Zhebin Hu

Design of Broadband Linear and Efficient Power Amplifier for Long-Term Evolution Applications

In this letter, a broadband linear and efficient power amplifier for base-stations in long-term evolution (LTE) applications is designed, fabricated, and experimentally verified, employing Crees CGH40010F GaN HEMT. A novel method of baseband, fundamental and harmonic impedances control is used to provide high linearity and efficiency across a broad bandwidth. When producing a two-tone carrier-to-intermodulation ratio (C/I) of 30 dBc, the circuit has demonstrated a two-tone power added efficiency (PAE) between 45%-60% across the frequency range from 1.6 to 2.6 GHz while delivering 36.0-38.5 dBm average output power. For a single-carrier 20 MHz LTE signal with a peak-to-average ratio (PAR) of 6.5 dB, a measured high PAE of 40%-55% can be achieved at an average output power of 35.3-37.5 dBm with an adjacent channel leakage ratio (ACLR) of about -30 dBc from 1.6 to 2.6 GHz.

Analysis of a Broadband High-Efficiency Switch-Mode

In this paper, a broadband high-efficiency supply modulator is proposed. This modulator, with a node controlled by ΔΣ modulators output, consists of a conventional Class-E amplifier and a Class-E rectifier. The configurations and operation principles of this modulator are introduced to explain the envelope reconstruction process. The performance of this modulator in steady state is analyzed to show the reason for high-efficiency operations assisted by a shunt diode, especially for short-circuited load resistance. Its performance for broadband envelopes amplification is analyzed using numerical difference equations. The results show that efficiency degradation and nonlinearity of this modulator are inevitable due to transient responses. The most significant factors related to the performance degradation, such as switch loss and conduction loss, are determined and verified by numerical simulations. The simulations for one-carrier wavelength code-division multiple-access (WCDMA) envelopes show that over 80% average efficiency and normalized mean square error (NMSE) of -16 dB can be obtained in numerical examples even considering the nonidealities. An experimental supply modulator is given to verify the proposed modulator. In this experiment, 48.6% average efficiency and NMSE of -15.9 dB are measured for WCDMA envelopes of 6.1-dB peak-to-average-power ratio.

\Delta \Sigma

This paper introduces a novel matching network synthesis method that matches arbitrary impedance at three independed frequencies to 50 Ohm. By converting impedance matching to admittance matching, the matching work can be divided into two steps. Modified T-type topology for triple band admittance matching is discussed based on ABCD-parameters, and the formulas of matching networks are analytically derived. Finally, the proposed synthesis approach is validated with the design and simulation of a tri-band matching network at 900, 1900 and 2400 MHz.

Supply Modulator Based on a Class-E Amplifier and a Class-E Rectifier

This paper presents a 80W high gain and broadband Doherty power amplifier (DPA) with symmetrical devices, employing Wolfspeeds CGHV27030S GaN HEMT. A novel architecture is used to eliminate the complex interaction of varying second harmonic impedances caused by active load modulation and provide high efficiency at output back-off (OBO) region and saturation point. Under a 10% duty cycle pulse excitation from 3.35-3.50 GHz, experimental results show the proposed DPA delivers 49.1-49.5 dBm output power with a drain efficiency (DE) of 50.2%-55.1% at 8 dB OBO and achieves a gain of 14.6-14.9 dB at an output power of 41 dBm. When extend the bandwidth to 3.3-3.6 GHz, the DPA can attain a measured DE higher than 40.9% at an OBO of 8 dB with a saturated power of 48.5-49.5 dBm. For a 2-carrier 40-MHz long-term evolution (LTE) signal with a peak-to-average power ratio (PAPR) of 8 dB, the adjacent channel leakage ratio (ACLR) is -30 dBc at 41 dBm average output power at 3.45 GHz.

Tri-band matching technique based on characteristic impedance transformers for concurrent tri-band power amplifiers design

This paper presents the design, implementation and measurement results of a high efficiency harmonic tuned PA at 2.85GHz using a high power GaN HEMT transistor. Based on large signal equivalent circuit model and computer-aided design tools, optimum fundamental and harmonic impedances are obtained to maximize PAE. The compromise between PAE and complexity along with proper selection of matching circuit topology simplify design and adjustment procedure, and also reduce the dimension of circuit. With the stimulus of continuous wave, the measurement results show a maximum power-added efficiency of 82.2%, a maximum drain efficiency of 86.6%, a power gain of 12.91dB with 39.91dBm output power.

A 80W high gain and broadband Doherty power amplifier for 4/5G wireless communication systems

In this paper, we present a concurrent tri-band power amplifier by using a tri-band matching network synthesis method. At the package plane, a cross-type impedance transformer and susceptance matching network are placed in parallel to realize the desired admittance at three independent frequencies. Design equations of the different possible topologies are present based on ABCD-parameters. Then, the proposed synthesis approach is validated with the design of a tri-band power amplifier at frequency bands 0.90, 1.85 and 2.40GHz. For a continuous-wave measurement, the peak drain efficiency is 70.0%, 67.1% and 59.8% at 0.90, 1.85 and 2.40GHz, respectively.