Exponential transconductance amplifier

A non-linear transconductance amplifier, comprising:

• a differential input stage, the differential input stage including first and second inputs forming a non-inverting input and an inverting input, respectively, of the amplifier for receiving an input differential signal;
• and
• a non-linear transconductance stage operatively coupled to the differential input stage, the non-linear transconductance stage generating an output of the amplifier having a linear transconductance when the input differential signal is within a predetermined range and a non-linear transconductance when the input differential signal is outside the predetermined range, the non-linear transconductance stage including a threshold circuit for operatively controlling a threshold region of the amplifier wherein the output of the amplifier exhibits a linear transconductance;
• wherein the non-linear transconductance stage comprises:
• first and second load transistors, the load transistors being operatively connected to the differential input stage in a cross-coupled arrangement and the threshold circuit being operatively coupled between the load transistors;
• first and second non-linear transconductance transistors operatively coupled to the first and second load transistors, respectively, the first and second non-linear transconductance transistors forming first and second outputs, respectively, of the amplifier;
• and
• a bias circuit operatively connected to the non-linear transconductance transistors for biasing the non-linear transconductance stage to a predetermined quiescent operating point.

An integrated circuit including at least one amplifier, the at least one amplifier comprising:

• a differential input stage, the differential input stage including first and second inputs forming a non-inverting input and an inverting input, respectively, of the amplifier for receiving an input differential signal;
• and
• a non-linear transconductance stage operatively coupled to the differential input stage, the non-linear transconductance stage generating an output of the amplifier having a linear transconductance that is substantially zero when the input differential signal is within a predetermined range and a non-linear transconductance when the input differential signal is outside the predetermined range, the non-linear transconductance stage including a threshold circuit for operatively controlling a threshold region of the amplifier wherein the output of the amplifier exhibits a linear transconductance;
• wherein the non-linear transconductance stage comprises first and second load transistors, the threshold circuit being operatively coupled between the load transistors.

An integrated circuit including at least one amplifier, the at least one amplifier comprising:

• a differential input stage, the differential input stage including first and second inputs forming a non-inverting input and an inverting input, respectively, of the amplifier for receiving an input differential signal;
• and
• a non-linear transconductance stage operatively coupled to the differential input stage, the non-linear transconductance stage generating an output of the amplifier having a linear transconductance that is substantially zero when the input differential signal is within a predetermined range and a non-linear transconductance when the input differential signal is outside the predetermined range, the non-linear transconductance stage including a threshold circuit for operatively controlling a threshold region of the amplifier wherein the output of the amplifier exhibits a linear transconductance;
• wherein the non-linear transconductance stage in each of the amplifiers comprises:
• first and second load transistors, the load transistors being operatively connected to the differential input stage in across-coupled arrangement and the threshold circuit being operatively coupled between the load transistors;
• first and second non-linear transconductance transistors operatively coupled to the first and second load transistors, respectively, the first and second non-linear transconductance transistors forming first and second outputs, respectively, of the amplifier;
• and
• a bias circuit operatively connected to the non-linear transconductance transistors for biasing the non-linear transconductance stage to a predetermined quiescent operating point.

A non-linear transconductance amplifier, comprising:

• a differential input stage, the differential input stage including first and second inputs forming a non-inverting input and an inverting input, respectively, of the amplifier for receiving an input differential signal;
• and
• a non-linear transconductance stage operatively coupled to the differential input stage, the non-linear transconductance stage generating an output of the amplifier having a linear transconductance when the input differential signal is within a predetermined range and a non-linear transconductance when the input differential signal is outside the predetermined range, wherein said non-linear transconductance stage may be adjusted to control a threshold region wherein the output of the amplifier exhibits a linear transconductance;
• wherein the non-linear transconductance stage includes a threshold circuit having a single resistance element and the threshold region of the amplifier is selected by operatively adjusting a value of the resistance element.