Ki Seok Yang

Power-Combining Transformer Techniques for Fully-Integrated CMOS Power Amplifiers

Fully integrated CMOS power amplifiers (PAs) with parallel power-combining transformer are presented. For the high power CMOS PA design, two types of transformers, series-combining and parallel-combining, are fully analyzed and compared in detail to show the parasitic resistance and the turn ratio as the limiting factor of power combining. Based on the analysis, two kinds of parallel-combining transformers, a two-primary with a 1:2 turn ratio and a three-primary with a 1:2 turn ratio, are incorporated into the design of fully-integrated CMOS PAs in a standard 0.18-mum CMOS process. The PA with a two-primary transformer delivers 31.2 dBm of output power with 41% of power-added efficiency (PAE), and the PA with a three-primary transformer achieves 32 dBm of output power with 30% of PAE at 1.8 GHz with a 3.3-V power supply.

Low-Loss Integrated-Waveguide Passive Circuits Using Liquid-Crystal Polymer System-on-Package (SOP) Technology for Millimeter-Wave Applications

In this paper, we show a low-loss integrated waveguide (IWG), microstrip line-to-IWG transition, IWG bandpass filter (BPF), and system-on-package (SOP) using a liquid-crystal polymer (LCP) substrate, which can be used toward SOP technology for millimeter-wave applications. The proposed IWG can be used as a low-loss millimeter-wave transmission line on this substrate. The measured insertion loss of the IWG is -0.12 dB/mm and the measured insertion loss of two microstrip line-to-IWG transitions is -0.14 dB at 60 GHz. The evaluated IWG filter is demonstrated as the pre-select filter for RF front-end modules at the millimeter-wave band. The fabricated three-pole BPF at a center frequency of 61.1 GHz has specifications: a 3-dB bandwidth of approximately 13.4% (~8.4 GHz), an insertion loss of -1.8 dB at the center frequency of 61.1 GHz, and a rejection of >15 dB over the passband. The proposed IWG can also be used as a low-loss millimeter-wave feed-through transition and interconnection between the monolithic microwave integrated circuit and the module instead of the vertical via structure. In terms of a SOP on LCP for millimeter-wave applications, the top face of the IWG does not have any electromagnetic effects, and a package lid can be attached to provide a hermetic sealing. These low-loss IWG circuits on LCP can easily be used in many millimeter-wave packaging applications

A Monolithic Voltage-Boosting Parallel-Primary Transformer Structures for Fully Integrated CMOS Power Amplifier Design

In this paper, a novel monolithic voltage-boosting parallel-primary transformer is presented for the fully integrated CMOS power amplifier design. Multiple primary loops are interweaved in parallel to combine the AC currents from multiple power devices while the higher turn ratio of a secondary loop boosts AC voltages of the combined primary loops at the load of the secondary loop. The proposed interweaved structure is much more compact and separable from power devices, avoiding potential instability. To verify the feasibility of this power combining method, the fully integrated CMOS switching power amplifier was implemented in a standard 0.18-mum technology. The power amplifier successfully demonstrated a measured output power of 1.3 W and a measured power added efficiency (PAE) of 41% to a 50-Omega load with a 3.3-V power supply at 1.8 GHz operation.

A 1.8-GHz 2-Watt Fully Integrated CMOS Push-Pull Parallel-Combined Power Amplifier Design

This paper newly presents a push-pull parallel-combined CMOS power amplifier (PA) and its analysis of operation. The proposed class-E CMOS PA incorporates the push-pull parallel-combined power devices with the 1:1:2 (two single-turn primary windings and a two-turn secondary winding) step-up on-chip transformer. The PA is fully integrated in a standard 0.18-mum CMOS technology without any external balun or matching networks. The operation of the PA with a multi-turn on-chip transformer is substantially analyzed in order to optimize the device size and its structure. Experimental data demonstrates the output power of 2-watt and the power-added efficiency (PAE) of more than 30% with a 3.3-V of power supply at 1.8 GHz. This is the new demonstration of the compact fully integrated CMOS PA with 2-watt of output power with very stable operation at 1.8 GHz range.

Slot array antennas fed by integrated wave guide on liquid crystal polymer for V-band wireless LAN application

In this paper, the two slot array antennas fed by integrated waveguide are proposed and designed on liquid crystal polymer to reduce the transmission loss of the feeding line and enable an easy integration. For 60 GHz wireless LAN applications, a high antenna gain is required to overcome the propagation loss. Also, we investigated fan beam antenna topology to maximize the azimuth coverage. Antenna gains about 10 dBi has been achieved using 5 and 7 slots array configuration. The numerical analysis shows the proposed antennas can be a good candidate for 60 GHz wireless LAN application.