The circuit of Figure P-la has Rs=20k, R = 5k2, and Q1 is biased (bias components are not shown) at Ic=lmA. At this bias, C, 5pF and C=1pF. The transistor has =250 and V = 0. a) What is the time constant at the base? b) What is the -3dB bandwidth of You? V Voc Figure P-la Q1 c) Suppose that a 680-pF load is added from your to ground. Now what is the -3dB bandwidth of ? d) Suppose that a properly-biased common-base stage (Q2) is added between Q1 and Rc in Figure P-la to form a cascode amplifier configuration. Q2 is an identical transistor to Q1, and the 680-pF load of Part (c) is no longer present. Vout is now at the collector of Q2. Now what is the-3dB bandwidth of ?