Comparison: Telescopic Op-Amp with Current Mirror and Fully - PowerPoint PPT Presentation

4 Comparison: Telescopic Op-Amp with Current Mirror and Fully Differential Telescopic Op-Amp Circuit I Circuit II Mirror pole in circuit I - No effective mirror pole in circuit II - Effect of poles at nodes N and K (in the cascode active load)? IIT-Bombay Lecture 29 M. Shojaei Baghini

5 Compensation • Compensation of single-stage op amps can be achieved by controlling the location of the dominant pole. • What about two-stage op amps? For example two dominant poles in fully differential two- stage op amp (given in the next side). IIT-Bombay Lecture 29 M. Shojaei Baghini

6 Two-Stage Op-Amp • Providing more gain, compared to single-stage amplifiers (gain can reach to order of (gm × ro ) 3 • Isolating gain and swing stages • More convenient for feedback configurations • First stage has more gain than the second stage. IIT-Bombay Lecture 29 M. Shojaei Baghini

7 Compensation of Two-Stage Op Amp P E P A P X P E P A P X IIT-Bombay Lecture 29 M. Shojaei Baghini

8 Pole Splitting with Miller Compensation IIT-Bombay Lecture 29 M. Shojaei Baghini