초록 ▼

There is provided a highly reliable transmission/reception integrated radio-frequency apparatus which can achieve a high communication quality in a cable modem. A reception RF signal is input to a reception system block via an input/output terminal, converted to an intermediate-frequency signal, and

There is provided a highly reliable transmission/reception integrated radio-frequency apparatus which can achieve a high communication quality in a cable modem. A reception RF signal is input to a reception system block via an input/output terminal, converted to an intermediate-frequency signal, and output from a terminal. An output terminal of a transmission processing section of a transmission system block is connected to the input/output terminal via an overvoltage protection circuit, a high-pass filter functioning as a countermeasure to overvoltage, and a low-pass filter for suppressing harmonics produced from the high-pass filter.

대표청구항 ▼

What is claimed is: 1. A transmission/reception integrated radio-frequency apparatus comprising, an input/output terminal for inputting/outputting of a radio-frequency signal; a reception system block for processing a reception radio-frequency signal supplied to the input/output terminal; a transmi

What is claimed is: 1. A transmission/reception integrated radio-frequency apparatus comprising, an input/output terminal for inputting/outputting of a radio-frequency signal; a reception system block for processing a reception radio-frequency signal supplied to the input/output terminal; a transmission processing section including a semiconductor element for outputting a transmission radio-frequency signal to the input/output terminal; a first high-pass filter connected between the reception system block and the input/output terminal and having a first cut-off frequency (lower-limit frequency) less than a lower-limit frequency of reception frequencies; a second high-pass filter connected to an output terminal of the transmission processing section and having a second cut-off frequency (lower-limit frequency) in a frequency band lower than said first cut-off frequency; a low-pass filter connected between the second high-pass filter and the input/output terminal and having a cut-off frequency (upper-limit frequency) in a frequency band which is higher than said second cut-off frequency and tower than said first cut-off frequency; and an overvoltage breakdown protection circuit connected between the output terminal of the transmission processing section and the second high-pass filter. 2. A transmission/reception integrated radio-frequency apparatus according to claim 1, wherein said overvoltage breakdown protection circuit comprises two zener diodes connected in series between a signal line and a ground, and electrodes of the two zener diodes, which have the same polarities (cathodes or anodes), are connected to each other. 3. A transmission/reception integrated radio-frequency apparatus according to claim 1, wherein said overvoltage breakdown protection circuit comprises a first series circuit and a second series circuit, each of the first and second series circuits comprising a zener diode and a diode having a higher reverse breakdown voltage than the zener diode, with their electrodes of the same polarities (cathodes or anodes) being connected to each other, and the first and second series circuits are connected in parallel between a signal line and a ground such that the polarity of the zener diode of the first series circuit is opposite to the polarity of the zener diode of the second series circuit, and the polarity of the diode of the first series circuit is opposite to the polarity of the diode of the second series circuit.