Bipolar OTA using multitail cell

A bipolar operational transconductance amplifier comprising:

• first to n-th differential pairs of first to 2n-th bipolar transistors whose emitters are coupled together, where n is an integer equal to or greater than two;
• a (2n+1)-th bipolar transistor whose emitter is coupled together to be connected to said coupled emitters of first to 2n-th transistors;
• a common current source or sink connected to said emitters of said first to 2n-th transistors of said first to n-th differential pairs and said (2n+1)-th transistor;
• said first to 2n-th transistors of said first to n-th differential pairs and said (2n+1)-th transistor being driven by a common tail current produced by said common current source or sink;
• said transistors of each of said second to n-th differential pairs having a same emitter area K.sub.1 to K.sub.n-1 times as large as that of said first and second transistors of said first differential pair, where K.sub.1 to K.sub.n-1 are constants greater than unity;
• said (2n+1)-th transistor having an emitter area K.sub.n times as large as that of said first and second transistors of said first differential pair, where K.sub.n is a constant greater than unity;
• wherein a first input voltage as an input signal to be amplified is differentially applied across bases of the first and second transistors of the first differential pair;
• and wherein second to n-th input voltages are differentially applied across corresponding bases of said third to 2n-th transistors of said second to n-th differential pairs, respectively;
• and wherein an (n+1)-th input voltage is applied to a base of said (2n+1)-th transistor;
• and wherein each of said second to n-th input voltages is produced by attenuating said first input voltage;
• and wherein first to (n-1)-th pairs of dc offset voltages are applied to said bases of said third to 2n-th transistors of said second to n-th differential pairs, respectively;
• and wherein an amplified output signal is differentially derived from collectors of said first and second transistors of said first differential pair.

A bipolar operational transconductance amplifier comprising:

• a first differential pair of first and second bipolar transistors whose emitters are coupled together;
• a third bipolar transistor whose emitter is connected to said emitters of said first and second transistors;
• a common current source or sink connected to said emitters of said first, second and third transistors;
• said first, second and third transistors being driven by a common tail current produced by said common current source or sink, thereby constituting a triple-tail cell;
• said first and second transistors having a same emitter area;
• and
• said third transistor having an emitter area K times as large as that of said first and second transistors, where K is a constant greater than unity;
• wherein an input voltage as an input signal to be amplified is differentially applied solely across bases of said first and second transistors;
• and wherein a dc voltage is applied to a base of said third transistor;
• and wherein an amplified output signal is differentially derived directly from collectors of said first and second transistors.

A bipolar operational transconductance amplifier comprising:

• a first differential pair of first and second bipolar transistors whose emitters are coupled together;
• a second differential pair of third and fourth bipolar transistors whose emitters are coupled together;
• a common current source or sink connected to said emitters of said first and second transistors and said emitters of said third and fourth transistors;
• said first, second, third and fourth transistors being driven by a common tail current produced by said common current source or sink, thereby constituting a quadritail cell;
• and
• said third and fourth transistors of said second differential pair having a same emitter area K times as large as that of said first and second transistors of said first differential pair, where K is a constant greater than unity;
• wherein a first input voltage as an input signal to be amplified is differentially applied across bases of said first and second transistors;
• and wherein a second input voltage is differentially applied across bases of said third and fourth transistors, and said second input voltage is produced by attenuating said first input voltage;
• and wherein first and second dc offset voltages are applied to bases of said third and fourth transistors, respectively;
• and wherein an amplified output signal is differentially derived from collectors of said first and second transistors.

A bipolar operational transconductance amplifier comprising:

• a first differential pair of first and second bipolar transistors whose emitters are coupled together;
• a second differential pair of third and fourth bipolar transistors whose emitters are coupled together;
• a fifth unpaired bipolar transistor whose emitter is connected to said emitters of said first and second transistors;
• a common current source or sink connected to said emitters of said first, second, third, fourth and fifth transistors;
• said first, second, third, fourth and fifth transistors being driven by a common tail current produced by said common current source or sink, thereby constituting a quit-tail cell;
• said third and fourth transistors of said second differential pair having a same emitter area K1 times as large as that of said first and second transistors of said first differential pair, where K.sub.1 is a constant greater than unity;
• and
• said fifth transistor having an emitter area K2 times as large as that of said first and second transistors of said first differential pair, where K.sub.2 is a constant greater than unity;
• wherein a first input voltage as an input signal to be amplified is differentially applied across bases of said first and second transistors;
• and wherein a second input voltage is differentially applied across bases of said third and fourth transistors, said second input voltage being produced by attenuating said first input voltage;
• a third input voltage is applied to a base of said fifth transistor;
• wherein an amplified output signal is differentially derived from collectors of said first and second bipolar transistors.

A bipolar operational transconductance amplifier comprising:

• a first differential pair of first and second bipolar transistors whose emitters are coupled together;
• a second differential pair of third and fourth bipolar transistors whose emitters are coupled together;
• a third differential pair of fifth and sixth bipolar transistors whose emitters are coupled together;
• a common current source or sink connected to said emitters of said first, second, third, fourth, fifth, and sixth transistors;
• said first, second, third, fourth, fifth, and sixth transistors begin driven by a common tail current produced by said common current source or sink, thereby constituting a hexatail cell;
• said third and fourth transistors of said second differential pair having a same emitter area K.sub.1 times as large as that of said first and second transistors of said first differential pair, where K.sub.1 is a constant greater than unity;
• and
• said fifth and sixth transistors of said third differential pair having an emitter area K.sub.2 times as large as that of said first and second transistors of said first differential pair, where K.sub.2 is a constant greater than unity;
• wherein a first input voltage as an input signal to be amplified is differentially applied across bases of said first and second transistors
• and wherein a second input voltage is differentially applied across bases of said third and fourth transistors, said second input voltage produced by attenuating said first input voltage;
• a third input voltage is applied solely to a base of said fifth transistor;
• wherein an amplified output signal is differentially derived directly from collectors of said first and second bipolar transistors.

A bipolar operational transconductance amplifier comprising:

• a first differential pair of first and second bipolar transistors whose emitters are coupled together;
• a second differential pair of third and fourth bipolar transistors whose emitters are coupled together;
• a third differential pair of fifth and sixth bipolar transistors whose emitters are coupled together;
• a seventh unpaired bipolar transistor whose emitter is connected to said emitters of said first and second transistors;
• a common current source or sink connected to said emitters of said first, second, third, fourth and fifth transistors;
• said first, second, third, fourth, fifth, sixth, and seventh transistors being driven by a common tail current produced by said common current source or sink, thereby constituting a septtail cell;
• said third and fourth transistors of said second differential pair having a same emitter area K.sub.1 times as large as that of said first and second transistors of said first differential pair, where K.sub.1 is a constant greater than unity;
• and
• said fifth transistor having an emitter area K.sub.2 times as large as that of said first and second transistors of said first differential pair, where K.sub.2 is a constant greater than unity;
• said sixth transistor having an emitter area K.sub.3 times as large as that of said first and second transistors of said first differential pair, where K.sub.3 is a constant greater than unity;
• wherein a first input voltage as an input signal to be amplified is differentially applied across bases of said first and second transistors;
• and wherein a second input voltage is differentially applied across bases of said third and fourth transistors, said second input voltage being produced by attenuating said first input voltage;
• and wherein a third input voltage is differentially applied across bases of said fifth and sixth transistors, said third input voltage being produced by attenuating said first input voltage;
• a fourth input voltage is applied to a base of said seventh transistor;
• wherein an amplified output signal is differentially derived from collectors of said first and second bipolar transistors.