This paper presents two types of modified CPW Wilkinson power dividers at X-band using GaN MMIC technology on a SiC substrate. Lumped element equivalents of the transmission line arms are used and they are capacitively loaded to achieve a reduced circuit size of λ/14 × λ/8. A symmetrical series RLC circuit in the isolation network is used to compensate for the bandwidth degradation after circuit miniaturization maintaining a fractional bandwidth of 29% for input/output return losses and isolation better than 20 dB with an extra insertion loss less than 0.35 dB.

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Resistive terminations cannot preserve high-quality matching at high frequencies due to the parasitic effects of the nonideal resistor. Moreover, resistance values of the termination resistors in integrated circuits are subject to process variations. Therefore, it is difficult to obtain accurate and process-tolerant terminations that are crucial for high performance in microwave circuits. We propose a new resistive network that compensates for the high-frequency parasitic effects of the resistors to improve the bandwidth of the termination. In addition to maintaining accuracy, the presented network provides tolerance to variation in the resistor values. The accuracy and tolerance of the proposed structure is analytically shown and experimentally verified by three test structures at the X-band fabricated on a GaN technology. The experimental results show that a small size and wideband 50-load with a return loss better than 25 dB can be obtained, while the resistor value changes ±30%.

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