Common-source amplifier Assume the ideal common-source amplifier shown in Figure 09. To design a single-stage amplifier with a gain-bandwidth product GBW = 25MHz and a load capacitance CL = 1pF, we have gm = 157uA/V. Fig. 09. Common-source amplifier. Using as specifications gm = 157uA/V, fTmin = 100MHz, fTmax = 1000MHz and AVO = 100 and considering as technological parameters Lmin = 1um, C'ox = 2fF/um2, n = 1.25, m0 = 500cm2/Vs, VE = 5V/um and ft = 25.9mV, the design space obtained is shown in Figure 10. Fig. 10. Design space for a common-source amplifier. For Figure 10, some points in the design space were selected. Table I shows the characteristics of the transistors represented for each point. Tab. I. Characteristics of a common-source amplifier GBW = 25MHz, CL = 1pF. It can be observed that point 3 doesn't meet the gain spec, while point 5 doesn't meet neither the gain spec nor the frequency spec. The maximum intrinsic gain of the transistor is for the transistor with the lowest transition frequency fT. On the other hand, the minimum area is associated with the maximum cutoff frequency. Finally, the minimum current consumption transistor is achieved with the lowest inversion level. Amplifier I - Amplifier II - Current Mirror - Tranconductor - CS Amplifier