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The RF receiver front end was fabricated using a standard PCB process (Fig. 6) and was evaluated with the aid of commercial test equipment. The measurement system included a model SMF100A signal generator, a model ZVA40 vector network analyzer (VNA), a model FSUP signal source analyzer, and a model FSQ signal analyzer, all from Rohde & Schwarz, and a model E8267D signal generator with option H44 from Agilent Technologies. Measurements were made of a variety of performance parameters, including gain, gain flatness, input VSWR, noise figure, image rejection, and input 1-dB compression point, with summaries presented in Table 3. The input 1-dB compression point for the entire system was measured at -20.1 dBm, as shown in Fig. 7 (a 20-dB attenuator was added at the IF port of the RF front end during the test to protect the input port of the model ZVA40 VNA).

Low-Cost Front End  Receives 9 GHz, Fig. 6

Low-Cost Front End  Receives 9 GHz, Table 3EVM is a figure of merit often used to quantify the performance of a digital radio transmitter or receiver. Noise, distortion, spurious signals, and phase noise all degrade EVM; therefore, EVM provides a comprehensive measure of the quality of the radio receiver or transmitter in digital communications applications. Figure 8 shows the EVM performance of the RF receiver front end with 16-state quadrature-amplitude-modulation (16QAM) signals. When the input power of RF signal is -30 dBm and the bandwidth is 20 MHz, the EVM levels of the RF receiver front end with 16QAM and quadrature-phase-shift-keying (QPSK) signals are 3.3% and 3.1%, respectively. When the signal source is connected directly to the test signal analyzer, the EVM is about 2%, indicating excellent RF front-end performance.

Low-Cost Front End  Receives 9 GHz, Fig. 7

Low-Cost Front End  Receives 9 GHz, Fig. 8

As these results reveal, the receiver front end is well suited for mobile communications within this higher-frequency band. In addition, due to its extremely low cost, the proposed front end is suitable for large-scale applications, such as in multiple-input, multiple-output (MIMO) systems.

Acknowledgments

This work was supported in part by the National Natural Science Foundation of China under Grant No. 60702163, and in part by the National Science and Technology Major Project of China under Grant Nos. 2010ZX03007-002-01 and 2011ZX03004-003.

Lina Cao, Master’s Candidate

State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, Jiangsu, 211111, People’s Republic of China; +86-15850608372

Jianyi Zhou, Professor

State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, Jiangsu, 211111, People’s Republic of China; +86-025-52091653-401

Dahai Ni, Master’s Candidate

State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, Jiangsu, 211111, People’s Republic of China; +86-15151859518

Shun Zhao, Master’s Candidate

State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, Jiangsu, 211111, People’s Republic of China; +86-15850670606

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