Small-Signal Models of PWM Converters for CCM and DCM

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Yu-Jun Mao ◽  
Chi-Seng Lam ◽  
Sai-Weng Sin ◽  
Man-Chung Wong ◽  
Rui Paulo Martins

Among various modeling methods for DC-DC converters introduced in the past two decades, the state-space averaging (SSA) and the circuit averaging (CA) are the most general and popular exhibiting high accuracy. However, their deduction approaches are not entirely equivalent since they incorporate different averaging processes, thus yielding different small signal transfer functions even under identical operating conditions. Some research studies claimed that the improved SSA can obtain the highest accuracy among all the modeling methods, but this paper discovers and clearly verifies that this is not the case. In this paper, we first review and study these two modeling methods for various DC-DC converters operating in the discontinuous conduction mode (DCM). We also streamline the general model-deriving processes for DC-DC converters, and test and compare the accuracy of these two methods under various conditions. Finally, we provide a selection strategy for a high-accuracy modeling method for different DC-DC converters operating in DCM and verified by simulations, which revealed necessary and beneficial for designing a more accurate DCM closed-loop controller for DC-DC converters, thus achieving better stability and transient response.


Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 266
Author(s):  
Ruirui Dang ◽  
Lijie Yang ◽  
Zhihao Lv ◽  
Chunyi Song ◽  
Zhiwei Xu

Accurate large signal GaAs pHEMT models are essential for devices’ performance analysis and microwave circuit design. This, in turn, mandates precise small signal models. However, the accuracy of small signal models strongly depends on reliable parasitic parameter extraction of GaAs pHEMT, which also greatly influences the extraction of intrinsic elements. Specifically, the parasitic source and drain resistances, R s and R d , are gate bias-dependent, due to the two-dimensional charge variations. In this paper, we propose a new method to extract R s and R d directly from S-parameter measurements of the device under test (DUT), which save excessive measurements and complicated parameter extraction. We have validated the proposed method in both simulation and on-wafer measurement, which achieves better accuracy than the existing state-of-the-art in a frequency range of 0.5–40 GHz. Furthermore, we develop a GaAs pHEMT power amplifier (PA) to further validate the developed model. The measurement results of the PA at 9–15 GHz agree with the simulation results using the proposed model.


Sign in / Sign up

Export Citation Format

Share Document