Linearized level-shifting amplifier

A differential amplifier (100) comprising:

• first and second identical amplifier halves, each amplifier half including
• a load (Il;
• I2);
• a current source (I3;
• I4);
• voltage shifting means (R2, C2;
• R4, C1) having a first node coupled to the load and a second node coupled to the current source;
• a first amplifier (Q1;
• Q2) having a single-ended voltage input coupled to ground and an output coupled to the first node of the voltage shifting means;
• a second amplifier (Q3, Q4;
• Q5, Q6) having a single-ended current output and an input coupled to the second node of the voltage shifting means;
• and
• means (15, 17) for coupling the first and second amplifiers such that a portion of bias and signal currents flowing through the second amplifier flows through the first amplifier;
• and
• an input current (I10) flowing between the first and second identical amplifier halves and the single-ended current output of the second amplifier in each amplifier half forming a differential output.

A differential amplifier (130) comprising:

• first and second identical amplifier halves, each amplifier half including
• a load (I1;
• I2);
• a current source (I3;
• I4);
• voltage shifting means (R2, C2;
• R4, C1) having a first node coupled to the load and a second node coupled to the current source;
• a first amplifier (Q1;
• Q2) having a single-ended voltage input, and an output coupled to the first node of the voltage shifting means;
• a second amplifier (Q3;
• Q5) having an input coupled to the second node of the voltage shifting means, and a single-ended voltage output;
• and
• means (15, 17) for coupling the first and second amplifiers such that a portion of bias and signal currents flowing through the second amplifier flows through the first amplifier;
• and
• means (R1) for coupling together the first and second identical amplifier halves, the single-ended voltage input of the first amplifier in each amplifier half forming a differential input, and the single-ended voltage output of the second amplifier in each amplifier half forming a differential output.

A differential amplifier (20, 30, 40, 50, 60, 70, 80, 90, 110, 120) comprising:

• a main differential amplifier (Q1, Q2, R1) having first and second voltage inputs for receiving a differential input voltage, first and second current outputs, and first and second emitter nodes;
• a differential load (I1, I2) coupled to the first and second current outputs;
• a first output amplifier (Q3, Q4, I4) having a first voltage input coupled to a source of reference voltage, a second voltage input, a first current output, and a second current output coupled to the first emitter node of the main differential amplifier;
• a second output amplifier (Q5, Q6, I6) having a first voltage input coupled to a source of reference voltage, a second voltage input, a first current output, and a second current output coupled to the second emitter node of the main differential amplifier, the first current outputs of the first and second output amplifiers forming a differential current output;
• a first level-shifting network (R2, C2) coupled between the first current output of the main differential amplifier and the second voltage input of the first output amplifier;
• a second level-shifting network (R4, C1) coupled between the second current output of the main differential amplifier and the second voltage input of the second output amplifier;
• a first current source (I3) coupled to the second input of the first output amplifier;
• and
• a second current source (I5) coupled to the second input of the second output amplifier.

A differential amplifier (100) comprising:

• a main differential amplifier (Q1, Q2, R1) having first and second voltage inputs coupled to ground, first and second current outputs, and first and second emitter nodes for receiving a differential input current;
• a differential load (I1, I2) coupled to the first and second current outputs;
• a first output amplifier (Q3, Q4, I4) having a first voltage input coupled to a source of reference voltage, a second voltage input, a first current output, and a second current output coupled to the first emitter node of the main differential amplifier;
• a second output amplifier (Q5, Q6, I6) having a first voltage input coupled to a source of reference voltage, a second voltage input, a first current output, and a second current output coupled to the second emitter node of the main differential amplifier, the first current outputs of the first and second output amplifiers forming a differential current output;
• a first level-shifting network (R2, C2) coupled between the first current output of the main differential amplifier and the second voltage input of the first output amplifier;
• a second level-shifting network (R4, C1) coupled between the second current output of the main differential amplifier and the second voltage input of the second output amplifier;
• a first current source (I3) coupled to the second input of the first output amplifier;
• and
• a second current source (I5) coupled to the second input of the second output amplifier.

A differential amplifier (130) comprising:

• a main differential amplifier (Q1, Q2, R1) having first and second voltage inputs for receiving a differential input voltage, first and second current outputs, and first and second emitter nodes;
• a differential load (I1, I2) coupled to the first and second current outputs;
• a first output amplifier (Q3, Q5, R3, R5) having a first and second voltage inputs, first and second current outputs coupled to the first and second emitter nodes of the main differential amplifier, and first and second emitter nodes forming a differential voltage output;
• a second output amplifier (Q8, Q9, I3, I5) having first and second voltage inputs coupled to a source of reference voltage, first and second current outputs coupled to the first and second voltage inputs of the first output amplifier, and first and second emitter nodes;
• a first level-shifting network (R2, C2) coupled between the first current output of the main differential amplifier and the first voltage input of the first output amplifier;
• a second level-shifting network (R4, C1) coupled between the second current output of the main differential amplifier and the second voltage input of the first output amplifier;
• a first current source (I3) coupled to the first emitter node of the second output amplifier;
• and
• a second current source (I5) coupled to the second emitter node of the second output amplifier.