L12_L11Part1 6.4.3 Open-CircuitTime Constants_1

# L12_L11Part1 6.4.3 Open-CircuitTime Constants_1 - 6.4...

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6.4 Zubair Rehman Theory for Method of Open- Circuit Time Constants Note: Material for this section was derived from  "Electronic Principles: Physics, Models, and Circuits" by  Paul E. Gray and Campbell L. Searle, Ch 15.2, pp. 531- 535, Wiley, 1969.

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2 The Method of Open-Circuit Time Constants Approximate Transfer Function at High Frequencies Any multistage amplifier will have many high frequency poles and zeroes. V o (s) / V i (s) = (K) * [(s - s 1 ) (s - s 3 ) … ] / [(s - s 2 ) (s - s 4 ) … (s - s 2n )] V o (s) / V i (s) = (K) * [(- s 1 ) (- s 3 ) … ] / [(s - s 2 ) (s - s 4 ) … (s - s 2n )] if all the zeroes are large in magnitude as often is the case. V o (s) / V i (s) = K’ / (s n + a n-1 s n-1 + … a 1 s + a 0 ) V o (s) / V i (s) | midband = K’ / a 0 all frequency dependent terms are small. s = j ω ω = small As the frequency is increased from the midband, the term a 1 s = a 1 (jw) becomes important. The other terms in s are assumed small. V
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L12_L11Part1 6.4.3 Open-CircuitTime Constants_1 - 6.4...

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