US 7,359,691 B2 · High frequency interference-cut filter circuit

Abstract

Disclosed is a high frequency apparatus which eliminates an influence of interfering signals. An interference-cut filter (24) for eliminating interfering signals is disposed between an input terminal (22) and a mixer (27). The interference-cut filter (24) is so controlled that it effectively demonstrates the function while the interfering signals are transmitted. Control of the interference-cut filter (24) is made by a switch (23), which is controlled by a selector switch controller (39), and the switch controller (39) is controlled responsive to an error correction counter (38) and a radio wave transmitted from a cellular telephone (40). This structure eliminates interference attributable to communication signals transmitted by the cellular telephone (40) and undesirable signals entering from the outside. The invention can thus realize high quality reception.

Claims8

Dependent claims

A high frequency apparatus comprising:

an input terminal for receiving a high frequency signal;
a mixer having an input port for receiving the signal fed through the input terminal, and another input port in connection to an output of a local oscillator;
an output terminal for delivering an output of the mixer;
an interference-cut filter disposed between the input terminal and the mixer for removing an interfering signal included in the high frequency signal;
a demodulator and an error correction circuit disposed in this order between the mixer and the output terminal;
and
an AGC voltage detector circuit in connection to an output of the mixer,
wherein the interference-cut filter is controlled when an interfering signal is transmitted,
wherein the interference-cut filter is controlled when a value of error correction signal output by the error correction circuit exceeds a predetermined value, and
wherein the interference-cut filter is controlled when an output of the AGC voltage detector circuit is within a predetermined voltage range.

7 more elements

Dependencies are inferred from the claim text.

High frequency interference-cut filter circuit

Life of this patent

High frequency interference-cut filter circuit

Life of this patent

Abstract

Claims8