EE 140 ANALOG INTEGRATED CIRCUITS SPRING 2011 C Nguyen PROBLEM SET 4 Issued Tuesday Feb 15 2011 Due Tuesday Feb 22 2011 5 00 p m in the EE 140 homework box in 240 Cory 1 Write the expressions for the gain of each circuit in Fig PS4 1 at very low and very high frequencies Neglect other capacitances and assume 0 for circuits a and b and 0 for all of the circuits The expressions should be in terms of the given elements and parameters of the small signal equivalent circuits i e gm r etc for the transistors used a b c d Fig PS4 1 EE 140 ANALOG INTEGRATED CIRCUITS SPRING 2011 C Nguyen 2 The circuit of Fig PS4 2 produces a supply insensitive current Calculate the ratio of small signal variations in IBIAS to small signal variations in VDD at low frequencies Ignore the body effect but include finite transistor ro in this calculation Fig PS4 2 3 Consider the circuit of Fig PS4 3 assuming W L 1 3 40 0 5 IREF 0 3mA and 0 Use the following parameters for your calculation if necessary Vth0 0 7V 2 F 0 9V LD 0 08 m no 350cm2 Vs 0 1V 1 tox 9nm a Determine Vb such that VX VY b If Vb deviates from the value calculated in part a by 100mV what is the mismatch between Iout and IREF c If the circuit fed by the cascode current source changes VP by 1V how much does VY change Fig PS4 3 EE 140 ANALOG INTEGRATED CIRCUITS SPRING 2011 C Nguyen 4 A BICMOS amplifier is shown in Fig PS4 4 Calculate the small signal voltage gain vo vi Assume IS 10 16 A F 100 rb 0 VA nCox 200uA V Vt 0 6V and 0 Fig PS4 4
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