FM-broadcast-receivable television tuner for preventing adjacent-channel interference
AssigneeAlps Electric Co., Ltd.
InventorMasaki Yamamoto
Life of this patent
Estimating the term…
Abstract
A trap circuit system includes a first trap portion and a second trap portion. In the first trap portion, a first capacitor is provided in parallel to a first switch diode. A control voltage is applied to the cathode of the first switch diode so as to change the trap frequency. In the second trap portion, a control voltage is applied to the cathode of a varactor diode so as to change the trap frequency. In the trap circuit system, when a television signal is received, the video intermediate frequency signal and the audio intermediate frequency signal in the lower adjacent channel are attenuated. When an FM broadcast signal is received, the video intermediate frequency signal and the chrominance subcarrier frequency signal are attenuated.
Claims5
A television tuner comprising:
- a mixer for receiving a television signal or an FM broadcast signal, and for converting the television signal to an intermediate frequency in a television intermediate frequency band and for converting the FM broadcast signal to an audio intermediate frequency in the television intermediate frequency band;
- an intermediate frequency amplifier provided at a stage subsequent to said mixer;
- and
- a trap circuit system provided at a stage subsequent to said intermediate frequency amplifier and configured to change a trap frequency,
- wherein the trap frequencies are positioned at a video intermediate frequency and an audio intermediate frequency in a lower adjacent channel when the television signal is received, and the trap frequencies are positioned at the video intermediate frequency and a chrominance subcarrier frequency when the FM broadcast signal is received.
Dependencies are inferred from the claim text.