Transconductor stage with controlled gain

A controlled gain transconductor comprising:

• a transconductance stage having at least two input terminals and at least two output terminals;
• an active load connected to the output terminals of said stage;
• and
• a control circuit for the active load connected between said output terminals and the active load, said control circuit comprising a common-mode signal feedback circuit connected to said output terminals of said transconductance stage, a DC-gain adjustment circuit having an output connected to said feedback circuit, and a current-mirror circuit portion connected between said adjustment circuit and said active load.

A controlled gain transconductor comprising:

• a transconductance stage having at least two input terminals and at least two output terminals;
• an active load connected to the output terminals of said stage;
• and
• a control circuit for the active load connected between said output terminals and the active load;
• a circuit portion being a replica of said transconductance stage, said active load and said control circuit, which circuit portion has an output connected to the control circuit of the transconductor.

A method for controlling the gain of a transconductance stage comprising the steps of:

• accepting a voltage input and deriving a corresponding current output in a transconductance stage;
• loading said output with an active load;
• providing a constant voltage sufficient to control the DC gain of the transconductance stage;
• and
• varying the output resistance of said active load according to said constant voltage and feedback from said output to achieve the desired gain.

A controlled-gain transconductor comprising:

• an input stage;
• a load stage connected to supply a bias current to said input stage;
• a compensating stage connected to said load stage to control the bias of said load stage;
• and
• a dummy stage connected to said compensating stage to supply an appropriate constant voltage;
• wherein said dummy stage comprises a replica of said input stage, said load stage and said compensating stage, said dummy stage having an output connected to said compensating stage of said transconductor.

A controlled-gain integrator comprising:

• a transconductance stage having at least two input terminals and at least two output terminals;
• an active load connected to the output terminals of said transconductance stage;
• a control circuit for said active load connected between said output terminals and said active load, said control circuit comprising a common-mode signal feedback circuit connected to said output terminals of said transconductance stage, a DC-gain adjustment circuit having an output connected to said feedback circuit, and a current-mirror circuit portion connected between said adjustment circuit and said active load;
• and
• an integration circuit connected to said transconductance stage.

A controlled gain integrator, comprising:

• a transconductance stage having at least two input terminals and two output terminals;
• and
• a variable load connected to supply a bias current to said output terminals of said transconductance stage;
• a feedback circuit also connected to said output terminals of said conductor stage;
• an adjustment circuit connected to both said feedback circuit and said load circuit to control the bias of said load circuit, said adjustment circuit comprising at least one transistor pair having at least one terminal in common and connected to said feedback circuit;
• and
• an integration circuit connected to said transconductance stage.

A controlled-gain integrator comprising:

• a transconductance stage having at least two input terminals and at least two output terminals;
• an active load connected to the output terminals of said transconductance stage;
• a control circuit for said active load connected between said output terminals and said active load;
• a circuit portion being a replica of said transconductance stage, said active load and said control circuit, which circuit portion has an output connected to the control circuit of the transconductor;
• and
• an integration circuit connect to said transconductance stage.