Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements

Introduced: September 1968

Of 22 combined children, 20 exist in both systems.

1 codes are CPC-only extensions, 1 exist only in IPC.

7 shared codes have differing titles between IPC and CPC.

Child Classifications

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H03F 3/005 CPC only CPC only
H03F 3/02 with tubes only IPC+CPC Available in IPC and CPC
H03F 3/04 with semiconductor devices only IPC+CPC Available in IPC and CPC
H03F 3/18 with semiconductor devices of complementary types IPC only IPC only
H03F 3/181 Low-frequency amplifiers, e.g. audio preamplifiers since 1974 IPC+CPC Available in IPC and CPC
H03F 3/189 High-frequency amplifiers, e.g. radio frequency amplifiers since 1974 IPC+CPC Available in IPC and CPC
H03F 3/20 Power amplifiers, e.g. Class B amplifiers, Class C amplifiers (H03F3/26 - H03F3/30 take precedence) IPC+CPC Available in IPC and CPC
H03F 3/26 Push-pull amplifiers; Phase-splitters therefor (duplicated single-ended push-pull arrangements or phase-splitters therefor H03F3/30) +1 CPC IPC+CPC Available in IPC and CPC
H03F 3/30 Single-ended push-pull amplifiers ; Phase-splitters therefor +5 CPC −1 IPC IPC+CPC Available in IPC and CPC
H03F 3/34 DC amplifiers in which all stages are DC-coupled (H03F3/45 takes precedence) IPC+CPC Available in IPC and CPC
H03F 3/38 DC amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers IPC+CPC Available in IPC and CPC
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 +2 CPC IPC+CPC Available in IPC and CPC
H03F 3/45 Differential amplifiers (differential sense amplifiers G11C7/062) since 1974 +1 CPC IPC+CPC Available in IPC and CPC
H03F 3/46 Reflex amplifiers IPC+CPC Available in IPC and CPC
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 +1 CPC IPC+CPC Available in IPC and CPC
H03F 3/54 Amplifiers using transit-time effect in tubes or semiconductor devices (parametric amplifiers H03F7/00; solid state travelling-wave devices H10N70/10) IPC+CPC Available in IPC and CPC
H03F 3/60 Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators (H03F3/54 takes precedence) +4 CPC IPC+CPC Available in IPC and CPC
H03F 3/62 Two-way amplifiers IPC+CPC Available in IPC and CPC
H03F 3/66 Amplifiers simultaneously generating oscillations of one frequency and amplifying signals of another frequency IPC+CPC Available in IPC and CPC
H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics IPC+CPC Available in IPC and CPC