Final answer:
Propagation delay in a CMOS ring oscillator can be calculated by determining the delay through a single inverter and multiplying by the total number of inverters. This delay affects the oscillation frequency of the ring oscillator. Accurate measurement requires consideration of various factors or the use of simulation tools.
Step-by-step explanation:
To calculate the propagation delay in a CMOS ring oscillator, you need to understand the oscillator's structure and operation. A CMOS ring oscillator consists of an odd number of not gates, or inverters, connected in a series such that the output of the last inverter is fed back to the input of the first. This creates a feedback loop that allows the signal to oscillate. The total propagation delay of the oscillating signal is the cumulative delay as it passes through each inverter in the loop.
The propagation delay of a single inverter can be determined using the following formula: Td = (C_load * V_DD) / I_DD, where Td is the delay, C_load is the load capacitance, V_DD is the supply voltage, and I_DD is the current supplied by the inverter. In a ring oscillator, the total delay is the product of the single inverter delay and the number of inverters. The oscillation frequency of the ring oscillator is then given by F = 1 / (2 * N * Td), where F is the frequency and N is the number of inverters.
It's important to consider that factors such as temperature, supply voltage variations, and manufacturing differences can affect the propagation delay. To accurately measure the delay, you can use experimental methods such as applying a known signal and measuring the output or leveraging sophisticated electronic design automation (EDA) tools that simulate the ring oscillator's behavior.