Abstract: The invention relates to a compensation circuit for filters of a video signal receiver. To compensate a non-linear amplification of a small signal in dependence upon the control of a large signal which is superimposed on the small signal, the invention proposes to detect the control of the large signal and to vary the working point of the filter in dependence upon the control of the large signal. Since the filter amplifies the small signal differently in dependence upon the position of the working point, the non-linearity of the filter can thereby be compensated.

Abstract: In order to provide a filter device (50, 60) as well as a method for processing input signals, in particular I[ntermediate]F[requency] input signals, for example sound signals, such as received television signals, wherein a bandpass function around the desired carriers is provided and the sound demodulation performance is not disturbed, at least one passive polyphase filter stage (50) being designed for image rejection and at least one active polyphase filter stage (60) being combined with the passive polyphase filter stage (50) and being designed for band pass as well as for contributing to the image rejection in order to relax the attenuation requirements of the passive polyphase filter stage (50) are proposed.

Abstract: In order to improve a circuit arrangement (100) and a method of controlling at least one transistor (10, 12, 14, 18), especially of controlling the resistance value of at least one MOS transistor with vanishing DC modulation in such a way that a compensation of resistance variations without control deviation is also possible for the case where the transistor (10, 12, 14, 18) is operated with a vanishing DC voltage, i.e.

Abstract: In order to improve a circuit arrangement (100) and a method of controlling at least one transistor (10, 12, 14, 18), especially of controlling the resistance value of at least one MOS transistor with vanishing DC modulation in such a way that a compensation of resistance variations without control deviation is also possible for the case where the transistor (10, 12, 14, 18) is operated with a vanishing DC voltage, i.e.

Abstract: A filter for processing frequency signals, preferably received, particularly digital television signals is described, which filter comprises a Chebyshev filter (11, 12), a subsequent all-pass filter (13) and a control device (14 to 20) for controlling the Chebyshev filter (11, 12) and the all-pass filter (13).

Abstract: The invention relates to a compensation circuit for filters of a video signal receiver. To compensate a non-linear amplification of a small signal in dependence upon the control of a large signal which is superimposed on the small signal, the invention proposes to detect the control of the large signal and to vary the working point of the filter in dependence upon the control of tile large signal. Since the filter amplifies the small signal differently in dependence upon the position of the working point, the non-linearity of the filter can thereby be compensated.

Abstract: A filter for processing frequency signals, preferably received, particularly digital television signals is described, which filter comprises a Chebyshev filter (11, 12), a subsequent all-pass filter (13) and a control device (14 to 20) for controlling the Chebyshev filter (11, 12) and the all-pass filter (13).

Abstract: For an optimal adjustment of the filter frequency of a signal filter, independently of external influences, process spreads and temperature fluctuations, a filter circuit for filtering at least one sound carrier in a composite video signal by at least one signal filter (24) having at least one filter frequency which is adjustable in dependence upon a control signal, is characterized in that the filter circuit (1) includes a reference filter (11) whose filter frequency is adjustable in dependence upon the control signal and which shifts the phase of a reference signal applied thereto by a defined value when tuning the filter frequency to the frequency of said reference signal, in that a phase comparator (14) is provided which receives the output signal of the reference filter (11) and the reference signal, in that the control signal is derived from the output signal of the phase comparator (14) in such a way that the reference filter (11) is tuned to the frequency of the reference signal, and in that an output

Abstract: For varying the filter frequencies in an integrator-filter circuit for filtering a push-pull signal by at least two integrator signal filters (31, 32, 33) having integrator elements (1), whose filter frequencies are adjustable by control currents (I.sub.n,1, I.sub.n,2) applied to the integrator elements (1), the integrator-filter circuit includes a reference integrator filter (38) having at least two integrator elements (1) constructed in an identical technique as the other integrator elements (1). This reference integrator filter, when tuned to the frequency of a test signal applied thereto, shifts the phase of the test signal by a defined value, and is arranged subsequent to a phase comparator (39) which also receives the test signal, so that a correction signal is derived from the output signal of the phase comparator (39), in dependence upon this correction signal. The control currents (I.sub.n,1, I.sub.

Abstract: To achieve a constant control range in an integrator-filter circuit for filtering a push-pull signal, having at least two integrator elements (1) this second control current being having resistors (11, 12) arranged at its inputs, a subsequent current multiplier (13) having two signal inputs (14, 15) and preceding a push-pull amplifier (18) with an inverting input (20) and a non-inverting input (19), having inverting output (21) fed back to the non-inverting input (19) and a non-inverting output (23) fed back to the inverting input (20) via capacitances (22, 24), the current multiplier (13) receiving, at two control inputs (37, 38), a first and a second control current (I.sub.1, I.sub.2) for adjusting the integration time constant of the integrator element (1) is adjustable and from which the second control current (I.sub.2) flows in substantially two halves through the signal inputs (14, 15) of the current multiplier (13), an associated third control current (I.sub.