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An RF receiving circuit that selectively attenuates a received RF signal before it reaches sensitive modifying devices, such as a low noise amplifier or an analog to digital converter. The receiving circuit includes a delay element upstream of its attenuator so that high energy pulses of a short dur

An RF receiving circuit that selectively attenuates a received RF signal before it reaches sensitive modifying devices, such as a low noise amplifier or an analog to digital converter. The receiving circuit includes a delay element upstream of its attenuator so that high energy pulses of a short duration (for example, less than 10 nanoseconds) can be effectively attenuated despite coupler, detector, threshold and/or switch delays of the attenuation related circuitry.

대표청구항 ▼

What is claimed is: 1. An RF receiver circuit comprising: an antenna adapted to produce an RF signal in response to electromagnetic waves; a delay element directly electrically connected to said antenna so that said delay element receives and delays the RF signal from said antenna; a PRD electrical

What is claimed is: 1. An RF receiver circuit comprising: an antenna adapted to produce an RF signal in response to electromagnetic waves; a delay element directly electrically connected to said antenna so that said delay element receives and delays the RF signal from said antenna; a PRD electrically connected to said delay element so that said PRD receives the delayed RF signal from said delay element and selectively reduces the power of the RF signal; and a modifying device electrically connected to said PRD so that said modifying device receives the RF signal from said PRD. 2. The circuit of claim 1 further comprising a PRD controller electrically connected to said antenna and adapted to control the power reduction operation of said PRD based on the power of the RF signal received from said antenna. 3. The circuit of claim 2 wherein: said PRD is characterized by a PRD delay; said PRD controller is characterized by a PRD controller delay; and the delay caused by said delay element is approximately equal to the sum of the PRD delay and the PRD controller delay. 4. The circuit of claim 2 wherein said PRD comprises RF switches. 5. The circuit of claim 4 wherein said PRD controller comprises a tunnel diode detector and an RF switch controller amplifier. 6. The circuit of claim 2 wherein said PRD controller comprises a coupler and is electrically connected to the antenna through the coupler. 7. The circuit of claim 1 wherein said modifying device is an LNA. 8. The circuit of claim 1 wherein said modifying device is an analog to digital converter. 9. An RF receiver circuit comprising: an antenna adapted to produce an RF signal in response to electromagnetic waves; a delay element directly electrically connected to said antenna so that said delay element receives and delays the RF signal from said antenna; at least one RF switch(es) electrically connected to said delay element so that said RF switch(es) receive the delayed RF signal from said delay element and selectively attenuate the RF signal; an RF switch controller electrically connected to said antenna and adapted to control the attenuation operation of said RF switch(es) based on the power of the RF signal received from said antenna, with said RF switch controller comprising a tunnel diode detector and a resistor, with said tunnel diode detector and said resistor being electrically connected in parallel; a coupler adapted and connected to electrically connect said RF switch controller to the antenna so that said RF switch controller receives the RF signal from said antenna; and a modifying device electrically connected to said RF switches so that said modifying device receives the attenuated RF signal from said RF switches. 10. The circuit of claim 9 wherein said RF switch controller further comprises a capacitor connected in parallel with both said resistor and said tunnel diode detector. 11. The circuit of claim 9 wherein said RF switch controller further comprises a capacitor connected in series with said resistor and in parallel with said tunnel diode detector. 12. The circuit of claim 9 wherein said RF switch controller further comprises an RF switch controller amplifier. 13. The circuit of claim 9 wherein: said RF switches are characterized by an RF switch delay; said RF switch controller and said coupler are characterized by an RF switch controller delay; and the delay caused by the delay element is approximately equal to a sum of the RF switch delay and the RF switch controller delay. 14. The circuit of claim 9 wherein the delay element comprises a transmission line. 15. The circuit of claim 9 wherein said delay element comprises a delay filter. 16. The circuit of claim 9 wherein said delay element is adapted to cause a delay of less than 10 nanoseconds. 17. The circuit according to claim 9 further comprising an RF radiation source located and adapted to generate the electromagnetic waves received by the antenna. 18. The circuit of claim 17 wherein said RF radiation source generates the RF radiation in the form of pulses of less than 10 nanoseconds in duration. 19. The circuit of claim 9 wherein the RF signal has a frequency of greater than 300 MHz. 20. A radar device comprising: an RF radiation source adapted to generate electromagnetic radar waves having a pulse time of less than 10 nanoseconds and a frequency of greater than 300 MHz; an antenna adapted and located to receive the radar waves and to produce an RF signal in response to the electromagnetic waves; a delay element directly electrically connected to said antenna so that said delay element receives and delays the RF signal from said antenna; at least one RF switch(es) electrically connected to said delay element so that said RF switch(es) receive the delayed RF signal from said delay element and selectively attenuate the RF signal; an RF switch controller electrically connected to said antenna and adapted to control the attenuation operation of said RF switch(es) based on the power of the RF signal received from said antenna, with said RF switch controller comprising: a tunnel diode detector, a resistor, with said tunnel diode detector and said resistor being electrically connected in parallel, a first capacitor connected in parallel with both said resistor and said tunnel diode detector, a second capacitor connected in series with said resistor and in parallel with said tunnel diode detector, and an RF switch controller amplifier; a coupler adapted and connected to electrically connect said RF switch controller to the antenna so that said RF switch controller receives the RF signal from said antenna; and an LNA electrically connected to said RF switches so that said LNA device receives the attenuated RF signal from said RF switches.