Differential amplifier arrangement with current regulating circuit and method for operating a differential amplifier arrangement

A method for operating a differential amplifier arrangement comprising:

• providing a current source, at least one input signal transistor coupled thereto and a load coupled in series therewith,
• measuring output signals in common mode fashion and comparing the measured output signals with a reference signal;
• generating a control signal according to the comparison of the measured output signals and the reference signal;
• using the generated control signal to control a DC current of a regulable current source;
• adjusting the reference signal to obtain a voltage swing of the output signal;
• and
• providing the DC current to the at least one input signal transistor and the load.

A differential amplifier arrangement comprising:

• a DC current source;
• a first portion comprising:
• a first controllable path having a first terminal coupled to the DC current source, a second terminal, and a control terminal that receives a first input signal;
• a first cascode circuit having a first terminal coupled to the second terminal of the first controllable path and a second terminal that provides a first output signal;
• and
• a first regulable current source having an output coupled to the first terminal of the cascode circuit and that is regulated according to a control signal;
• a second portion comprising:
• a second controllable path having a first terminal coupled to the DC current source, a second terminal, and a control terminal that receives a second input signal;
• a second cascode circuit having a first terminal coupled to the second terminal of the second controllable path and a second terminal that provides a second output signal;
• and
• a first regulable current source having an output coupled to the first terminal of the second cascode circuit and that is regulated according to the control signal;
• and
• a control circuit coupled to the second terminal of the first cascode circuit and the second terminal of the second cascode circuit and that generates the control signal according to the first output signal generated at the second terminal of the first cascode circuit and the second output signal generated at the second terminal of the second cascode circuit.