20百萬赫茲雙相位切換頻率之電流恆定導通模式直流降壓轉換器設計

Abstract

穩壓器在現今的電子應用中是不可或缺的電路，其中直流轉換器因為具有良好的效率因此被廣泛使用，然而，傳統的降壓轉換器因為需要使用龐大的晶片外電感及電容，造成了系統面積增加及額外走線導致的效率損耗，因此，使用晶片上或封裝內電感來實現直流降壓轉換器已經成為學術與商業產品的一個重要發展方向。 本文針對與封裝內電感相容的整合式穩壓器應用，提出了一個應用47nH電感、雙相位、兩千萬赫茲切換頻率的新式電流恆定導通模式的直流降壓轉換器，在此設計中，成功實現了雙相位控制，且不依賴額外的相位管理邏輯電路，因此降低了這些額外的效率與面積損失，除此之外，傳統的電流恆定導通模式中，切換頻率會隨著輸出電壓改變的問題也在此設計中一併成功被解決。 此晶片使用TSMC 0.18 um CMOS Mixed Signal RF General Purpose Standard Process FSG Al 1P6M 1.8&3.3V製程設計製造。最終轉換器達到83.4%的峰值效率，在負載瞬態響應測試中，電流步進的斜率為360mA/0.4μs，並展現出優異的暫態響應，輸出電壓具有13.5mV的下衝與16mV的上衝，以及1.24μs與1.64μs的恢復時間。

Voltage regulators (VRs) are essential components in nearly all electronic devices, with the DC-DC converter being frequently utilized due to its superior power efficiency. However, traditional buck converters often rely on bulky, discrete off-chip inductors and capacitors, which incur a large form factor and contribute to efficiency loss due to parasitic routing effects. Consequently, implementing DC-DC converters with on-die or on-package inductors has become a crucial design paradigm for both academic research and commercial products. A novel control technique for a 2-phase, 20 MHz CMCOT buck converter using 47nH inductor is presented for integrated voltage regulator (IVR) applications compatible with on-package inductors. A key achievement of this work is the successful implementation of the 2-phase CMCOT control without relying on redundant phase management logic circuits, thus avoiding unnecessary power and area costs. Furthermore, the inherent issue of the switching frequency varying with the output voltage—a common drawback of traditional CMCOT—is also successfully resolved in this design. Designed and implemented in the TSMC 0.18 µm CMOS Mixed Signal RF General Purpose Standard Process FSG Al 1P6M 1.8&3.3V, the resulting converter achieves a peak efficiency of 83.4%. Load transient measurements, tested with a current step slew rate of 360mA/0.4μs, demonstrate an excellent transient response, featuring a 13.5mV output voltage undershoot and a 16mV overshoot, with a recovery time of 1.24μs and 1.64μs.