Dynamic noise suppression circuit

摘要

The invention relates to radio and audio systems and concerns in particular a dynamic noise suppression circuit. The dynamic noise suppression circuit contains an adjustable main low-pass filter (1) which has a series circuit comprising field effect transistors (2, 6), an active element (10) and a control unit (11) which is connected to the field effect transistors (2, 6). The control unit (11) has a series circuit comprising an algebraic adder (22), a weighted filter (23), a minimum value limiter (24), a frequency corrector (25) and an amplitude detector (28). The dynamic noise suppression circuit also contains an additional adjustable high-pass filter (14) which has a series circuit comprising an external capacitor (19) and a field effect transistor (15) which is connected to the field effect transistors (2, 6) and the algebraic adder (22). The dynamic noise suppression circuit contains an amplitude detector (29) which is connected to an amplifier (27) of the frequency corrector (25), a regulator (33) for the final value of the passband, a fixer (32) for the final value of the passband and a control current source (34). The output of the regulator (33) is coupled with the inputs of the amplitude detectors (28, 29) and the fixer (32). The invention can be used in different audio system and audio reproduction devices. <IMAGE>