Abstract: A decimation filter has a low pass first stage of filtering in which multiple taps from a plurality of delay stages are summed together and then integrated to thereby provide suppression of high frequency noise in the input signal.

Abstract: The column surrounding an electron or ion beam is shielded with a second shield which is outside the column and isolated from the column, being connected to chassis ground at a location remote from the column. Also, wiring into the column is double shielded with the shields connected to ground at the end remote from the column and not at the column itself.

Abstract: A digital parallel multiplier having encoders for each segmented bit pair of the multiplier input data and which selects one of 4 coefficients, based on the sum of the bit pair, that are then applied to the multiplicand input data to form a plurality of factored multiplicands. The sum of the factored multiplicands is augmented by two additional bits for all but the last of the factored multiplicands and by a logic 1 bit. The two additional bits are a logic 1 followed by the inverse of the sign bit of the factored multiplicand and are placed in the next two significant bit positions after the sign bit of the factored multiplicand, and the logic 1 is in the position occupied by the sign bit of the factored multiplicands which has the least significant bit position of all of the sign bits of the factored multiplicands.

Abstract: A digital parallel multiplier having encoders for each segmented bit pair of the multiplier input data and which selects one of 4 coefficients, based on the sum of the bit pair, that are then applied to the multiplicand input data. When a 3X coefficient of the multiplicand input data is to be generated, a -1 coefficient is output by the encoder requiring the 3X coefficient, and a 1 is added to the sum of the next most significant bit pair.

Abstract: A multiplier using a modified Booth algorithm dissipates power proportional to the magnitude of one of the operands, and logic races are eliminated using iterative networks.

Abstract: A synchronous serial communication link between a controller and a peripheral is resynchronized by the sending of a series of bits at a first logic level by the controller. The series of bits is long enough to ensure that the peripheral will decode a command word in which all of the bits are at the first logic level. The peripheral, upon decoding such a command word, resets the synchronization circuitry within the peripheral. The controller then sends a single bit of the opposite logic state followed by serial data. The peripheral, upon receipt of this bit of the opposite logic state, releases the synchronization circuitry from its reset condition and begins to decode the serial data in synchronization with the controller.

Abstract: A 1-bit discrete time digital-to-analog converter which samples a reference voltage and ground potential onto two charging capacitors during a sample phase of each sampling period, and which transfers the charge on one of the capacitors, as determined by a digital input signal, onto an integrator during a transfer phase of said sampling circuit, draws current from the reference voltages which is independent of the data into the converter. The improvement comprises the addition of at least one phase to each sampling period so that the current drawn from said reference voltage is essentially independent of said digital input signal.

Abstract: The detrimental nonlinear charging currents from an analog input signal through an anti-aliasing filter into a sampling circuit can be minimized by using primary and secondary inputs to the sampling circuit. The secondary input is turned on before the primary input and the charge required to charge the parasitic capacitance inside the sampling circuit and to replenish the channeling charge lost in the previous cycle is supplied primarily through the secondary input. Immediately after the secondary input is turned off the primary input is connected to the sampling node, and only the charge required to fine tune the signal into the sampling capacitor is drawn through the primary input. Therefore, most of the non-linear charge injection is passed through the secondary input, and the signal passed through the primary input is used to fine tune the voltage levels inside the sampling circuit during the actual sampling operation.

Abstract: A non-volatile memo includes the reference cells programmed to opposite logic states whose outputs are combined and then equally divided to provide a reference signal to a sense amplifier which is one half of the sum of the signals from a high conductivity data cell and a low conductivity data cell. The non-volatile memory also includes a bias voltage generator which uses a high conductivity non-volatile reference cell for a reference, and which produces a bias voltage which is coupled to current limiting transistors at the inputs of the sense amplifier so that the current into the sense amplifier is limited and therefore limits the power used by the non-volatile memory.

Abstract: A stereo digital-to-analog converter is able to operate in an 8 pin package yet to operate under a variety of serial data input formats. The normal de-emphasis pin can be used for receiving a static de-emphasis signal, an external serial clock, or programming data for the serial data formats. In addition metal and wire bond options are used to provide more flexibility in the manufacturing process.

Abstract: A decimation filter includes a plurality of integration stages, at least one decimation stage, and a plurality of differentiation stages followed by a FIR filter. At least one of the integration stages, the decimation stage, and the differentiator stages, and the FIR filter are implemented in a single ALU which includes a single adder, a ROM, and a RAM. The different sampling rates of the integrator stage and the FIR filter requires the storage of intermediate results in RAM of the FIR filter calculations.

Abstract: A ratiometric converter receives an external sense signal and external reference signal and provides an output signal which is proportional to the sense signal and inversely proportional to the reference signal. Electromagnetic interference and noise coupled onto the sense and reference lines are effectively removed by converting the sense signal to a digital signal and converting the reference signal to a digital signal. The digital sense signal is then filtered through a low pass filter to provide a filtered signal, and similarly, the digital reference signal is filtered through a low pass filter to provide a filtered digital reference signal. A divider circuit then divides the filter digital sense signal by the filter digital reference signal to provide the output signal.

Abstract: A 1-bit discrete time digital-to-analog converter which samples a reference voltage and ground potential onto two charging capacitors during a sample phase of each sampling period, and which transfers the charge on one of the capacitors, as determined by a digital input signal, onto an integrator during a transfer phase of said sampling circuit, draws current from the reference voltages which is independent of the data into the converter. The improvement comprises the addition of at least one phase to each sampling period so that the current drawn from said reference voltage is essentially independent of said digital input signal.

Abstract: The output gates of a delta-sigma modulator can generate i(t) transient signal in the power supply lines of a delta-sigma modulator. These i(t) spikes, which would otherwise produce non-linearities which can be coupled into the frequency band of interest of the modulator, are made to be linear by using return-to-zero data encoding and by providing multi-bit outputs to the delta-sigma modulator in which the output states all have equal numbers of logic ones at the output lines for each of the output states.

Abstract: A switched-capacitor integrator with chopper stabilization performed at the sampling rate virtually eliminates the flicker noise and any low frequency interference generated by the amplifier. The integrator samples the input and then passes the sampled input to the feedback capacitor during each chopping phase of the amplifier to thereby provide a double-sampled integrator. The output of the integrator is sampled at the end of each cycle of the chopping signal.

Abstract: An audio mixer circuit on an integrated circuit chip performs a calibration operation on power up which calibrates out most of the offset voltages of the operational amplifiers used in the mixer. The calibration logic includes a shared calibrate circuit which provides timing signals to each operational amplifier and its associated calibration circuitry. The calibration operation is performed by digitally controlling and changing the bias current into each of the operational amplifiers until the offset voltage is compensated. A class A flip-flop circuit is used in the digital counter of the calibration circuitry to drive a current digital-to-analog converter.

Abstract: The thermal noise generated through the feedback capacitor of a delta-sigma modulator is attenuated by transferring a reference voltage through the capacitor in two separate steps during each sampling period. This permits a reduction in the size of the feedback capacitor, thereby reducing thermal noise, without increasing the voltage on the switching capacitors on the summing node side of the feedback capacitors which would induce degradation due to hot electron effects.

Abstract: A low drift integrated circuit resistor structure has a forced high end and a forced low end. A sense high connection is located proximate to the force high connection, and a sense low connection is located proximate to the force low connection. The structure also has at least one internal sense connection. This structure can be used in an instrumentation amplifier that includes an operational amplifier which regulates the current between the force high connection and the force low connection in response, in part, to the current sensed in the internal sensing connection of the resistor structure. The sense high connection and the sense low connection form the outputs of the instrumentation amplifier.

Abstract: A fuse protection circuit for an electrically programmable read only memory circuit consists of a fusing element such as an antifuse connected between a bitline and the drain of the access transistor, and which is susceptible to inadvertent activation due to programming voltages applied to the bitline when the access transistor is not being addressed. The fusing element is protected from such inadvertent activation by the addition of a capacitor between the drain of the access transistor and the bitline.

Abstract: A low drift integrated circuit resistor structure has a forced high end and a forced low end. A sense high connection is located proximate to the force high connection, and a sense low connection is located proximate to the force low connection. The structure also has at least one internal sense connection. This structure can be used in an instrumentation amplifier that includes an operational amplifier which regulates the current between the force high connection and the force low connection in response, in part, to the current sensed in the internal sensing connection of the resistor structure. The sense high connection and the sense low connection form the outputs of the instrumentation amplifier.