9.91 Figure P9.91 shows the current-mirror-loaded MOS differential amplifier prepared for small-signal analysis. We have "pulled out" ro of each transistor; thus, the current in the drain of each transistor will be gmvgs. To help the reader, we have already indicated approximate values for some of the node voltages. For instance, the output voltage vo = 1/ 2 / gmro / vid , which we have derived in the text. The voltage at the common sources has been found to be approximately +vid /4, which is very far from the virtual ground one might assume. Also, the voltage at the gate of the mirror is approximately -vid /4, confirming our contention that the voltage there is vastly different from the output voltage, hence the lack of balance in the circuit and the unavailability of a Differential half-circuit. Find the currents labeled i1 to i13 in terms of (gmvid ). Determine their values in the sequence of their numbering and assume gmro Note that all transistors are assumed to be operating at the same /VOV /. Write the current values on the circuit diagram and reflect on the results.
