Random Pattern Generator Using Ring Oscillators
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
This circuit generates digital random patterns and consists of two ring oscillators powered by noisy power supplies. Each power supply is disturbed by the functioning of the ring oscillators. The figure shows two ring oscillators powered by noisy power supplies providing X, Y, Z and T signals and the method of combining those signals in order to deliver a random bit. All the transistors used in the circuit belong to the internal part of a CMOS gate array, i.e., all NMOS transistors N1 to N9, N11 to N15, N21, N22, N23 and N24 have a unique size, and all PMOS transistors P1 to P9, P11 to P15, P21, P22, P23, P24 have a unique size. The first ring oscillator has 9 inverters, each inverter being composed of one NMOS transistor (N1 for the first inverter) and PMOS transistor (P1 for the first inverter).