Adjacent channel optimized receiver
The present invention offers significant improvements in the performance of a radio receiver operating in an environment with high desired band interference. The present invention comprises a high selectivity RF circuit that is located between the antenna and the radio receiver, and utilizes superheterodyne technology to filter adjacent channel interference in the desired band frequency spectrum. This type of interference is problematic for IEEE 802.11 radio receivers that are implemented with the popular direct conversion radio receiver architectures. The present invention may be utilized in many types of radio receivers.
1. A device comprising:
a radio frequency (RF) convertor operative to receive a first RF signal and generate a second RF signal;
a programmable oscillator, coupled to the RF convertor, said programmable oscillator operative to control the second RF signal in response to a oscillator control signal;
one or more channel select switches coupled to a plurality of filters, said switches operative to direct the second RF signal to at least one of said filters in response to a channel select signal;
one or more programmable band select filters, said band select filters operative to select an RF band in response to a band select signal;
a receiver operative to receive an RF signal and generate the oscillator, channel select and band select signals,
wherein the oscillator control signal and the channel select signal operate to select a second RF signal and filters to minimize adjacent channel interference.
2. The device of claim 1 further including:
a second RF convertor coupled to the programmable oscillator and operative to receive the second RF signal and convert it to a different frequency.
3. The device of claim 1 wherein the channel select signal comprises bandwidth information of a desired channel.
4. The device of claim 1 wherein the filters are SAW filters.
5. The device of claim 1 wherein the filters comprise filters that have bandwidths whose values are substantially equal to 5, 10, 20, and 40 MHz and have a center frequency that is substantially equal to the second RF signal.