Abstract: Pipeline analog-to-digital converters (ADCs) are commonly used for high frequency applications; however, operating at high sampling rates will often result in high power consumption or tight timing constraints. Here, though, an ADC is provided that allows for relaxed timing (which enables a high sampling rate) with low power consumption. This is accomplished through the use of multiplexed, front-end track-and-hold (T/H) circuits that sample on non-overlapping portions of a clocking signal in conjunction with “re-used” or shared analog processing circuitry.

Abstract: Pipeline analog-to-digital converters (ADCs) are commonly used for high frequency applications; however, operating at high sampling rates will often result in high power consumption or tight timing constraints. Here, though, an ADC is provided that allows for relaxed timing (which enables a high sampling rate) with low power consumption. This is accomplished through the use of multiplexed, front-end track-and-hold (T/H) circuits that sample on non-overlapping portions of a clocking signal in conjunction with “re-used” or shared analog processing circuitry.

Abstract: System and method for improved time-interleaved analog-to-digital converter arrays which reduces sampling mismatch distortion found in prior art arrays. There may be two causes of non-uniform sampling mismatch in a TI-ADC array, a mismatch due to skew and a mismatch due to clock jitter. To minimize non-uniform sampling mismatch, the mismatch due to skew can be addressed. A preferred embodiment comprises adjusting a delay imparted on the sampling clock by an adjustable delay in each channel of a plurality of channels in the TI-ADC array to minimize skew and randomly switching between two delays that span a zero-skew delay to reduce residual skew in each channel and thus eliminate (or reduce) frequency domain tones caused by non-uniform sampling mismatch.

Abstract: An analog-to-digital converter apparatus has a plurality of stages. Each stage includes a residue amplifier having a first and second amplifier unit. Each of the amplifier units has a first input locus, a second input locus and an output locus. The amplifier units cooperate in receiving a differential input data signal at the first input loci. A DC level setting signal unit is coupled with the second input loci and provides a DC level setting current in a first current direction. A counter-current signal generating unit is coupled with the second input loci via a single coupling locus common with the second input loci and provides a control current signal to the second input loci in a second current direction opposite to the first current direction. The control current signal provides a DC level control for each of the amplifier units.

Abstract: A circuit and method that provides a cascode current source/sink with high output impedance. In one example, the dependency on the external load is reduced by directing a compensation current corresponding to change in base current in the cascode (Q1) in an approach such that the compensation current cancels out the error of the cascode (Q1). In a further example, biasing circuitry (200) is included and arranged such that change in base current of the cascode (Q1) is detected and a corresponding current is summed at the emitter of the cascode (Q1) such that the collector current of the cascode (Q1) remains unchanged.

Abstract: A circuit and method that provides a cascode current source/sink with high output impedance. In one example, the dependency on the external load is reduced by directing a compensation current corresponding to change in base current in the cascode (Q1) in an approach such that the compensation current cancels out the error of the cascode (Q1). In a further example, biasing circuitry (200) is included and arranged such that change in base current of the cascode (Q1) is detected and a corresponding current is summed at the emitter of the cascode (Q1) such that the collector current of the cascode (Q1) remains unchanged.

Abstract: Echo cancellation in data communication between modems utilizes analog echo cancellation to lessen reduction of usable dynamic range of the received signal at the input to the analog-to-digital converter (DAC) in the receiver. Two digital-to analog (D/A) conversions are provided in the modem's analog front end (AFE). One generates the analog signal for transmission. The other generates an analog representation of a cancellation signal that is used to electronically cancel the echo before analog-to-digital (A/D) conversion of the received signal. A preferred embodiment utilizes multiplexed DAC architecture to emulate two DACs by sharing DAC circuitry between data paths of the two D/A conversions.

Abstract: A buffer circuit includes a differential pair output switch having an additional NPN device and resistor operational to increase the common mode output voltage of the buffer during a switching event, such that the voltage movement at the common emitter node of the differential pair output switch for the buffer circuit is decreased to substantially reduce distortion of an output signal associated with a DAC that employs the buffer circuit.

Abstract: A current correction circuit 500 eliminates beta mismatches between a thermometer encoded segment 102 and a R-2R ladder segment 106 of a current steering digital-to-analog converter 100. The circuit 500 consists of three replica MSB unit current sources, I1, I2 and I3. The replica current I1 acts as a replica to a cascode device 206 of the MSB unit 200 of the current steering DAC 100. The replica current I2 replicates an effective base current equal to the total base current in the R-2R ladder circuit portion 300 of the current steering DAC 100. The replica current I3 replicates the total base current of the L output switches 310 in the LSB segment 106 of the current steering DAC 100. A high impedance summing node 506 produces a correction current ICOR=I1−(I2+I3). This current is equal to the current difference between an MSB unit 200 and the LSB segment 106.

Abstract: A buffer circuit includes a differential pair output switch having an additional NPN device and resistor operational to increase the common mode output voltage of the buffer during a switching event, such that the voltage movement at the common emitter node of the differential pair output switch for the buffer circuit is decreased to substantially reduce distortion of an output signal associated with a DAC that employs the buffer circuit.

Abstract: A current correction circuit 500 eliminates beta mismatches between a thermometer encoded segment 102 and a R-2R ladder segment 106 of a current steering digital-to-analog converter 100. The circuit 500 consists of three replica MSB unit current sources, I1, I2 and I3. The replica current I1 acts as a replica to a cascode device 206 of the MSB unit 200 of the current steering DAC 100. The replica current I2 replicates an effective base current equal to the total base current in the R-2R ladder circuit portion 300 of the current steering DAC 100. The replica current I3 replicates the total base current of the L output switches 310 in the LSB segment 106 of the current steering DAC 100. A high impedance summing node 506 produces a correction current ICOR=I1−(I2+I3). This current is equal to the current difference between an MSB unit 200 and the LSB segment 106.

Abstract: A pipeline analog-to-digital conversion system (10) includes a plurality of cascaded subconverter stages (12) and a digital correction unit (16). Each subconverter stage (12) includes an n-bit analog-to-digital converter (26), an n-bit digital-to-analog converter (28), and an arithmetic unit (32). The n-bit analog-to-digital converter (26) generates a second intermediate digital signal (18) as a function of a first input analog signal (24) and a corresponding first intermediate digital signal (18) received from a previous stage (12).

Abstract: A pipeline analog-to-digital conversion system (10) includes a plurality of cascaded subconverter stages (12) and a digital correction unit (18). Each subconverter stage (12) includes an n-bit analog-to-digital converter (36), an n-bit digital-to-analog converter (38), and an arithmetic unit (42). Arithmetic unit (42) simultaneously samples a second input analog signal (34) and produces an output analog signal (44) representative of the difference between a first input analog signal (32) and a corresponding intermediate analog signal (40).

Abstract: A new artificial boulder for easy placement and easy portability. The inventive device includes a shell having a top portion, a bottom portion, an exterior surface, an inner surface. The exterior surface of the shell is designed formed to resemble the exterior surface of a boulder. The inner surface of the shell defines a cavity. A plurality of spaced apart anchor tabs are coupled to the bottom portion of the shell. Each anchor tab has a hole for extending a stake therethrough to secure the shell to a ground surface.

Abstract: Methods and apparatus for an analog-to-digital converter (ADC) with reduced comparator-hysteresis effects. One embodiment uses a charge-redistribution ADC. One method performs an initial coarse analog-to-digital conversion to avoid overdriving an analog voltage comparator. One such method includes a redundant capacitor in an array of charge-redistribution capacitors used in the ADC for sample-and-hold and successive-approximation functions. Another method performs a traditional initial successive-approximation analog-to-digital conversion, and then performs an additional conversion-step test based on the least-significant bit of the initial result to correct for comparator errors in the initial conversion.