1. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill Chapter 14 Single-Transistors Amplifiers Microelectronic Circuit Design Richard C. Jaeger Travis N. Blalock Chap 14 - 1

2. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill Noninverting Amplifiers: Common-Base and Common-Gate Circuits AC equivalent for C-E AmplifierAC equivalent for C-S Amplifier Chap 14 - 2

3. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill C-B and C-G Amplifiers: Terminal Voltage Gain and Input Resistance Polarities of v be and dependent current source g m v be are both reversed, signal source is transformed to its Norton equivalent r o is neglected. For C-S Amplifier, take limit of voltage gain of C-E amplifier as Chap 14 - 3

4. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill C-B and C-G Amplifiers: Overall Voltage Gain Overall voltage gain is For C-S Amplifier, For R I >> R 6, For, This is the upper bound on gain. For, r o can be neglected as gain<<  f Chap 14 - 4

5. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill C-B and C-G Amplifiers: Input Signal Range For small-signal operation, In case of FET, Relative size of g m and R I determine signal-handling limits. …for R I >> R 4. Chap 14 - 5

6. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill C-B and C-G Amplifiers: Voltage Gain Calculations (Example) Problem: Find overall voltage gain. Given data: Q-point values and values for R 1, R 2, R 3, R 7,for both BJT and FET, R I =2 k , R 4 =12 k . Assumptions: Small-signal operating conditions. Analysis: For C-E Amplifier, For C-S Amplifier, Chap 14 - 6

7. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill Desired resistance is that looking into collector with base grounded and resistor R th in emitter. The redrawn equivalent circuit is same as that for C-E amplifier except resistance in base is zero and resistance in emitter is relabeled as R th. And for the FET C-G amp C-B and C-G Amplifiers: Output Resistance Chap 14 - 7

8. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill Noninverting Amplifiers: Current Gain Terminal current gain is the ratio of the current delivered to the load resistor to the current being supplied to the base terminal. Chap 14 - 8

9. Jaeger/Blalock 7/26/07 Microelectronic Circuit Design, 3E McGraw-Hill C-B and C-G Amplifiers: Summary C-B and C-G amplifiers have similar voltage and current gains. Numerical differences occur due to difference in parameter values of BJT and FET at similar operating points. C-B amplifier can achieve high output resistance due to higher amplification factor of BJT. C-B amplifier can more easily reach low levels of input resistance due to higher transconductance of BJT for a given operating current. Input signal range of C-G amplifier is inherently larger than that of C-B amplifier. Chap 14 - 9