High Slew Rate Research Articles

A 400-MHz input flash converter with error correction

An 8-b, 200-megasample/s flash converter with 400-MHz analog bandwidth and error correction circuitry is described. A cascoded input stage and a dense bipolar process make the wide bandwidth possible. Errors arising from high input slew rate and comparator metastability are reduced by means of the circuitry and the latching stages respectively. The final defense against errors is the second rank error suppression. Measured frequency and error rate performance are examined. >

A fully differential sample-and-hold circuit for high-speed applications

A new design technique for realizing a true fully differential sample-and-hold (S/H) circuit is presented. This technique avoids the reset phase and consequently the need for a high slew rate for the operational amplifier, it therefore can be used for high-speed applications. A prototype circuit, which occupies 0.1 mm/sup 2/ in a 3- mu m CMOS process, is integrated and experimental results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Translinear class AB current amplifier

A new translinear class AB current amplifier is presented. Based on current-mode techniques, the circuit is readily configured into a high-performance voltage amplifier yielding wide gain-independent bandwidth and high slew rate, outperforming earlier designs.

Unity power factor high current slew rate magnet power supply

The author presents an alternative design scheme which utilizes a conventional AC-to-DC n-pulse bridge and a DC-side commutation network. With the addition of a commutator, converter device latching current problems are overcome; a current slew rate can be preprogrammed within certain limitations; magnet current can be commutated safely in the event of a line voltage collapse; and the main converter can be designed to operate at rated load with a unity power factor. The major focus of the present work is to develop a simple analytical model of the converter commutator and magnet system suitable for design purposes. The model has been verified experimentally. Practical limitations of this circuit are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A fast offset-free sample-and-hold circuit

A novel circuit technique is presented which uses a CMOS cascode inverter as the buffer to realize an offset-free sample-and-hold stage. This circuit can achieve high-speed operation without requiring high slew rate. Experimental results are given to demonstrate the potential advantages of the scheme.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design of a fast gated charge integrating front end for use in high density CAMAC and fastbus modules

This paper describes the design principles of two versions of a gated charge integrating front end for use with high energy physics particle detectors. The current integration, gate and clear problems are discussed. A high slew rate design and its implementation on a very small printed circuit board is presented. The design of a 32 channel, 12 bit CAMAC charge integrating ADC is outlined.

Optimal pacemaker sensing with respect to amplitude and slew rate of intracardiac electrograms: theoretical analysis by computer simulation.

The optimal amplitude and slew rate of intracardiac electrograms for pacemaker sensing were examined on a theoretical basis by computer simulation. The simulation was based on the concept that it is the voltage at the position of the pacing electrode in an electrical field of a moving electrical dipole. By changing the distance between the electrode and the myocardium and the moving velocity of the electrical dipole, simulated ECGs with arbitrary amplitudes and slew rates were generated by the computer and fed to a bandpass filter. This filter was equivalent to those assembled in some models of permanent pacemakers and had a center pass-band frequency of 50 Hz and a Q of 1.0. The outputs of the filter were measured. The results showed that, for pacemakers sensing, simulated intracardiac electrograms with high amplitude should have high slew rates and those with low amplitudes should have low slew rates, although the absolute values depend on the characteristics of the bandpass filter and the sensing threshold of the pacemaker.

Integrated dc SQUID magnetometer with a high slew rate

We have fabricated a magnetometer in which the thin-film superconducting pick-up loop and dc SQUID are integrated on a single silicon chip. The magnetometer, which is intended primarily for geophysical applications, has a magnetic field sensitivity of typically 5×10−15 T Hz−1/2 at frequencies above about 10 Hz, and 2×10−14/( f /1 Hz)1/2 T Hz−1/2 at lower frequencies. The dynamic range is ±2×107 Hz1/2 and the maximum slew rate is about 4×10−3 T s−1 at 6 kHz. This high slew rate enables the magnetometer to be operated in a flux-locked loop for long periods of time without losing lock.

Switched-capacitor FSK modulator and demodulator in CMOS technology

A switched-capacitor FSK modulator/demodulator built in silicon-gate CMOS technology is described. The modulator is based on a programmable harmonic oscillator using two stray-insensitive integrators. The centerpiece of the FSK demodulator is a switched-capacitor voltage-controlled oscillator. A simple post-detection processor restores the digital data. Both circuits have been designed for the 600-baud modem channel with 1500 Hz center frequency and /spl plusmn/200 Hz frequency shifts, but the demodulator operates in the 1200-baud channel as well. Due to dynamic biasing the operational amplifiers feature high slew rate, high voltage gain, and low power for capacitive loads.

Integrated dc SQUID (superconducting quantum interference device) magnetometer with a high slew rate : Wellstood, Frederick, C. Heiden and John Clarke, 1984. Rev. scient. Instrums, 55(6):952–957. Dept. of Phys., Univ. of Calif., Berkeley, Calif. 94720, USA

Integrated dc SQUID (superconducting quantum interference device) magnetometer with a high slew rate : Wellstood, Frederick, C. Heiden and John Clarke, 1984. Rev. scient. Instrums, 55(6):952–957. Dept. of Phys., Univ. of Calif., Berkeley, Calif. 94720, USA

Nonlinear Ramp Generators

Several circuits generating nonlinear time functions by digital techniques are shown. The functions we treat are logarithmic, exponential, square root law, and quadratic law. The specific advantages, general characteristics, and criteria for the selection of components are discussed. Simplicity and high slew rate capability are the main advantages of these circuits.

High slew rate CMOS operational amplifier employing internal transistor compensation

A compact, high slew rate, low distortion CMOS operational amplifier employing an internal feedback transistor instead of the more usual compensation capacitor is reported, which is fabricated using an n-well CMOS silicon-gate technology. The operational amplifier has an open-loop gain exceeding 60dB, a slew rate of +36/−50 V per microsecond, a one-per-cent settling time of 0.25 microsecond, a total harmonic distortion of −73 dB and a power dissipation of 11.5 mW. The design principles are summarised with particular emphasis on the novel transistor feedback compensation circuit. Results for a switched-capacitor filter employing such an operational amplifier are summarised.

Diabatic field ionisation of highly excited indium atoms

The phenomenon of diabatic ionisation of indium Rydberg atoms by an external electric field has been investigated. The indium atoms are excited in an atomic beam apparatus to high lying p states by stepwise laser excitation. The authors have studied the dependence of the ionisation processes on the slew rate of the applied electric field. The observation of a new diabatic ionisation feature for high slew rates is reported and an explanation is presented. Consequences for the ionisation efficiency are mentioned.

The use of current amplifiers for high performance voltage applications

A current amplifier is used to realize a voltage amplifier having an improved high frequency response and slew rate capability. It is shown that the closed loop bandwidth is independent of the closed loop voltage gain. The design and application of a unity gain and a high gain current amplifier to voltage signal processing circuits are given. The results demonstrate an efficient use of the inherent frequency response capabilities of the active devices in the circuit to achieve the amplification of high frequency and large amplitude voltage signals.

Low drift high sensitivity magnetization measurements using a fast squid system

Combining a SQUID of high slew rate, a variable flux transformer, and a temperature controlled sample holder leads to a versatile system for magnetization measurements with high sensitivity and very low drift. The performance of the system is illustrated by magnetization curves from a thin Fe-whisker with large Barkhausen jumps.

An input stage transconductance reduction technique for high-slew rate operational amplifiers

The use of input stage transconductance reduction as a means of decreasing monolithic op amp die size and increasing slew rate is discussed. A new input stage circuit which provides improved slew rate is presented and compared to earlier techniques.

High slew rate monolithic operational amplifier using compatible complementary P-N-P's

An internally compensated monolithic operational amplifier, fabricated using only junction-isolated bipolar processing, slews in excess of 500 V//spl mu/s, and settles to within 0.1 percent in 200 ns as a pulse inverter. Performance in the noninverting mode is only slightly degraded in comparison with the inverting mode. In addition, the following performance levels have been achieved: 50-MHz unity-gain bandwidth with 96-dB open-loop gain, 30-mW quiescent power at /spl plusmn/3 V, /spl plusmn/50-mA output current capability, and output voltage to within 0.5 V of either supply. In order to achieve the above performance, the following innovations were made: 1) a process for junction-isolated compatible complementary p-n-p transistors with low collector series resistance, 2) a high-speed class-B output stage, 3) push-pull middle stages, 4) driven internal reference voltages locked to the noninverting input, and 5) very small voltage drops across large internal shaping capacitors which permit use of high-capacitance junctions.

MOS-bipolar monolithic integrated circuit technology

A technique for the fabrication of p-channel MOS transistors and bipolar transistors within monolithic integrated circuits is described. Total process compatibility has been achieved without compromising either the n-p-n bipolar or p-channel MOS characteristics. The technology developed is similar to that used for conventional integrated circuits until the channel oxidation step, A low temperature oxidation followed by a high temperature anneal process that produces negligible changes in preceding diffusion profiles was used to form this oxide. Bias temperature tests of MOS capacitors have shown the oxide to be reproducibly free of contamination. A high slew rate MOS bipolar operational amplifier has been designed and fabricated on 0.045- by 0.045-in chip using the new technology. Typical characteristics are slew rate =80 V/µs voltage gain = 70 dB. The MOS transistors are used as active loads and level shifters in this circuit and provide a much improved frequency response over conventional circuits using p-n-p lateral transistors.

Critical Gas Bearing Slew Test Evaluation With a Varmeter

In the Pendulous Integrating Gyro Accelerometer (PIGA) used in inertial guidance systems, the gas bearing wheel is operated in a slewing mode at high slew rates. The high performance criteria of the guidance system require that the gas bearing operate without degradation and without loss of synchronous spin velocity at high slew rates. Size and weight restrictions limit the available support area, requiring that the gas bearing be operated near its maximum capability under high slew rates. An MIT-designed varmeter has been a proven tool to critically evaluate gas bearing performance under high slew rates. The varmeter is sensitive to slightest contact between the rotating member and a stationary member and can detect the slightest loss of synchronous speed.