Radio communication apparatus with expanded dynamic range

A radio communication apparatus comprising:

• a first signal path for amplifying and detecting a received signal and transferring said received signal to a demodulator;
• a second signal path for amplifying and detecting said received signal separately from said first signal path;
• and
• a signal strength detector circuit for detecting the field strength of said received signal from a detection signal extracted from said first signal path and a detection signal extracted from said second signal path,
• wherein said first signal path includes a first differential pair of transistors having emitters and collectors, respectively;
• collector resistors connected to the collectors of said first differential pair of transistors;
• and a current source directly connected to said emitters;
• and a second differential pair of transistors having collectors and emitters, respectively;
• collector resistors connected to the collectors of said second differential pair of transistors;
• emitter resistors connected to the emitters of said second differential pair of transistors;
• and a current source connected to said emitter resistors;
• and
• wherein said second signal path includes a third differential pair of transistors having collectors and emitters, respectively;
• collector resistors connected to the collectors of said third differential pair of transistors;
• emitter resistors connected to the emitters of said respective transistors;
• and a current source connected to the emitter resistors.

A radio communication apparatus comprising:

• a radio receiver section;
• a radio transmitter section;
• a signal strength detector circuit for determining the field strength of a received signal;
• control means for variably controlling a radio transmitted output in said radio transmitter section based on an output of said signal strength detector circuit;
• a first signal path included in said radio receiver section and having a plurality of amplifiers for amplifying, detecting, and transferring a radio received signal from an antenna, said first signal path including a first differential pair of transistors having respective emitters and collectors, and a current source directly connected to said emitters;
• and a second differential pair of transistors having respective collectors and emitters, emitter resistors connected to the emitters of said second differential pair of transistors, and a current source connected to said emitter resistors;
• a demodulator connected to said first signal path for demodulating the signal transferred from said first signal path;
• and
• a second signal path included in said radio receiver section and having at least one amplifier for amplifying, detecting, and transferring said radio received signal separately from said first signal path, said second signal path including a third differential pair of transistors having respective collectors and emitters, emitter resistors connected to the emitters of said third differential pair of transistors, and a current source connected to said emitter resistors;
• wherein said signal strength detector circuit outputs a signal indicative of the field strength of said radio received signal from a detection signal extracted from said first signal path and a detection output extracted from said second signal path;
• and
• wherein said control means variably controls said radio transmitted output based on the output of said signal strength detector circuit.