Variable band-pass filter circuit
AssigneeSanyo Electric Co., Ltd.
InventorHiroshi Nomura
Life of this patent
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Abstract
A variable band-pass filter circuit includes a variable band-pass filter which filters an input signal such as a chrominance signal. An output the variable band-pass filter is phase-compared with a reference signal in a phase comparator. An output of the phase comparator is applied to the variable band-pass filter as a control signal. The output of the variable band-pass filter is level-limited by a limiter and then applied to an adder which further receives the reference signal. One of the input signal and an output of the adder is selected by a switch to be applied to an input of the variable band-pass filter. A reference signal component is removed by the sample hold circuit to be prevented from being outputted from an output of the variable ban-pass filter.
Claims4
A variable band-pass filter circuit, comprising:
- a first variable band-pass filter;
- reference signal applying means for applying a reference signal;
- phase-comparing means for phase-comparing an output signal of said first variable band-pass filter with said reference signal to output a control signal for controlling said first variable band-pass filter;
- level limiting means for receiving said output signal from said first variable band-pass filter;
- adding means for adding an output from said level limiting means and said reference signal to each other so as to apply the same to an input of said first variable band-pass filter;
- and
- a first switch which is controlled by a switching signal in a first state wherein an input signal to be filtered by said variable band-pass filter circuit is applied to said input of said first variable band-pass filter through said first switch or in a second state wherein an output of said adding means is applied to said input of said first variable band-pass filter through said switch.
Dependencies are inferred from the claim text.