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university:courses:electronics:text:chapter-3 [16 Nov 2016 19:47] – correctin text back to original as a result of correcting error in figure labels G1 G2 Doug Mercer | university:courses:electronics:text:chapter-3 [06 Jun 2017 16:49] (current) – [3.2.3 Loop gain] Doug Mercer | ||
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This loop gain discussion emphasizes that indeed, loop gain is a very significant factor in predicting the performance of closed-loop operational amplifier circuits. The open-loop gain required to obtain an adequate amount of loop gain will, of course, depend on the desired closed-loop gain. | This loop gain discussion emphasizes that indeed, loop gain is a very significant factor in predicting the performance of closed-loop operational amplifier circuits. The open-loop gain required to obtain an adequate amount of loop gain will, of course, depend on the desired closed-loop gain. | ||
- | For example, using equation 3-9, an amplifier with A< | + | For example, using equation 3-9, an amplifier with A< |
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+ | **ADALM1000 Lab Activity [[university: | ||
====3.2.4 Frequency Dependence of Loop Gain ==== | ====3.2.4 Frequency Dependence of Loop Gain ==== | ||
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Figure 3.2 illustrates that the high open-loop gain figures typically quoted for op amps can be somewhat misleading. As noted, beyond a few Hz, the open-loop gain falls at 6dB/octave. Consequently, | Figure 3.2 illustrates that the high open-loop gain figures typically quoted for op amps can be somewhat misleading. As noted, beyond a few Hz, the open-loop gain falls at 6dB/octave. Consequently, | ||
- | A direct approach to improving loop gain at high frequencies other than by increasing open-loop gain is to increase the amplifier open-loop bandwidth. figure 3.2 shows this in terms of two simple examples. It should be borne in mind however that op amp gain-bandwidths available today extend to the hundreds of MHz, allowing video and high-speed communications circuits to fully exploit the virtues of feedback. | + | A direct approach to improving loop gain at high frequencies other than by increasing open-loop gain is to increase the amplifier open-loop bandwidth. figure 3.2 shows this in terms of two simple examples. It should be borne in mind however that op amp gain-bandwidths available today extend to the hundreds of MHz, allowing video and high-speed communications circuits to fully exploit the virtues of feedback. |
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+ | **ADALM1000 Lab Activity [[university: | ||
====3.2.5 The Bode Plot: Asymptotic And Actual Responses==== | ====3.2.5 The Bode Plot: Asymptotic And Actual Responses==== |