On-Chip Compensation for Operational Amplifiers
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Conventional integrated operational amplifiers use Miller multiplication of an integrated capacitor in the signal path for system stability. The illustrated circuit uses a beta multiplier instead. This technique allows the design and compensation of a fast operational amplifier using only a few components and a small junction capacitor (3 pf). The capacitor multiplier transistor 6 in this circuit is not in the gain path as in conventional Miller amplifiers. The signal path contains only a single voltage gain stage composed of the twin tailed pair 1 and 2, mirrored by diode 3 and transistor '4'. A portion of the signal at 7 passes through the compensation capacitor 8. This current is divided between the base resistor 9 and the base impedance of transistor 6.