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Unformatted text preview: ECE 315 Homework 1 Solution Spring 2009 1. (Simple definition of signals) Briefly (in 1 to 3 sentences) explain the following: (a) Describe the Moores law in terms of transistor counts, smallest feature and cost per bit. (4 pts) From Fig. 1.1, we can roughly estimate: Transistor count: double every 18 month. Smallest feature: half every 5 years. Cost per bit: half every 18 months. (b) What is the basic difference in transient values between digital and analog representation when v(t) or i(t) is used in microelectronics? (4 pts) Analog signals are represented by the floating point value of v(t) or i(t) , while digital signals by the digitized (with a threshold voltage or the binary voltage values given) value. (c) What is the difference in the ambient noise effect between digital and analog signals? (4 pts) The noise in analog signals will accumulate, while the polluted digital signal can be regenerated. (d) A transistor on a 65nm CMOS technology usually drives a capacitance of 100fF. Assume we have a hundred million transistors with V DD = 1V and the system clock is 1GHz. What is the dynamic power consumption? What is the factor that we did not consider here? (4 pts) CV 2 f = 10-13 10 8 1 2 10 9 = 10 4 (W). We did not consider that not all the transistors are switching at the same time. The transistors that are directly on the clock path will switch for every clock cycle though. (e) For the realistic voltage transfer curve of Fig. 1.13, describe how voltage gain affects the input signal range without output saturation. (4 pts) When the gain is higher, since the output voltage is bounded by...
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