 445b). The first and second output signals can be post-processed to generate a digital output signal (130 or 430) that is representative of the input analog signal.

Abstract: A voltage of an input analog signal (105 or 405) can be converted to a signal whose frequency is dependent upon the analog input signal (135 or 435). A frequency divider (115 or 415) can be configured to convert the frequency dependent signal to a frequency divided signal (140 or 440). A first frequency detector (420a) or time detector (120a) can be configured to determine the frequency of the frequency divided signal, thereby creating a first output signal (145a or 445a). A second frequency detector (420b) or time detector (120b) can be configured to determine the frequency of the frequency dependent or non-frequency divided signal, thereby creating a second output signal (145b or 445b). The first and second output signals can be post-processed to generate a digital output signal (130 or 430) that is representative of the input analog signal.

Abstract: A method and circuit for determining variation between an input clock signal (CLK0) and a reference clock signal (REFCLK) is provided. A plurality of time shifted input clock signals (CLK0, CLK1, . . . , CLK09) can be generated from a single input clock signal (CLK0). The plurality of time shifted input clock signals (CLK0, CLK1, . . . , CLK09) can be sampled at successive periodic intervals occurring relative to the reference clock signal (REFCLK). For each of the time shifted input clock signals (CLK0, CLK1, . . . , CLK09), a sampled value for a succeeding and a preceding periodic interval can be compared to determine whether there is a variation between an input clock signal (CLK0) and a reference clock signal (REFCLK).

Abstract: A differential comparator having offset correction and common mode control for providing stable op amp output that changes only due to the original inputs coming into the comparator. The difference comparator has increased common-mode difference tolerance, and large op-amp offset tolerance, as well as fast decision time.

Abstract: Described are high-speed parallel-to-serial converters. The converters include data combiners with differential current-steering circuits that respond to parallel data bits by producing complementary current signals representing a differential, serialized version of the parallel data bits. One embodiment includes complementary data-input transistors to expedite the data combiner's response to changes in input data.

Abstract: A system for calibrating an adjustable termination resistor for a low voltage differential signaling (LVDS) system is provided. The system includes an adjustable termination resistor located on a chip and a reference termination resistor located off the chip. A bias circuit coupled to the adjustable termination resistor and the reference termination resistor causes the same current to flow through the adjustable termination resistor and the reference termination resistor. A comparator is configured to compare a first voltage drop across the adjustable termination resistor and a second voltage drop across the reference termination resistor. A control circuit is coupled to receive an output signal from the comparator. If the output signal indicates that the adjustable termination resistor has a desirable value with respect to the reference termination resistor, then the control circuit stops the calibration operation.

Abstract: A differential comparator having offset correction and common mode control for providing stable op amp output that changes only due to the original inputs coming into the comparator. The difference comparator has increased common-mode difference tolerance, and large op-amp offset tolerance, as well as fast decision time.

Abstract: A communications system includes a communications channel, a first processing unit; and interface unit, and an interrupt controller. The first processing unit is adapted to monitor the communications channel and provide a plurality of status bits. The interface unit includes an interrupt register. The interrupt controller is adapted to identify a plurality of interrupts in response to changes in the status bits. Each interrupt has a priority, and the interrupt controller is adapted to store selected interrupts in the interrupt register in an order determined by the priority of the interrupts. A method includes monitoring a communications channel. A plurality of status bits associated with the monitoring are provided. A plurality of interrupts are identified based on changes in the status bits, each interrupt having a priority. Selected interrupts are stored in an interrupt queue in an order determined by the priority of the interrupts.

Abstract: A differential comparator having offset correction and common mode control providing stable op amp output that changes only due to the original inputs coming into the comparator. The difference comparator has increased common-mode difference tolerance, and large op-amp offset tolerance, as well as fast decision time.

Abstract: Electronic devices are typically coupled together to operate as systems that require the communication of data from one device to another. Many such devices include a ring oscillator, a circuit that generates one or more oscillating signals using a series of interconnected delay circuits. One problem with conventional ring oscillators concerns differences in the signal paths between the delay circuits. Accordingly, the present inventors devised several oscillators having unique layouts, which reduce differences in the signal paths between delay circuits. One exemplary oscillator includes a sequence of delay circuits having input-output connections between at least two pairs of non-adjacent delay circuits. Another exemplary oscillator provides two groups of delay circuits with a bus between the two groups, intercoupling the circuits. And, another exemplary oscillator arranges three or more delay circuits to form a closed loop.

Abstract: A dynamic RAM having two-transistor memory cells includes a top array of memory cells and a bottom array of memory cells, with a sense amplifier disposed between the two halves. The memory cells in each column of the top half are coupled to respective Bit.sub.-- Plus lines, and the memory cells in each column of the bottom half are coupled to respective Bit.sub.-- Minus lines. The Bit.sub.-- Plus lines and the Bit.sub.-- Minus lines are respectively coupled to Plus and Minus inputs of sense amplifiers for each column. One row of the top array includes only dummy cells, and one row of the bottom array includes only dummy cells. When a memory cell in the top array is read, a dummy cell in the lower array is activated, and when a memory cell in the bottom array is read, a dummy cell in the upper array is activated. That way, a two-transistor memory cell array can have a dual-differential bit line feature in order to reduce errors due to noise.

Abstract: A power-cross detection circuit includes a zero crossing detection circuit for detecting a first zero crossing of the current from a first positive half-cycle to a first negative half-cycle, a second zero crossing of the current from a second positive half-cycle to a second negative half-cycle, and a third zero crossing of the current from a third positive half-cycle to a third negative half-cycle and a circuit for detecting a voltage level and outputting a first signal when the voltage level exceeds a predetermined voltage level, between the first zero crossing and the second zero crossing and between the second zero crossing and the third zero crossing. The zero crossing detection circuit outputs a second signal based on the first, second and third zero crossings.

Abstract: A multiplication system performs a series of multiplications and accumulations of plural pairs of first and second operands. The system includes first and second buses, a memory for storing the plural pairs of first and second operands, and a read buffer coupled to the memory for sequentially reading the first and second operands. An accumulator coupled to the first bus receives the first operands from the read buffer and stores the first operands. A multiplier, coupled to the first and second buses, receives the first and second operands in parallel over the first and second buses respectively from the accumulator and the read buffer respectively to provide a series of products. The system further includes an accumulator for accumulating the products to provide a final accumulated product.

Abstract: An apparatus for processing a received signal according to a digital signal processing algorithm having a multiplier and a limit and quantization circuit appropriately connected within the apparatus to permit operation of the multiplier and the limit and quantization circuit in parallel with logic processing by the apparatus. The address bus system of the apparatus is connected to the parallel-connected components and conveys instructions to the parallel-connected components, at least in part, by predetermined address information via the address bus system.

Abstract: The present invention provides an apparatus and method for generating a covariance matrix. According to one aspect of the invention, an apparatus is provided which generally includes a memory, a circular buffer, a multiply-accumulator, and an arithmetic logic unit. The memory contains an array of values representative of a plurality of samples, and the circular buffer is configured to provide a predetermined number of memory locations. A method for generating the covariance matrix is further provided which uses the architecture listed above to efficiently generate a covariance matrix based on the values in the memory. In one aspect of the invention, the method provides that the memory, the circular buffer, the multiply-accumulator, and the arithmetic logic unit, all operate in parallel to fully exploit the resources provided by the architecture.

Abstract: An arithmetic logic unit includes first and second buses for efficient operations upon multiple-bit operands. The arithmetic logic unit includes, in addition to the first and second buses, a shift register having an input coupled to the first bus and an output, a summer having a first input coupled to the shift register output, a second input coupled to the second bus, and an output, and an accumulator having an input coupled to the summer output and an output coupled to the first bus. The arithmetic logic unit further includes a buffer having an input also coupled to the summer output and an output coupled to the second bus. The summer provides two's compliment inversion when required and the shift register performs sign bit force zero, right shifting, and masking operations. In addition, an overflow detector and overflow correction detect and correct overflow conditions without requiring additional operating cycles.