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.

For arrangements combined with means for generating a controlling signal, or these means per se, see other main groups of H03G.

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.

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

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

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

Often a digital signal controls the gain.

The gain of amplifiers or frequency changers is controlled without distortion of the input signal. 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.

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

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.

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

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

The subject matter should be classified in the subgroups H03G 3/22–H03G 3/348 as appropriate.

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

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

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.

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 .

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.

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

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

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.

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.

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

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......

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.

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

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.

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 additionally classified into H03G 5/16, H03G 5/165 or H03G 5/18.

This subgroup covers the manual operation of the tone control.

This subgroup brings the automatic feature to the tone control.

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

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.

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.

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

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

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

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.

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.

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.

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 H03G 7/00 groups. Also soft clipping is classified in H03G 7/00 groups. The soft clipping is defined to be a form of compression.

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

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

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

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

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

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.