Design of a buck regulator to meet closed-loop output impedance specifications. The buck converter with control system illustrated in Fig. 4 is to be designed to meet the following specifications. The closed-loop output impedance should be less than 0.2 Ω over the entire frequency range from 0 to 20 kHz . To ensure that the transient response is well-behaved, the poles of the closed-loop transfer functions, in the vicinity of the crossover frequency, should have Q-factors no greater than unity.

Power fundamentals of buck regulator architectures | TI.com

Buck Converter Circuit Using Arduino – Homemade Circuit Projects