Bandpass Amplifier Research Articles

Broad-Band UHF Distributed Amplifiers Using Band-Pass Filter Techniques

Distributed amplifiers have generally been limited to operation in the vhf region and to application of low pass filter techniques. However, it has been recognized that these limitations do not exist in theory. The basic principles of distributed amplification as applied to the uhf band-pass amplifier are described in this paper. The modifying factors of major importance are evaluated and techniques for optimizing amplifier performance capabilities in the uhf region are discussed. Measured performance characteristics of several amplifiers are presented in order to show the practical capabilities of band-pass amplifiers in the uhf region. In addition performance data for a transistorized distributed amplifier having useful gain to 700 mc are presented.

The Design of Primary and Secondary Radar I.F. Amplifiers

The practical designs of circuitry in primary and secondary radar I.F. amplifiers are considered in detail. They consist of tuned band pass amplifiers with midfrequencies in the range of 30–60 mc./sec. Gains normally required are from 100 to 125 db. and the fractional bandwidths vary from 0·1 to 0·5. In these designs, bandwidth is always measured at 3 db. below peak response.

Etude expérimentale du profil des raies de la série de Paschen de l'atome d'hydrogène, émises en décharge condensée

The shape of the hydrogen lines in emission and absorption is often used for the determination of the electron-density in the plasma. The author has studied the shapes of the Paschen and Balmer lines in the discharge tube with quartz capillary using a 1 μF capacitor (2000 V), which is discharged 50 times per second. The hydrogen pressure in the tube is a few cm of mercury at room temperature. This capillary is imaged on the slit of a grating spectrometer of 2 m focal length and aperture of ƒ/10. A lead-sulphide detector-cell is used and the output signal is amplified by a narrow band-pass amplifier. The results in general confirm the theory of HOLTSMARK about line profiles.

Design of a Simple Band-Pass Amplifier with Approximate Ideal Frequency Characteristics

Design of a Simple Band-Pass Amplifier with Approximate Ideal Frequency Characteristics

A Method of Band-Pass Amplifier Alignment

A method of alignment of band-pass amplifiers is discussed based on the oscilloscopic display of second order harmonic distortion as a function of the carrier frequency departure from the pass-band center. This method of alignment is thought particularly effective for band-pass amplifiers requiring high degree of linearity of transfer phase versus frequency function, such as for example, low-distortion FM intermediate frequency amplifiers.

Design of Optimum Transient Response Amplifiers

This paper describes a method based entirely upon transient considerations for the design of amplifiers with optimum transient response in the "least squared" sense. This method is applicable to video amplifiers, symmetrical band-pass amplifiers, and dissymmetrical band-pass amplifiers used with low-level modulation, and has provisions for taking into account noise acceptance and adjacent channel rejection. Examples are given of the results obtained with this method.

A Recording Spectrometer for Raman Spectroscopy

A description is given of a photoelectric recording spectrometer for Raman spectroscopy incorporating a high-intensity excitation system and a novel amplification device. Operation of the exciting mercury arc lamps from 50 c/s. mains imparts to the light signal, and consequently to the current from the photo-multiplier tube, a 100 c/s. periodicity. After amplification by a narrow band-pass amplifier, rectification is achieved in a push-pull phase-sensitive (homodyne) rectifier, by mixing the signal with a fixed voltage of identical periodicity. The rectified signal is fed through a filter to a cathode follower valve which provides the power to operate a recording milliammeter. This method of rectification, in conjunction with appropriate filter, effectively reduces the bandwidth of the amplifier, with consequent great improvement in the signal/noise ratio. With this arrangement cooling of the photo-multiplier is unnecessary for normal work. Using a spectrometer of small aperture and resolution and a Raman tube of 35 ml. capacity, traces of the Raman spectrum of carbon tetrachloride show no appreciable background noise.

Discussion on "Exact Design and Analysis of Double- and Triple-Tuned Band-Pass Amplifiers" (Milton Dishal)

Discussion on "Exact Design and Analysis of Double- and Triple-Tuned Band-Pass Amplifiers" (Milton Dishal)

Exact Design and Analysis of Double- and Triple-Tuned Band-Pass Amplifiers

The purpose of this paper is to present a quick, complete, and exact method of design and analysis of double- and triple-tuned band-pass amplifiers. The necessary small-percentage pass-band equations are derived giving the relationship between the circuit characteristics and the response characteristics. These circuit characteristics are: the resonant frequency f <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> , coefficient of coupling K, the circuit Q, and the input and output capacitances C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</inf> , and C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">out</inf> . The response characteristics are: the percentage bandwidth between peaks Δf <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> /f <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> , the peak-to-valley response ratio within the pass band V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> I/V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</inf> , the peak-to-"skirt" response ratio V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> /V at different skirt-to-peak bandwidth ratio points Δf/Δf <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> outside the pass band, the circuit gain at the peaks, and the phase shift θ at any frequency. These design equations, extended to the case of one to eight cascaded stages, are incorporated in two sets of conveniently used nomographs, one for double-tuned circuits and one for triple-tuned circuits. Specific examples of the use of these nomographs are given.

The Distribution of Amplitude with Time in Fluctuation Noise

The purpose of this paper is to show that fluctuation noise has a statistical distribution of amplitude versus time which follows the normal-error law. This fact is also correlated with the measurements of crest factor made on the noise output of band-pass amplifiers by various investigators. It is shown that the distribution of noise amplitude continues to follow the normal-error law, even after the noise has been passed through frequency-selective circuits. It is shown why the measurements of crest factor, made by various experimenters, group around the value 4, but it is pointed out that this is not a true crest factor because the voltage occasionally goes considerably higher. The ratio of the average to the effective voltage is shown to be 0.798. A discussion is given of the kinds of noise which do not follow this normal-error law.