| 摘要 |
An integrated circuit RF receiver (10) processes multiple RF frequencies without internally changing the local oscillator (18) to receive the multiple signals. No front-end tuner is used. In one embodiment, multiple crystals (22, 24) are connected to pins of the IC. A switch (26) within the IC, controlled by a switch signal (25), selects one of the crystals as a reference frequency, depending on the frequency of the RF signal desired to be received. The selected reference frequency is applied to an RF synthesizer (a local oscillator) to set the output frequency of the RF synthesizer (18). The local oscillator signal is then mixed with the incoming RF signal to generate sum and difference signals that need to be filtered by an IF filter (30). The switch signal (25) also reconfigures the IF filter (30) to change its center frequency and filter bandwidth, based on the requirements of the RF signal data format.
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