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CONTROL OF AMPLIFICATION (impedance networks, e.g. attenuators, H03H; control of transmission in lines H04B 3/04)
Definition statement
This subclass/group covers:
  • Control of gain of amplifiers or frequency-changers
  • Control of frequency range of amplifiers
  • Limiting amplitude or rate of change of amplitude
References relevant to classification in this subclass
This subclass/group does not cover:
Amplifiers per se , including:Linear amplification, there being linear relationship between the amplitudes of input and output, and the output having substantially the same waveform as the input Dielectric amplifiers, magnetic amplifiers, and parametric amplifiers when used as oscillators or frequency-changersConstructions of active elements of dielectric amplifiers and parametric amplifiers if no provision exists elsewhere
Details of arrangements for controlling amplification [N: for arrangements combined with means for generating a controlling signal, or these means per se, see the other main groups of H03G]
Definition statement
This subclass/group covers:

Details of gain control loops. The invention can be found in the details. This is opposite to control systems in which the total system, including the loop, is the invention.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Cascode amplifiers
Differential amplifiers
Resistor networks
[N: in emitter-coupled or cascode amplifiers (H03G 1/0029 takes precedence)]
Definition statement
This subclass/group covers:

This is an important subgroup , including the emitter-coupled or cascode amplifiers. In these amplifiers the gain is changed by e.g. a controlled resistor between coupled emitters.

[N: using FETs]
Definition statement
This subclass/group covers:

The subgroup H03G 1/0029 takes precedence and includes the same structures as H03G 1/0023 but uses FETs instead of bipolar transistors.

[N: using continuously variable impedance elements]
Definition statement
This subclass/group covers:

This subgroup includes continuously variable elements that change the gain in a continuous manner. The control signal is an analogue signal.

[N: using discontinuously variable devices, e.g. switch-operated]
Definition statement
This subclass/group covers:

This subgroup includes discontinuously variable elements that change the gain. Discontinuously variable elements change the gain stepwise.

Often a digital signal controls the gain.

Gain control in amplifiers or frequency changers [N: without distortion of the input signal] (gated amplifiers H03F 3/72; peculiar to television receivers H04N)
Definition statement
This subclass/group covers:

The gain of amplifiers or frequency changers is controlled. The main concept of controlling is the feedback loop from the output of the amplifier to a controlling element. Other gain control concepts are possible.

References relevant to classification in this main group
This subclass/group does not cover:
Modifications of amplifiers to reduce non-linear distortion
Details of transmission systems for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver
Arrangements for compensation undesirable properties of the transmission path between the modulator and demodulator using predistortion
Details of television systems, automatic gain control in receiver circuitry of TVs
Transmission Power control whereby these systems are bidirectionally controlled . In these systems the transmitter gets the gain information from the receiver.
Informative references
Attention is drawn to the following places, which may be of interest for search:
Amplitude control for seismic recording
Speech amplifiers in telephones
Hearing aids
Digital control of analog signals
Definition statement
This subclass/group covers:

This subgroup includes important details of the digital domain used for controlling an analogue signal; e.g. multiplying DACs.

[N: Control of digital or coded signals (H03G 3/3089 take precedence)]
Definition statement
This subclass/group covers:

In this subgroup mathematical methods in the digital domain are included. In this subgroup, either the control loop is not described in the description, or parts of the amplifier are very detailed.

Manually-operated control [N: H03G 3/001 and H03G 3/002 take precedence]
Definition statement
This subclass/group covers:

In this subgroup the amplification is manually controlled; e.g.buttons or sliders are included to be used by a person

Automatic control ([N: H03G 3/005 takes precedence]; combined with volume compression or expansion H03G 7/00)
Definition statement
This subclass/group covers:

This is a heading subgroup for the further automatic control subgroups.

The gain of amplifiers is controlled with an automatic system. The main automatic concept for controlling is the feedback loop from the output of the amplifier to a controlling element.

Most systems are classified in the following classes

in amplifiers having semiconductor devices
Definition statement
This subclass/group covers:

This is a heading subgroup for the further automatic control subgroups having semiconductor devices.

This group is also used when the amplifiers are not further described and either presented in functional blocks or just obviously have semiconductor devices. Most systems are classified in the following classes

[N: in amplifiers suitable for low-frequencies,e.g. audio amplifiers (H03G 3/32,H03G 3/34 take precedence)]
Definition statement
This subclass/group covers:

In this subgroup analogue and digital audio systems are included. Digital audio systems should additionally be classified in H03G 3/3089.

[N: in high-frequency amplifiers or in frequency changers (H03G 3/3052, H03G 3/32, H03G 3/34 take precedence)]
Definition statement
This subclass/group covers:

This subgroup specially includes AGCs in high frequency amplifiers e.g., pre amplifiers

If the AGC is used in transmitters or if the AGC is used in power amplifiers, they are classified in the following sub groups.

[N: in modulators, frequency-changers, transmitters or power amplifiers]
Definition statement
This subclass/group covers:

In this subgroup many examples of controlling the gain in amplifiers in transmitters e.g. in base stations, mobile phones, WLAN, and power amplifiers are included .

[N: for intermittent signals, e.g. burst signals]
Definition statement
This subclass/group covers:

Circuits to control the burst of the transmission signal.In this subgroup many examples for controlling amplifiers in transmitters e.g. in base stations, mobile phones, WLAN, and power amplifiers are included.

This subgroup is used if the burst is important for controlling the amplification.

[N: in band pass amplifiers (H.F. or I.F.) or in frequency-changers used in a super)heterodyne receiver (H03G 3/32, H03G 3/34 take precedence)]
Definition statement
This subclass/group covers:

This subgroup is a heading subgroup for controlling the amplification of receivers and band pass amplifiers.

[N: using at least one diode as controlling device]
Definition statement
This subclass/group covers:

This subgroup includes many amplifiers in RECEIVERS (mobile phones, WLAN....). This subgroup is used if especially a diode is important as controlling element.

[N: using at least one transistor as controlling device, the transistor being used as a variable impedance device]
Definition statement
This subclass/group covers:

This subgroup includes many amplifiers in RECEIVERS (mobile phones, WLAN....). This subgroup is used if it is important that at least one transistor is used as controlling element.

[N: Circuits generating control signals for both R.F. and I.F. stages]
Definition statement
This subclass/group covers:

This subgroup includes many amplifiers in RECEIVERS (mobile phones, WLAN....). This subgroup is used if both R.F. stages and I.F. stages are controlled.

[N: Circuits generating control signals when no carrier is present, or in SSB, CW or pulse receivers]
Definition statement
This subclass/group covers:

This subgroup includes receivers. This subgroup is e.g. used if the pulse is important for controlling the gain.

[N: Circuits generating control signals for digitally modulated signals]
Definition statement
This subclass/group covers:

This subgroup includes many amplifiers in RECEIVERS (mobile phones, WLAN....)

This subgroup includes most of the modern receivers, since they are based on digital modulation, e.g. OFDM......

[N: Control of digital or coded signals]
Definition statement
This subclass/group covers:

This subgroup includes many digital audio systems. Digital audio systems should additionally be classified in H03G 3/3005 or attached sub groups.

This subgroup is also used for digital hf systems.

the control being dependent upon ambient noise level or sound level
Definition statement
This subclass/group covers:

This subgroup includes many audio systems , whereby the noise signal is important for controlling the volume. These systems are often used in cars.

Tone control or bandwidth control in amplifiers
Definition statement
This subclass/group covers:

This main group mainly consists of audio amplifiers. The characteristic of an audio signal is changed, so that the sound of the signal is changed. This is the function of tone control. The second possibility is bandwidth control, which includes also the control of high frequency bandwidth.

References relevant to classification in this main group
This subclass/group does not cover:
Impedance networks, e.g. resonant circuits, resonators, frequency selective filters
Control of transmission, equalising in line transmission systems
Modulated carrier systems; equalisers for modulated carrier systems
Informative references
Attention is drawn to the following places, which may be of interest for search:
Hearing aids
Control circuits for electronic adaptation of the sound field
[N: of digital signals]
Definition statement
This subclass/group covers:

Modern audio systems are mostly digital systems. This subgroup mainly includes the digital tone control systems.

If the system is a digital audio system it should be put additionally into H03G 5/16, H03G 5/165 or H03G 5/18.

Manually-operated control
Definition statement
This subclass/group covers:

In former years, tone control was mainly dominated by manual operation. Also today, the manual input is sometimes the important part of the device. This subgroup covers the manual operation of the tone control.

Automatic control
Definition statement
This subclass/group covers:

This subgroup brings the automatic feature to the tone control.

[N: Equalizers; Volume or gain control in limited frequency bands]
Definition statement
This subclass/group covers:

This subgroup contains equalizers. The audio signal is divided into different bands and the bands are treated separately. Digital audio equalizers should also be classified in H03G 5/005

Volume compression or expansion in amplifiers [N: frequency dependent H03G 9/00]
Definition statement
This subclass/group covers:

This main group mainly consists of audio amplifiers.

The controlling is independent of frequency. This main group includes: soft limiting, soft clipping, logarithmic amplifiers, and includes also: gain control which is linear in dB, Dolby compression.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Logarithmic function generators
Hearing aids

[N: without controlling loop (H03G 7/007, H03G 7/02, H03G 7/06 take precedence)]

Definition statement
This subclass/group covers:

This subgroup includes also limiting amplifiers, logarithmic amplifiers (also high frequency amplifiers) . In this context the controlling loop from the output of the system to the amplifier is missing. This results in that no strong time delay is present in the controlling.

[N: in untuned or low-frequency amplifiers e.g. audio amplifiers (H03G 7/007, H03G 7/001, H03G 7/008, H03G 7/02, H03G 7/06 take precedence)]
Definition statement
This subclass/group covers:

This subgroup mainly consists of audio amplifiers.

The controlling is independent of frequency.

This subclass also includes systems, if the audio system is only presented in the application in the form of functional blocks.

If the system is a digital audio system it should be put into H03G 7/002 and H03G 7/007

[N: of digital or coded signals]
Definition statement
This subclass/group covers:

Modern audio systems are mostly digital systems. This subgroup mainly includes the digital volume compression and expansion systems.

If the system is a digital audio system it should be put into H03G 7/002 and H03G 7/007

Combinations of two or more types of control, e.g. gain control and tone control
Definition statement
This subclass/group covers:

This main group mainly consists of audio amplifiers. At least two types of controlling are combined into one invention.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Hearing aids
Control circuits for the electronic adaptation of the sound field
[N: of digital or coded signals]
Definition statement
This subclass/group covers:

Modern audio systems are mostly digital systems. This subgroup includes the digital systems in which at least two types of controlling are combined into one invention.

This subgroup contains many psycho-acoustic systems.

in untuned amplifiers (combined tone controls for low and high frequencies H03G 5/00) [N: compression or expansion combined with volume control H03G 7/00]
Definition statement
This subclass/group covers:

This subgroup mainly consists of audio amplifiers. At least two types of controlling are combined into one invention.

This subclass also includes applications, where the audio system is only presented in the application in the form of functional blocks.

[N: frequency-dependent volume compression or expansion, e.g. multiple-band systems (H03G 9/10, H03G 9/18 take precedence)]
Definition statement
This subclass/group covers:

This sub group mainly consists of audio amplifiers. This subgroup contains frequency-dependent volume compression or expansion.

This subclass also includes applications, where the audio system is only presented in the application in the form of functional blocks.

This subgroup includes many psycho-acoustic systems.

Limiting amplitude; Limiting rate of change of amplitude; [N: Clipping in general]
Definition statement
This subclass/group covers:

This main group covers clipping systems. Clipping is defined to include a hard cut. If the amplitude is limited in a soft way, this is defined to be compression. Compression is classified in H03G7 groups. Also soft clipping is classified in H03G7 groups. The soft clipping is defined to be a form of compression.

References relevant to classification in this main group
This subclass/group does not cover:
Volume/level/amplitude compression
[N: without controlling loop (H03G 11/004, H03G 11/006, H03G 11/008, H03G 11/02, H03G 11/04, H03G 11/06, H03G 11/08 take precedence; ]
Definition statement
This subclass/group covers:

This subgroup includes clipping systems without feedback loop. As no feedback loop is used, the systems have no delays, and no over swinging.

[N: of digital or coded signals]
Definition statement
This subclass/group covers:

Modern audio systems are mostly digital systems. This subgroup includes the digital systems which clip the audio signal in a hard way.

by means of diodes ([N: H03G 11/008,] H03G 11/04, H03G 11/06, H03G 11/08 take precedence)
Definition statement
This subclass/group covers:

This subgroup includes inventions where the diode is the important element for clipping.

Limiting level dependent on strength of signal; Limiting level dependent on strength of carrier on which signal is modulated [N: H03G 11/008 takes precedence]
Definition statement
This subclass/group covers:

This subgroup includes inventions where the strength of a signal is the important factor to define the clipping level.

Limiting rate of change of amplitude [N: H03G 11/008 takes precedence]
Definition statement
This subclass/group covers:

This subgroup includes inventions where the rate of change of a signal is limited.

Subject matter not provided for in other groups of this subclass
Definition statement
This subclass/group covers:

Control of amplification not covered elsewhere in H03G.

H03G 1/00 contains details of the arrangement for controlling.

H03G 99/00 is defined to include applications which could not be placed in an other main /subgroup. This main group is mainly created for organizational reasons. Usually it should be empty.

References relevant to classification in this main group
This subclass/group does not cover:

Places in relation to which this main group is residual:

Details of arrangements for controlling amplification
Gain control in amplifiers or frequency changers
Tone control or bandwidth control in amplifiers
Volume compression or expansion in amplifiers
Combinations of two or more types of control, e.g. gain control and tone control
Limiting amplitude; Limiting rate of change of amplitude
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Last Modified: 10/11/2013