A switchless reconfigurable transformer CMOS power amplifier

Abstract

Abstract:A reconfigurable dual-mode monolithic transformer is presented, which avoids the use of switches for load adaptation. The number of turns of primary winding is varied according to power mode control so that load impedance can be optimized for each operation. The concept of the reconfigurable transformer is demonstrated through the design of a multi-mode power amplifier using bulk CMOS process. Electromagnetic and circuit simulation results validate the operation and performance improvements using the proposed transformer. Low power efficiency at 18 dBm is substantially improved from 5.5% to 17.5% using multi-mode control.

An on‐chip low‐loss reconfigurable transformer for multimode power amplifiers

“…For the multimode operation, power combining‐based transformers (ie, parallel‐combining transformer and series‐combining transformer) have been introduced. Because of nonoptimal operation of the LP mode in the power combining‐based transformer, the concept of a reconfigurable transformer has been presented without implementation to improve the operation in both modes in our previous work …”

“…Because of nonoptimal operation of the LP mode in the power combining-based transformer, the concept of a reconfigurable transformer has been presented without implementation to improve the operation in both modes in our previous work. 4 In this work, an analysis of the proposed reconfigurable transformer is presented for multimode operation. In addition, a segment-based lumped model is introduced to estimate its performance accurately.…”

A reconfigurable monolithic step‐up autotransformer

“…The output matching can provide higher input impedance at a lower PA output power and a lower input impedance at a higher PA output power for optimum operation. Many studies on multimode operation using two‐winding transformers are under way . Further, the concept of a reconfigurable autotransformer has been introduced in our previous study .…”