Communications on Applied Electronics |
Foundation of Computer Science (FCS), NY, USA |
Volume 2 - Number 4 |
Year of Publication: 2015 |
Authors: Marwa Mansour, R.S. Ghoname, Abdelhalim Zekry |
10.5120/cae2015651698 |
Marwa Mansour, R.S. Ghoname, Abdelhalim Zekry . Building Radio Frequency Transmitter for LTE User Equipment. Communications on Applied Electronics. 2, 4 ( July 2015), 1-9. DOI=10.5120/cae2015651698
Software defined radio implementation is required for LTE radio transceivers. An SDR consists of an RF front end and a digital processor platform DSP. This paper is devoted to the design and implementation of the front end which is divided into an active and a passive front end. The active front end consists of a frequency synthesizer, an I/Q modulator and an RF power amplifier while the passive front end includes the antenna and band pass filter. The paper presents the design, implementation, and testing of the LTE transmitter where the passive front end components are made of a microstrip circuits while the active components are selected from the off shelf components available in the semiconductor market. For this, the antenna and filter were printed using FR-4 substrate material with dielectric constant of ɛr =4.4, thickness of h = 1.6 mm and loss tangent tan δ = 0.025. The frequency synthesizer is selected with step size of 200 KHz and frequency range from 0.37GHz to 5.7GHz, so that it covers all LTE bands. The selected direct conversion I/Q modulator has frequency range from 0.2GHz to 6GHz. It allows direct modulation of an RF signal using differential baseband I and Q signals. The selected RF Power Amplifier has two modes of operation, a high power mode (HPM) and low power mode (LPM).The PA achieves gain of about 25.5 dB and 14.5 dB in HPM and LPM respectively over the 60 MHz bandwidth from 1920MHz to 1980MHz. The performance of each component and the whole transmitter is measured using VNA (E8719A), EXA X-Series Signal Analyzer (N9010A), Agilent E8267D PSG Vector Signal Generator, and spectrum analyzer.