Abstract An amplifier circuit for the unadulterated transmission of phase information of a supplied ac voltage signal over a large dynamic range includes a series connection of a series of similar amplifier stages each of which is followed by a symmetrical limiter. The amplifier operates as a logarithmic amplifier for maintaining the amplitude information of the supplied ac signal. Each of the amplifier stages comprise an emitter-base transistor amplifier circuit having negative feedback and an output circuit which contains a resonant circuit which is strongly damped by an attenuating resistor and whose capacitance is formed by a trimmer capacitor connected in parallel to a pair of diodes. The diodes are connected in anti-parallel relation to one another and represent the limiter. The capacitance is adjustable for purpose of impedance adjustment and is set in such a manner that the resultant resonant circuit impedance is capacitive.
A multi-stage limiter amplifier for amplifying an ac voltage of a specific frequency which may have been subjected to large level fluctuations, comprising: a plurality of serially-connected amplifier stages each including a feedback amplifier and a pair of limiter diodes connected to the output of said feedback amplifier, said diodes connected in opposite polarity and in parallel and having a symmetrical limiting effect, each of said amplifier stages including a transistor amplifier circuit comprising an output circuit including a parallel resonant circuit, a damping impedance strongly damping said parallel resonant circuit, said parallel resonant circuit including a trimmer capacitor connected in parallel to said limiter diodes for rendering said impedance capacitive.
Claim 2
Dependent Claim
111 words
A multi-stage limiter amplifier for amplifying an ac voltage of a specific frequency which may have been subjected to large level fluctuations, comprising: a plurality of serially-connected amplifier stages each including a feedback amplifier and a pair of limiter diodes connected to the output of said feedback amplifier, said diodes connected in opposite polarity and in parallel and having a symmetrical limiting effect, each of said amplifier stages including a transistor amplifier circuit comprising an output circuit including a parallel resonant circuit, a damping impedance strongly damping said parallel resonant circuit, said parallel resonant circuit including a trimmer capacitor connected in parallel to said limiter diodes for rendering said impedance capacitive.
Claim 3
Dependent Claim
49 words
The amplifier of claim 1, comprising: a plurality of rectifiers connected to the limiter diodes at the outputs of said amplifier stages; and adding means connected to said rectifiers for providing an output signal which is at least approximately the logarithmic of the signals received by said amplifier stages.
Claim 4
Dependent Claim
25 words
The amplifier of claim 2, comprising: a plurality of buffer amplifiers, each of said buffer amplifiers connected between said amplifier stages and said adding means.
Claim 5
Dependent Claim
39 words
The amplifier of claim 2, wherein: the amplification of each of said amplifier stages is small compared to the total required amplification thereby requiring a larger number of said amplifier stages for more accurate conformity to a logarithmic characteristic.