Fast Compensation Extends Power

　　In all IC operational amplifiers the power bandwidth depends on the frequency compensation. Normally， compensation for unity gain operation is accompanied by the lowest power bandwidth. A technique is presented which extends the power bandwidth of the LM101A for non-inverting gains of unity to ten， and also reduces the gain error at moderate frequencies. In order to achieve unconditional stability， an operational amplifier is rolled off at 6 dB per octave， with an accompanying 90 degrees of phase shift， until a gain of unity is reached. Unity gain in most monolithic operational amplifiers is limited to 1 MHz， because the lateral PNP’s used for level shifting have poor frequency response and exhibit excess phase shift at frequencies above 1 MHz. Hence， for stable operation， the closed loop bandwidth must be less than 1 MHz where the phase shift remains below 180 degrees.