ECE 315 Homework 9 Due 11:15am, November 19, 2007 in the drop box 1.(Design of cascode differential amplifier)(a)Sketch the circuit diagram of an active-load MOS differential amplifier where the input transistors are cascoded, and a cascode current mirror is used for the active load. (8 pts) (b)If all of your NMOS transistors are operated at an overdrive voltage of VOVand all NMOS and PMOS transistors have the same early voltage of |VA|, derive the gain expression as: Ad= 2(VA/VOV)2. Evaluate the gain for VOV=0.25V and VA=20V. (8 pts) 2.(Frequency response of amplifiers) For an NMOSFET in an amplifier setup with Cgs=0.5pF, Cgd=0.1pF, Cdb=0.1pF, CL=1pF (including Cdb), gm=5mA/V, ro= 20kΩ, and Rsig= RL= 20kΩ, (a)In the CS amplifier of Fig. 6.20, use the Miller theorem to find the quasi-static gain AMand the 3-dB corner frequency fH. (8 pts) (b)Repeat (a) with the open-circuit time constant method. Is the answer different? Give the percentage contribution to τHby each of the three capacitances (Cgs, Cgdand CL). Give also the gain-bandwidth product. (8 pts)
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