|  | H |
SECTION H — ELECTRICITY

|  | H03 |
BASIC ELECTRONIC CIRCUITRY

|  | H03F |
AMPLIFIERS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; optical parametric amplifiers Fulltext... Hierarchy... Expanded...G02F; circuit arrangements with secondary emission tubes Fulltext... Hierarchy... Expanded...H01J 43/30; masers, lasers Fulltext... Hierarchy... Expanded...H01S; control of amplification Fulltext... Hierarchy... Expanded...H03G; coupling arrangements independent of the nature of the amplifier, voltage dividers Fulltext... Hierarchy... Expanded...H03H; amplifiers capable only of dealing with pulses Fulltext... Hierarchy... Expanded...H03K; repeater circuits in transmission lines Fulltext... Hierarchy... Expanded...H04B 3/36, Fulltext... Hierarchy... Expanded...H04B 3/58; application of speech amplifiers in telephonic communication Fulltext... Hierarchy... Expanded...H04M 1/60, Fulltext... Hierarchy... Expanded...H04M 3/40)

|  | 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, only semiconductor devices or only unspecified 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; to raise the efficiency of amplifiers acting also as modulators [2]

|  | H03F 1/07 |
· · · · | Doherty-type amplifiers [2]

|  | H03F 1/08 |
· | Modification of amplifiers to reduce detrimental influences of internal impedances of amplifying elements (wide-band amplifiers with inter-stage coupling networks incorporating these impedances Fulltext... Hierarchy... Expanded...H03F 1/42; eliminating transit-time effects in vacuum tubes Fulltext... Hierarchy... Expanded...H01J 21/34)

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

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

|  | H03F 1/13 |
· · · | in discharge-tube amplifiers [2]

|  | 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

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

|  | H03F 1/33 |
· · | in discharge-tube amplifiers [2]

|  | H03F 1/34 |
· | Negative-feedback-circuit arrangements with or without positive feedback (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03F 1/02-H03F 1/30, Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03F 1/38-H03F 1/50, Fulltext... Hierarchy... Expanded...H03F 3/50 take precedence)

|  | 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 1/52 |
· | Circuit arrangements for protecting such amplifiers [3]

|  | H03F 1/54 |
· · | with tubes only [3]

|  | H03F 1/56 |
· | Modifications of input or output impedances, not otherwise provided for [3]

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

|  | H03F 3/02 - H03F 3/195 |
Note(s) Groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03F 3/20-H03F 3/72 take precedence over groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03F 3/02-H03F 3/195. [2]

|  | 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 3/181 |
· | Low-frequency amplifiers, e.g. audio preamplifiers [2]

|  | H03F 3/183 |
· · | with semiconductor devices only [2]

|  | H03F 3/185 |
· · · | with field-effect devices (Fulltext... Hierarchy... Expanded...H03F 3/187 takes precedence) [2]

|  | H03F 3/187 |
· · · | in integrated circuits [2]

|  | H03F 3/189 |
· | High-frequency amplifiers, e.g. radio frequency amplifiers [2]

|  | H03F 3/19 |
· · | with semiconductor devices only [2]

|  | H03F 3/191 |
· · · | Tuned amplifiers (Fulltext... Hierarchy... Expanded...H03F 3/193, Fulltext... Hierarchy... Expanded...H03F 3/195 take precedence) [2]

|  | H03F 3/193 |
· · · | with field-effect devices (Fulltext... Hierarchy... Expanded...H03F 3/195 takes precedence) [2]

|  | H03F 3/195 |
· · · | in integrated circuits [2]

|  | 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 3/21 |
· · | with semiconductor devices only [2]

|  | H03F 3/213 |
· · · | in integrated circuits [2]

|  | H03F 3/217 |
· · · | Class D power amplifiers; Switching amplifiers [2]

|  | 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 (Fulltext... Hierarchy... Expanded...H03F 3/45 takes precedence)

|  | H03F 3/343 |
· · | with semiconductor devices only [2]

|  | H03F 3/345 |
· · · | with field-effect devices (Fulltext... Hierarchy... Expanded...H03F 3/347 takes precedence) [2]

|  | H03F 3/347 |
· · · | in integrated circuits [2]

|  | 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; amplitude modulation of pulses in general Fulltext... Hierarchy... Expanded...H03K 7/02; amplitude demodulation of pulses in general Fulltext... Hierarchy... Expanded...H03K 9/02)

|  | H03F 3/387 |
· · | with semiconductor devices only [2]

|  | H03F 3/393 |
· · · | with field-effect devices [2]

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

|  | H03F 3/42 |
· | Amplifiers with two or more amplifying elements having their dc paths in series with the load, 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 3/45 |
· | Differential amplifiers [2]

|  | 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 or semiconductor devices (parametric amplifiers Fulltext... Hierarchy... Expanded...H03F 7/00; solid state travelling-wave devices Fulltext... Hierarchy... Expanded...H01L 45/02)

|  | H03F 3/55 |
· · | with semiconductor devices only [2]

|  | 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 3/70 |
· | Charge amplifiers [2]

|  | H03F 3/72 |
· | Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal [2]

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

|  | H03F 7/00 |
Parametric amplifiers (parametric generation or amplification of light, infra-red or ultra-violet waves Fulltext... Hierarchy... Expanded...G02F 1/39)

|  | 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 9/02 |
· | Current-controlled, i.e. the load current flowing in both directions through a main coil [2]

|  | H03F 9/04 |
· | Voltage-controlled, i.e. the load current flowing in only one direction through a main coil, e.g. Logan circuits (Fulltext... Hierarchy... Expanded...H03F 9/06 takes precedence) [2]

|  | H03F 9/06 |
· | Control by voltage time integral, i.e. the load current flowing in only one direction through a main coil, whereby the main coil winding also can be used as a control winding, e.g. Ramey circuits [2]

|  | 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)