ESE 372 / Spring 2013 / Lecture 21 Common Source Amplifier (biased by current source) 1 ESE 372 / Spring 2013 / Lecture 21 Common Source Amplifier with RSS (improves dynamic range) 2 ESE 372 / Spring 2013 / Lecture 21 Common Gate Amplifier (biased by current source) 3 ESE 372 / Spring 2013 / Lecture 21 Common Drain Amplifier (biased by current source) 4 ESE 372 / Spring 2013 / Lecture 21 MOSFET model with capacitances 5 ESE 372 / Spring 2013 / Lecture 21 Unity gain frequency/bandwidth 6 ESE 372 / Spring 2013 / Lecture 21 Frequency response of CS amplifier 7 ESE 372 / Spring 2013 / Lecture 21 Low frequency cutoff fL 8 ESE 372 / Spring 2013 / Lecture 21 High frequency cutoff fH 9 ESE 372 / Spring 2013 / Lecture 21 Miller Transformation Equivalent circuit 10 ESE 372 / Spring 2013 / Lecture 21 Miller Transformation in CS amplifier Equivalent circuit 11 ESE 372 / Spring 2013 / Lecture 21 Another way of looking at it –open circuit time constants. The high frequency 3dB cutoff can be estimated as: Open circuit time constants corresponding to each capacitor in the small signal equivalent circuit: 12 ESE 372 / Spring 2013 / Lecture 21 Another way of looking at it –open circuit time constants. 13 ESE 372 / Spring 2013 / Lecture 21 Common Gate Amplifier Moderate freq. equivalent circuit 14 ESE 372 / Spring 2013 / Lecture 21 Common Gate Amplifier 15 ESE 372 / Spring 2013 / Lecture 21 High frequency cut‐off of CS amplifier with capacitive load 16 ESE 372 / Spring 2013 / Lecture 21 Capacitive load and open circuit time constants LPF at the output due to capacitive load dominates. We need voltage buffer to deal with CL 17 ESE 372 / Spring 2013 / Lecture 21 Common Drain Amplifier with capacitive load Low/Moderate ffqreq. equivalent circuit 18 ESE 372 / Spring 2013 / Lecture 21 Common Drain Amplifier with capacitive load 19 ESE 372 / Spring 2013 / Lecture 21 Basic concept of tuned amplifier 20.