Combined multiplexer and switched gain circuit

A multiplexer and switched gain circuit for multiplexing a plurality of analog input signals, said circuit comprising:

• a plurality of input lines responsive to the analog signals;
• an output line;
• a current source providing a source of current, and
• a plurality of conduction paths coupling the current source and the output line, each conduction path including a plurality of switching devices and at least one gain device, wherein an input line is coupled to one of the switching devices in each conduction path, and wherein a control line is coupled to another switching device in each conduction path, said control line selectively providing a control signal to turn on the switching device in the conduction path to transfer the analog signal on the input line to the output line with a gain provided by the at least one gain device in the conduction path.

A multiplexer and switched gain circuit for multiplexing differential analog signals from a primary channel and a diversity channel in a diversity receiver, both of the primary channel and the diversity channel analog signals including a first part and a second part, said circuit comprising:

• an output line;
• a current source for providing a source of current,
• a first primary channel conduction path coupling the current source and the output line, said first primary channel conduction path including a first bipolar transistor responsive to the first part of the primary channel differential signal at its base terminal, a second bipolar transistor responsive to the second part of the primary channel differential analog signal at its base terminal, a third bipolar transistor and a fourth bipolar transistor both coupled to a first control line at their base terminal, said first primary channel conduction path further including a first degenerative resistor, said first control line providing a control signal to turn on the first primary channel conduction path to transfer the primary channel differential analog signal to the output line with a gain provided by the first degenerative resistor;
• a second primary channel conduction path coupled to the current source and the output line, said second primary channel conduction path including a fifth bipolar transistor responsive to the first part of the primary channel differential signal at its base terminal, a sixth bipolar transistor responsive to the second part of the primary channel differential analog signal at its base terminal, a seventh bipolar transistor and an eighth bipolar transistor both coupled to a second control line at their base terminal, said second primary channel conduction path further including a second degenerative resistor, said second control line providing a control signal to turn on the second primary channel conduction path to transfer the primary channel differential analog signal to the output line with a gain provided by the second degenerative resistor;
• a first diversity channel conduction path coupling the current source and the output line, said first diversity channel conduction path including a ninth bipolar transistor responsive to the first part of the diversity channel differential signal at its base terminal, a tenth bipolar transistor responsive to the second part of the diversity channel differential analog signal at its base terminal, an eleventh bipolar transistor and a twelfth bipolar transistor both coupled to a third control line at their base terminal, said first diversity channel conduction path further including a third degenerative resistor, said third control line providing a control signal to turn on the first diversity channel conduction path to transfer the diversity channel differential analog signal to the output line with a gain provided by the third degenerative resistor;
• and
• a second diversity channel conduction path coupling the current source and the output line, said second diversity channel conduction path including a thirteenth bipolar transistor responsive to the first part of the diversity channel differential signal at its base terminal, a fourteenth bipolar transistor responsive to the second part of the diversity channel differential analog signal at its base terminal, a fifteenth bipolar transistor and a sixteenth bipolar transistor both coupled to a fourth control line at their base terminal, said second diversity channel conduction path further including a fourth degenerative resistor, said fourth control line providing a control signal to turn on the second diversity channel conduction path to transfer the second diversity channel differential analog signal to the output line with a gain provided by the fourth degenerative resistor.

A multiplexer for multiplexing analog signals, said multiplexer comprising:

• an output line;
• a first signal path responsive to a first analog signal, said first signal path including a first amplifier for amplifying the first analog signal, said first signal path being coupled to the output line;
• a second signal path responsive to the first analog signal, said second signal path being coupled to the output line;
• a third signal path responsive to a second analog signal, said third signal path including a second amplifier for amplifying the second analog signal, said third signal path being coupled to the output line;
• and
• a fourth signal path responsive to the second analog signal, said fourth signal path being coupled to the output line, wherein the multiplexer selectively outputs the first or second analog signal to the output line through the first, second, third or fourth signal path.

A multiplexer for multiplexing analog signals, said multiplexer comprising:

• an output line;
• a first signal path responsive to a first analog signal, said first signal path including an amplifier for amplifying the first analog signal, said amplifier including a degenerative resistor, said first signal path being coupled to the output line;
• and
• a second signal path responsive to a second analog signal, said second signal path being coupled to the output line, wherein the multiplexer selectively outputs the first or second analog signal on the output line.