One of the question asks to find the frequency at which the gain becomes 0dB for a low pass Single Time Constant circuit. In the solution manual after finding the 3dB frequency = 10^6, it states that since the gain falls off at a rate of -20dB/dec (see attatchment for graph) starting at w0(Omega-knot) , which is 10^6, the gain will reach 0dB in 2 decades (a factor of 100), therefore unity gain frequency = (10^6)(10^2)= 10^8. Now i dont understand how the gain will reach 0dB in 2 decades, because if you look at the graph of a low pass stc circuit it starts off at 0dB then falls by -20dB/dec. Am i reading the log scale graphs incorrectly? Please clarify. Thank You.