H03F3/1855 - CPC Classification Index

ClassID:

219221 ⎘

H03F3/1855 - CPC Classification

Classification description:

Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements; Low frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only with field-effect devices with junction-FET devices

Recent Application in this class:

20260089420

2026-03-26

MICROPHONE FOR CAPTURING SOUND

20260066857

2026-03-05

METHODS AND APPARATUS TO REGULATE AN AMPLIFIER

20260066856

2026-03-05

METHODS AND APPARATUS TO REGULATE AN AMPLIFIER

20230261617

2023-08-17

Pre-amplification conditioning circuit for a transducer audio device

20230246604

2023-08-03

Pre-amplification conditioning circuit for a transducer audio device

20230089860

2023-03-23

Musical instrument preamplifier

20220385253

2022-12-01

Valve amplifiers

20210250008

2021-08-12

Charge amplifier circuit for high-temperature piezoelectric transducers

20180375482

2018-12-27

ADAPTIVE-SNR ULTRA-LOW-POWER ULTRA-LOW-NOISE MICROPHONE

#10

20180206043

2018-07-19

AN ULTRA-LOW-POWER ULTRA-LOW-NOISE MICROPHONE

#11

20150365059

2015-12-17

Class-D amplifier and electronic apparatus

#12

20150010171

2015-01-08

Circuit for use with a loudspeaker for portable equipments

#13

20140294204

2014-10-02

Audio amplifier mode transition

#14

20130108081

2013-05-02

Amplifier using voltage variable power supply

#15

20090245543

2009-10-01

Amplifying element and manufacturing method thereof

#16

20050146389

2005-07-07

Split cascode line amplifier for current-mode signal transmission