|  | H |
SECTION H — ELECTRICITY

|  | H03 |
BASIC ELECTRONIC CIRCUITRY

|  | H03F |
AMPLIFIERS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; masers, lasers Fulltext... Hierarchy... Expanded...H01S; coupling arrangements quite independent of the nature of the amplifier Fulltext... Hierarchy... Expanded...H03H; amplifiers capable only of dealing with pulses Fulltext... Hierarchy... Expanded...H03K)

|  | H03F |
Note(s) This sub-class deals with (a) linear amplification, there being linear relationship between the amplitudes of input and output, and the output having substantially the same waveform as the input, (b) dielectric amplifiers, magnetic amplifiers, and parametric amplifiers when used as oscillators or frequency-changers, and (c) constructions of active elements of dielectric amplifiers and parametric amplifiers for which no provision exists elsewhere.

|  | H03F 1/00 |
Details of amplifiers with only discharge tubes, or only semiconductor devices as amplifying elements

|  | H03F 1/02 |
· | Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation

|  | H03F 1/04 |
· · | in discharge-tube amplifiers

|  | H03F 1/06 |
· · · | to raise the efficiency of amplifying modulated radio frequency waves, e.g. Doherty type; to raise the efficiency of amplifiers acting also as modulators

|  | H03F 1/08 |
· | Modifications of amplifiers to reduce influences of internal impedances of amplifying elements (wide-band amplifiers with inter-stage coupling networks incorporating these impedances Fulltext... Hierarchy... Expanded...H03F 1/42)

|  | H03F 1/10 |
· · | by use of amplifying elements with multiple electrode connections

|  | H03F 1/12 |
· · | by use of attenuating means

|  | H03F 1/14 |
· · | by use of neutralising means

|  | H03F 1/16 |
· · · | in discharge-tube amplifiers

|  | H03F 1/18 |
· · | by use of distributed coupling

|  | H03F 1/20 |
· · · | in discharge-tube amplifiers

|  | H03F 1/22 |
· · | by use of cascode coupling, i.e. earthed cathode or emitter stage followed by earthed grid or base stage respectively

|  | H03F 1/24 |
· · · | in discharge-tube amplifiers

|  | H03F 1/26 |
· | Modifications of amplifiers to reduce influence of noise generated by amplifying elements

|  | H03F 1/28 |
· · | in discharge-tube amplifiers

|  | H03F 1/30 |
· | Modifications of amplifiers to reduce influence of variations of temperature or supply voltage (by negative feedback Fulltext... Hierarchy... Expanded...H03F 1/34)

|  | H03F 1/32 |
· | Modifications of amplifiers to reduce non-linear distortion (by negative feedback Fulltext... Hierarchy... Expanded...H03F 1/34)

|  | H03F 1/34 |
· | Negative-feedback-circuit arrangements with or without positive feedback (Fulltext... Hierarchy... Expanded...H03F 3/50 takes precedence; for neutralisation purposes Fulltext... Hierarchy... Expanded...H03F 1/14)

|  | H03F 1/36 |
· · | in discharge-tube amplifiers

|  | H03F 1/38 |
· | Positive-feedback circuit arrangements without negative feedback

|  | H03F 1/40 |
· · | in discharge-tube amplifiers

|  | H03F 1/42 |
· | Modifications of amplifiers to extend the bandwidth

|  | H03F 1/44 |
· · | of tuned amplifiers

|  | H03F 1/46 |
· · · | with tubes only

|  | H03F 1/48 |
· · | of aperiodic amplifiers

|  | H03F 1/50 |
· · · | with tubes only

|  | H03F 3/00 |
Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements

|  | H03F 3/02 |
· | with tubes only (subsequent sub-groups take precedence)

|  | H03F 3/04 |
· | with semiconductor devices only (subsequent sub-groups take precedence)

|  | H03F 3/06 |
· · | using hole storage effect

|  | H03F 3/08 |
· · | controlled by light

|  | H03F 3/10 |
· · | with diodes

|  | H03F 3/12 |
· · · | with Esaki diodes

|  | H03F 3/14 |
· · | with amplifying devices having more than three electrodes or more than two PN junctions

|  | H03F 3/16 |
· · | with field-effect devices

|  | H03F 3/18 |
· | with semiconductor devices of complementary types (subsequent sub-groups take precedence)

|  | H03F 3/20 |
· | Power amplifiers, e.g. Class B amplifier, Class C amplifier (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03F 3/26-H03F 3/32 take precedence)

|  | H03F 3/22 |
· · | with tubes only (Fulltext... Hierarchy... Expanded...H03F 3/24 takes precedence)

|  | H03F 3/24 |
· · | of transmitter output stages

|  | H03F 3/26 |
· | Push-pull amplifiers; Phase-splitters therefor (duplicated single-ended push-pull arrangements or phase-splitters therefor Fulltext... Hierarchy... Expanded...H03F 3/30)

|  | H03F 3/28 |
· · | with tubes only

|  | H03F 3/30 |
· | Single-ended push-pull amplifiers; Phase-splitters therefor

|  | H03F 3/32 |
· · | with tubes only

|  | H03F 3/34 |
· | Dc amplifiers in which all stages are dc-coupled

|  | H03F 3/36 |
· · | with tubes only

|  | H03F 3/38 |
· | Dc amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers (modulators in general Fulltext... Hierarchy... Expanded...H03C; demodulators in general Fulltext... Hierarchy... Expanded...H03D)

|  | H03F 3/40 |
· · | with tubes only

|  | H03F 3/42 |
· | Amplifiers with two or more amplifying elements having their dc paths in series, the control electrode of each element being excited by at least part of the input signal, e.g. so-called totem-pole amplifiers

|  | H03F 3/44 |
· · | with tubes only

|  | H03F 3/46 |
· | Reflex amplifiers

|  | H03F 3/48 |
· · | with tubes only

|  | H03F 3/50 |
· | Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower

|  | H03F 3/52 |
· · | with tubes only

|  | H03F 3/54 |
· | Amplifiers using transit-time effect in tubes

|  | H03F 3/56 |
· · | using klystrons

|  | H03F 3/58 |
· · | using travelling-wave tubes

|  | H03F 3/60 |
· | Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators (Fulltext... Hierarchy... Expanded...H03F 3/54 takes precedence)

|  | H03F 3/62 |
· | Two-way amplifiers

|  | H03F 3/64 |
· · | with tubes only

|  | H03F 3/66 |
· | Amplifiers simultaneously generating oscillations of one frequency and amplifying signals of another frequency

|  | H03F 3/68 |
· | Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics

|  | H03F 5/00 |
Amplifiers with both discharge tubes and semiconductor devices as amplifying elements

|  | H03F 7/00 |
Parametric amplifiers

|  | H03F 7/02 |
· | using variable-inductance element; using variable-permeability element

|  | H03F 7/04 |
· | using variable-capacitance element; using variable-permittivity element

|  | H03F 7/06 |
· | with electron beam tube

|  | H03F 9/00 |
Magnetic amplifiers

|  | H03F 11/00 |
Dielectric amplifiers

|  | H03F 13/00 |
Amplifiers using amplifying element consisting of two mechanically- or acoustically-coupled transducers, e.g. telephone-microphone amplifier

|  | H03F 15/00 |
Amplifiers using galvano-magnetic effects not involving mechanical movement, e.g. using Hall effect

|  | H03F 17/00 |
Amplifiers using electroluminescent element or photocell

|  | H03F 19/00 |
Amplifiers using superconductivity effects

|  | H03F 21/00 |
Amplifiers not covered by groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03F 3/00-H03F 19/00 (dynamo-electric amplifiers Fulltext... Hierarchy... Expanded...H02K)