Input signal level control device for receiver

An input signal level control device for a receiver comprising:

• a first capacitor having a first terminal coupled to an antenna terminal;
• a first coil having a first terminal coupled to a second terminal of said first capacitor and a second terminal coupled to ground;
• a switching diode having a cathode terminal coupled to said first terminal of said first coil;
• a second capacitor having a first terminal coupled to and an anode terminal of said first diode and a second terminal coupled to ground;
• an antenna tuning circuit having an input terminal coupled to said first terminal of said coil;
• a dual-gate first-effect transistor, one of a source and drain electrodes of said field-effect transistor being coupled to ground;
• a third capacitor having a first terminal coupled to an output of said antenna tuning circuit and a second terminal coupled to a first gate of said field-effect transistor;
• a first resistor having a first terminal coupled to said first gate of said field-effect transistor and a second terminal coupled to ground;
• a second coil having a first terminal coupled to the other of said source and drain electrodes of said field-effect transistor;
• a second resistor having a first terminal coupled to said first gate of said field-effect transistor and a second terminal coupled to a second terminal of said second coil;
• a third capacitor having a first terminal coupled to said second terminal of said second coil and the second terminal coupled to ground;
• a first filter having an input coupled to said first terminal of said second coil;
• a frequency converter circuit having an input coupled to an output of said first filter;
• an inter-stage transformer having an input coupled to an output of said frequency converter;
• a second filter having an input coupled to an output of said inter-stage transformer;
• a first amplifier having an input coupled to an output of said second filter;
• a second amplifier having an input coupled to an output of said first amplifier;
• a fourth capacitor having a first terminal coupled to an output of said second amplifier;
• second and third diodes, an anode of said second diode being coupled to a cathode of said third diode and to a second terminal of said fourth capacitor;
• a third resistor having a first terminal coupled to an anode of said third diode and a second terminal coupled to a cathode of said second diode and to said second terminal of said second coil;
• a fifth capacitor coupled in parallel with said third resistor;
• a PNP transistor having a base coupled to said first terminal of said third resistor, an emitter coupled to said second terminal of said third resistor, and a collector coupled to said anode terminal of said first diode;
• a fourth resistor having a first terminal coupled to said emitter of said PNP transistor and a second terminal coupled to a positive voltage source and to said first terminal of said third capacitor;
• a fifth resistor having a first terminal coupled to said emitter of said PNP transistor;
• a sixth capacitor having a first terminal coupled to a second terminal of said fifth resistor and a second terminal coupled to ground;
• and a sixth resistor having a first terminal coupled to said second terminal of said fifth resistor and a second terminal coupled to a second gate of said field-effect transistor.

An input signal level control device for a receiver receiving an input signal having a particular electric field strength, comprising:

• an input signal source;
• an attenuating means for attenuating a level of said input signal;
• an amplifier means for amplifying said attenuated input signal;
• a signal processing means for processing said amplified signal;
• and a control means receiving said processed signal, said control means activating said attenuating means when said electric field strength of said input signal reaches a first level and controlling said amplifying means when said electric field strength of said input signal reaches a second level greater than said first level, said control means having a first transistor coupled with a second transistor, said attenuating means being activated by an output of said first transistor and said amplifier means being controlled by an output of said second transistor.

An input signal level control device for a receiver receiving an input signal having a particular electric field strength, comprising:

• an input signal source;
• an attenuating means for attenuating a level of said input signal;
• an amplifier means for amplifying said attenuated input signal;
• a signal processing means for processing said amplified signal;
• and a control means receiving said processed signal for both activating said attenuating means when said electric field strength of said input signal reaches a first level and controlling said amplifying means when said electric field strength of said input signal reaches a second level greater than said first level, said control means comprising an input amplifier having an input coupled to an output of an IF amplifier of said processing means, a rectifying and smoothing circuit having an input coupled to an output of said input amplifier, a first amplifying transistor having a base input coupled to an output of said rectifying and smoothing circuit, a second amplifying transistor having a base input coupled to a collector output of said first transistor, said collector output of said first transistor being connected to said attenuating means, and a collector output of said second amplifying transistor being coupled to a gain control input of said amplifier means.