Geunyong Lee

A Multiband Power Amplifier With a Reconfigurable Output-Matching Network for 10-MHz BW LTE Mobile Phone Applications

A single-chip power amplifier (PA) with a reconfigurable output-matching network is presented for fourth-generation multiband mobile phone applications. The multiband PA (MBPA) consists of an amplifier and a reconfigurable output-matching network [a band selection circuit (BSC) and a tunable transmission line (TTL)]. Multiband load-impedance modulation is done by controlling a p-i-n switch of the BSC and varactor diodes of the TTL in the reconfigurable output-matching network. This MBPA delivered a gain of more than 11 dB, an adjacent channel leakage ratio of the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (E-UTRA) smaller than -32 dBc, and a power-added efficiency larger than 29% at the output power of 26 dBm for high and low frequency bands with a 10-MHz 16-quadrature amplitude modulation Long-Term Evolution signal.

A Lumped-Element Directional Coupler With High Isolation for Mobile RFID Reader

A lumped-element directional coupler with a high isolation characteristic for mobile RFID reader systems is proposed and experimentally demonstrated. Compared with the conventional lumped-element circuit, the proposed structure utilizes compensation capacitors and achieves a very high isolation despite low quality factor on-chip inductors. It was fabricated on a high-resistivity silicon substrate and showed an isolation of 79 dB, a coupling level of 14.8 dB, and an insertion loss of 1.74 dB at 910 MHz.

A single chip multiband power amplifier using active load modulation techniques

This paper presents a single chip multiband power amplifier (MBPA) using a proposed active load modulation (ALM) technique. Based on Doherty PAs concept, the single chip MBPA consists of a main amplifier, an auxiliary amplifier, and transmission lines connecting two amplifiers to modulate the main amplifiers load line over the frequency. The ALM technique achieves the desired load line at specific frequency band by three parameters; RF current ratio of the main amplifier to the auxiliary amplifier (α), a characteristic impedance (ZT) and an electrical length (θ) of a transmission line. The fabricated single chip MBPA operates from 1.6 to 2 GHz with over a 10 dB of gain using the proposed ALM technique. It shows 35.5 % of power added efficiency (PAE), and 25.5 dBc of adjacent channel leakage ratio (ACLR1) at 27 dBm output power with the 10 MHz BW 16QAM LTE signal from 1.6GHz to 2GHz.

A SiGe BiCMOS Power Amplifier Using a Lumped Element-Based Impedance Tuner

A dual-path multi-band power amplifier (PA) with a tunable output matching network is presented for long-term- evolution (LTE) handset applications. To optimize output load impedances for various power regions with various frequency bands, an impedance tuner implemented using lumped elements is used. The dual-path multi-band PA fabricated using 0.35-μm SiGe BiCMOS process is evaluated for the evolved UMTS terrestrial radio access (E-UTRA) bands 1, 2, 3, 5, and 8 with a 10 MHz bandwidth (BW) LTE 16 quadrature amplitude modulation signal having a peak-to-average ratio of 6.4 dB.

A parallel power amplifier with load impedance transformation for optimized low power performance

This paper presents analytic expressions for T-type chain matching network synthesis of the power amplifier (PA) to enhance the performance at low output powers via a load impedance adjustment. Here, a parallel power amplifier for WCDMA B1 (1920-1980MHz) based on an InGaP/GaAs hetero-junction bipolar transistor (HBT) is utilized, which has a fully integrated matching network on a printed circuit board (PCB). As a result, the power amplifier shows a 38.7% power added efficiency (PAE), and a -37dBc adjacent channel leakage power ratio (ACLR) at 27.5dBm output during high power mode operation, and 17.6% PAE with a 22mA quiescent current and a -40.7dBc at a back-off output power of 17dBm during low power mode.

A directional coupler with suppressed Tx leakage for UHF RFID reader applications

A directional coupler with a high isolation characteristic for radio frequency identification reader systems is presented. Compensation capacitors are used to improve the inherently poor isolation of a microstrip directional coupler due to unequal even- and odd-mode phase velocities. The transmitter leakage signal, which is reflected by the mismatch of the antenna impedance, is substantially reduced by optimization of the compensation capacitor values and the value of an additional resistor attached to the coupling port. The proposed directional coupler exhibits an isolation of 76.8 dB, a coupling factor of 16.6 dB, and an insertion loss of 0.28 dB for a matched antenna impedance at 910 MHz. It also has an isolation of more than 60 dB for mismatched antenna load impedances corresponding to a reflection coefficient of 0.33 at 910 MHz.