Circuit arrangement for amplitude-dependent attenuation of a television signal
AssigneeU.S. Philips Corporation
InventorMatthias Peters
Life of this patent
Estimating the term…
Loading patent…
AssigneeU.S. Philips Corporation
InventorMatthias Peters
Estimating the term…
A circuit arrangement for amplitude-dependent attenuation of a television signal supplies amplitude values below a predeterminable limit value as an output signal amplified by a first gain factor, and, at amplitude values above the limit value, supplies the part of the amplitude below the limit value as an output signal amplified by the first gain factor and parts of the amplitude above the limit value as an output signal amplified by a second gain factor, the second gain factor being chosen to be smaller than the first gain factor. To realize this circuit arrangement in the current range, the television signal is a current signal which is applied to a main branch (1; 13) and a sub-branch (2; 14) in which the current signal is applied to the emitter of at least one transistor (3,5; 15,18) via a resistor (4,6; 16,19), the base of each transistor (3,5; 15,18) is biased with respect to a reference potential by DC sources (7,8; 17,24), the collector current of the transistor (3; 15) in the main branch (1; 13) essentially represents the output signal, and the limit value is predeterminable by the difference between the base potentials of the two transistors (3,5; 15,18) and the second gain factor is predeterminable by means of the resistance ratio between the two resistors (4,6; 16,19).
A circuit arrangement for amplitude-dependent attenuation of a television signal, said arrangement supplying amplitude values of the television signal below a predeterminable limit value as an output signal amplified by a first gain factor, and, at amplitude values above the predeterminable limit value, supplying a part of the amplitude below the predeterminable limit value as an output signal amplified by the first gain factor and parts of the amplitude above the predeterminable limit value as an output signal amplified by a second gain factor, the second gain factor being chosen to be smaller than the first gain factor, characterized in that the television signal is a current signal which is applied to a main branch and a sub-branch in which said main branch and said sub-branch each comprises at least one transistor, said current signal being applied to an emitter of said at least one transistor via a resistor in each of said main branch and said sub-branch, a base of said at least one transistor in each of said main branch and said sub-branch being biased, with respect to a reference potential, by respective DC sources, a collector current of the at least one transistor in the main branch essentially representing the output signal, and the predeterminable limit value being predetermined by a difference between base potentials of the at least one transistors in the main branch and the sub-branch and the second gain factor being determined by a resistance ratio between the resistors coupled to the emitters of said at least one transistors in said main branch and said sub-branch.
Dependencies are inferred from the claim text.