Current mirror amplifiers with programmable current gains

A programmable-gain current mirror amplifier comprising:

• input, output and common terminals;
• first and further master mirroring transistors and a slave mirroring transistor, each transistor having first and second electrodes with a principal conduction path therebetween and having a control electrode, the conductance of the principal conduction path of each transistor being controlled according to control potential between its second and control electrodes;
• means connecting the first electrodes of said master mirroring transistors to said input terminal;
• means connecting the first electrode of said slave mirroring transistor to said output terminal;
• a direct-coupled feedback connection from the first electrode of said first master transistor to its control electrode;
• a connection between the control electrodes of said first transistor and said slave mirroring transistor;
• means connecting each of the second electrodes of said master and slave mirroring transistors to said common terminal;
• and
• switching means each associated with a respective further master mirroring transistor for selectively connecting together the control electrodes of said first and said respective further master mirroring transistors.

A programmable-gain current mirror amplifier apparatus comprising:

• a bus for application of a reference potential;
• an input terminal for application of a reference current;
• a control terminal for application of a digital control potential;
• and
• first and second and third field effect transistors of a first conductivity type and a fourth field effect transistor of a second conductivity type complementary to said first conductivity type, each of said transistors having gate and source and drain electrodes, the source electrodes of said first and said second and said third transistors being connected to said bus, said first transistor gate and drain electrodes and said fourth transistor source electrode being connected to said input terminal, the gate electrodes of said third and fourth transistors being connected to said control terminal and their drain electrodes being connected to said second transistor gate electrode, said second transistor drain electrode being available for further connection.

A programmable-gain current mirror amplifier apparatus comprising:

• a bus for application of a reference potential;
• an input terminal for application of a reference current;
• an output terminal for connection to supply an output current;
• control means for providing a bit-parallel binary control signal manifestation;
• first and second transistor means, each having an input connection and a common connection and an output connection, at least one of said first and said second transistor means having a transconductance selectably determinable between a plurality of values responsive to a portion of said control signal manifestation;
• means coupling the common connection of each of said first and said second transistor means to said bus;
• means coupling the output connection of said first transistor means to said input terminal;
• means coupling the output connection of said second transistor means to said output terminal;
• and
• a pair of similar means respectively for coupling the input connection of said first transistor means to said input terminal and for coupling the input connection of said second transistor means to said input terminal.