Danish Kalim

Concurrent planar multiharmonic dual-band load coupling network for switching-mode power amplifiers

This paper presents a concept to design a compact planar multiharmonic load transformation network (MHLTN) for the realisation of highly efficient dual-band power amplifiers (PAs). The proposed MHLTN consisting of only transmission-lines can precisely achieve impedance terminations at two distinct nonharmonic frequencies including up to three harmonics without switches or tuning elements. High impedance stubs are deliberately inserted at particular sections of the network for the harmonic frequency termination to be controlled. The topology was applied to implement a class-E PA using a GaN High Electron Mobility Transistor (HEMT) in a hybrid design for GSM1810 and LTE2655 operation. The measured impedances of the passive switchless MHLTN for a dual-band class-E load coupling network are in good agreement with simulation results. With a dual-band input matching network, the measurement results have shown 78.4% and 61.3% of peak power added efficiency (PAE) with an associated output power of 37.8dBm and 36.9dBm in the lower and upper band, respectively.

Analysis and design of an unconditionally stable common-drain class-B RF power amplifier in 90 nm CMOS technology

Modern communication networks demand power amplifiers (PAs) which are efficient and have low distortion. The common drain amplifier has the potential to become a linear amplifier with good efficiency, when biased at or above class-B. The main challenge is to provide unconditional stability while still maintaining adequate transducer gain so that the power added efficiency (PAE) will not be compromised by low gain and, thus, resulting in better overall performance. In this contribution, analysis and design of an unconditionally stable common drain class-B PA for the LTE band at 2.55 GHz in 90 nm CMOS is presented. The simulation results show that the designed PA can deliver an output power of more than 27.2 dBm with gain of 6.1 dB and PAE greater than 43.0 % when operated from 2.5 V supply. The circuit has a third order intermodulation distrotion suppression of 32.0 dBc at 3 dB input back-off.

Investigation of Wideband Load Transformation Networks for Class-E Switching-Mode Power Amplifiers

In this paper, single-ended and differential class-E load transformation networks (LTNs) for wideband operation are investigated. For this purpose, a differential third parallel-tuned tank LTN and a parallel-circuit load LTN without suppressing tanks are proposed to fulfill the class-E wideband condition. The differential parallel-circuit load (DPCL), which considers the finite RF chokes, has higher output resistance, and because of the differential structure, which ensures an open circuit at even harmonic frequencies, it is able to cover a wide frequency range. Consequently, the DPCL is well suited for highly integrated monolithic designs, as well as wideband application. Based on this analysis, a wideband class-E switching-mode power amplifier in CMOS 90 nm using the DPCL is designed. By deliberately combining the LTN with an on-chip balun, a compact size of 1.2 mm2 is achieved. The circuit performance dependency on bond-wire length variation is analyzed and discussed. Measured results show a peak output power of 28.7 dBm, power-added efficiency (PAE) of 48.0%, and drain efficiency of 55.0% at 2.3 GHz. From 1.7 to 2.7 GHz, PAE is higher than 42% and output power is above 25 dBm.

Study on load transformation networks for differential common drain class-B RF power amplifier

Common drain class-B PAs have the potential of providing high linearity and efficiency. This work analyses the performance of differential common drain class-B power amplifiers (PAs) in terms of linearity, efficiency and time-domain waveforms depending on the load transformation network (LTN) used. Four different LTNs, which provide the required impedance conditions for class-B operation are analysed and the circuit performance of common drain PAs is verified and compared in simulations. The transformer based LTN shows maximum linearity due to the high degree of symmetry. Third-order intermodulation distortion, IMD3 at 3 dB output power back-off from 1 dB compression point, P1dB is 36 dBc while second harmonic rejection is 103 dBc at an input power of 20 dBm. Peak power added efficiency, PAE of 40.6 % was achieved with this configuration. An equivalent off-chip load network achieves peak PAE of 30 % with IMD3 rejection of 31 dBc at 3 dB back-off from P1dB and second harmonic rejection of 24.7 dBc for an input power of 20 dBm. A compromise between area and integration complexity can be obtained with the other two designs analysed. The results confirm that differential common drain class-B PAs have the potential of providing good linearity also for modern digitally modulated signals.

Broadband CMOS class-E power amplifier for LTE applications

High level integration for system on chip (SOC) applications motivates the development of broadband power amplifiers (PAs) in low cost CMOS technology to reduce size and power consumption of any wireless system. However, integration of one of the key components in a transmitter-the PA still remains a challenge. In this paper, a single stage broadband class-E PA based on lumped element load transformation network (LTN) in 90nm CMOS technology for LTE band i.e. 2.67 GHz is presented. The simulations with a 2.5V supply voltage show that the designed PA can deliver an output power (Pout) of 22.9dBm with an associated power gain (G) of 8.9 dB and power added efficiency (PAE) of 60.4 %. A PAE of more than 55 %, output power of 21.5dBm and a gain of more than 7.5 dB was achieved over a wide bandwidth i.e. from 2.3GHz to 3.3 GHz. The frequency range also covers wireless local area network (WLAN) and bluetooth applications.

A 3.3 GHz class-E power amplifier with 77% PAE utilising GaN HEMT technology

High efficiency with high power amplification is of great concern in modern wireless communication systems to increase battery life and reliability. GaN Heterojunction Electron Mobility Transistors (HEMT) have found widespread applications in RF/microwave power amplifiers (PAs) to fulfill these requirements. In this paper, a transmission-line based class-E PA is designed in GaN HEMT technology at 3.3 GHz. The implemented load transformation network (LTN) of the PA separates the DC biasing and the second harmonic termination into two sections as compared to conventional LTN for class-E PAs to attain high efficiency. Measured impedances of the passive LTN are in good agreement with the desired values. Measurement results of the class-E PA show peak power added efficiency (PAE) of 76.9% and peak output power of more than 38.0 dBm, when operated from a 28V supply.

Dual-band 1.7 GHz / 2.5 GHz class-E power amplifier in 130 nm CMOS technology

The evolution of new mobile communication standards demand highly efficient multiband power amplifiers (PAs) both in mobile equipments and base stations. This paper presents a concept for a compact multiharmonic load transformation network (MHLTN), appropriate for a fully integrated differential dual-band PA design in an RF front-end transmitter. The proposed MHLTN was applied to implement a dual-band class-E PA based on finite DC-feed inductance in a 130 nm CMOS process for GSM1700 and LTE2500 operation. With a dual-band input matching network, simulation results have shown peak power added efficiency (PAE) and peak output power of more than 57% and 27 dBm, respectively, at both bands. The designed PA is also able to cover a wide frequency range. From 1.4 GHz to 2.7 GHz, output power is above 25 dBm and PAE is higher than 50 %.

Switching-Mode Differential Class-B Amplifier for Phased Array Radar

Switching-mode power amplifiers are used in applications where linearity is not critical and efficiency is the utmost priority e.g. phased arrays. This paper presents the design of a differential class-E amplifier for a phased array radar application in 0.25, ¿m SiGe BiCMOS technology. The operating frequency range is 2.9 GHz to 3.1 GHz with center frequency at 3GHz. The design approach of the amplifier which includes damping circuit, shunt charging capacitor and balun will be described, Simulations of the design predict an output power and PAE of 25.8 dBm and 49 % respectively. The output stage is biased with a 3.3 V at the collector.