Amplifiers – Signal feedback – Variable impedance in feedback path varied by separate...
Patent
1982-03-18
1984-09-25
Mullins, James B.
Amplifiers
Signal feedback
Variable impedance in feedback path varied by separate...
330278, H03F 134, H03G 318
Patent
active
044738021
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to devices for converting electrical signals, and more particularly to electrical signal converters with step variable gain.
DESCRIPTION OF THE PRIOR ART
Conversion of electrical signals in a step variable manner is carried out by varying, in accordance with a predetermined step function of time, the gain of a circuit, the input of which is supplied with the signal to be converted.
Known in the art is an electrical signal converter with step variable gain comprising a variable gain circuit, the output of which is the output of the converter, and a sequencer having its outputs connected to the control inputs of the variable gain circuit for varying the gain of the variable gain circuit according to a step function of time (cf. "Analog Integrated Circuits - Devices, Circuits, Systems and Applications", Contributed Editor J. A. Connelly A Wiley-Interscience Publication, John Wiley and Sons, New York, London, Sydney, Toronto, 1975).
Variation of the gain of such a converter depends completely on variation of the gain of the variable gain circuit so that deviations of the latter gain from the assigned values lead to the same deviations in the gain of the converter. At the same time, the gain of the variable gain circuit is affected by changes in the resistance of the converter load, the influence of the load being the greater, the smaller is the load resistance. Therefore, variations in the load resistance bring about deviations of the converter gain from the assigned law of its variation thus reducing the accuracy of the conversion of the input signal. If the load resistance is largely determined by reactive elements, which, for example, is the case when a coaxial cable having a considerable capacitance is connected to the output of the converter, the influence of the load resistance on the converter gain causes an increase in the transient response time when the gain is abruptly changed in accordance with the predetermined step function. This also leads to a poorer conversion accuracy.
It is possible to diminish the influence of the load resistance by reducing the output resistance of the variable gain circuit, i.e., by using a more powerful amplifier in said circuit. Such an amplifier, however, has a lower response speed, which means a greater transient response time and, hence, greater distortions in the output signal waveform.
SUMMARY OF THE INVENTION
The principal object of the present invention is to provide an electrical signal converter with step variable gain which is designed so as to diminish the influence of the magnitude and of the reactive properties of the converter load on the converter gain and thus to ensure a more accurate conversion of the input signal.
With this principal object in view, there is proposed an electrical signal converter with a step variable gain comprising a variable gain circuit, the output of which is the output of the converter, and a sequencer having its outputs connected to the control inputs of the variable gain circuit for varying the gain of the variable gain circuit according to a step function of time. According to the invention, the converter further comprises a second variable gain circuit and a comparison circuit connected so that they form a negative feedback path between the output and the input of the variable gain circuit whose output is the output of the converter, the input of the second variable gain circuit being connected to the output of the variable gain circuit whose output is the output of the converter. The control inputs of the second variable gain circuit are connected to the outputs of the sequencer for varying the gain of the second variable gain circuit in inverse proportion to the step function according to which the gain of the variable gain circuit, whose output is the output of the converter, is varied. One input of the comparison circuit is the input of the converter, another input of the comparison circuit is connected to the output of the second variable gain circuit; and the
REFERENCES:
patent: 3482084 (1969-12-01), Trusov et al.
Min Mart V.
Parve Toomas E.
Pungas Toom A.
Mullins James B.
Wan G.
LandOfFree
Electrical signal converter with step variable gain does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrical signal converter with step variable gain, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical signal converter with step variable gain will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1771414