6.7 L22 (L13 Part 3) CG &CB with Active_Loads_1

6.7 L22 (L13 Part 3) CG &CB with Active_Loads_1 -...

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Lecture 21 Monday March 2 Lecture 13 Part 3 6.7 The Common-Gate & Common-Base with Active Loads Zubair Rehman
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2 Body Effect (V BS ≠ 0) Body not connected to Source i = g m v gs + g mb v bs g mb = X g m X is in the range 0.1 to 0.2 Figure 6.27 (a) Active-loaded common-gate amplifier. (b) MOSFET equivalent circuit for the CG case in which the body and gate terminals are connected to ground.
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3 Input Resistance with R L = infinity Open-Circuit Input Resistance R in = V test /I test i = (g m + g mb )v gs for v bs = v gs v gs = - v test i = - (g m + g mb )v test i’ = - i = (g m + g mb )v test v ds = i’r o v o = v ds + v test v o = v test + (g m + g mb )r o v test I test = ? I test = 0 There is no path to ground I test Open-Circuit Voltage Gain A vo = v o / v test A vo = 1 + (g m + g mb )r o A vo can be quite large
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4 Connect R L Now there is a path to ground for I test R in = v test / I test I test = i’ + i ro i’ = - i = - (g m + g mb )v gs = (g m + g mb )v test v d = I test R L = (i’ + i
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6.7 L22 (L13 Part 3) CG &CB with Active_Loads_1 -...

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