AN-1162| Application Note

Using the LMX3162 for 2.4-GHz ISM Band

Using the LMX3162 for 2.4-GHz ISM Band
TABLE OF CONTENTS 1.0 ABSTRACT 2.0 INTRODUCTION 3.0 STANDARDS 4.0 TRANSCEIVER DESIGN 4.1 SYNTHESIZER 4.1.1 Lock Time 4.2 TRANSMITTER 4.3 RECEIVER 4.3.1 Demodulation Parallel Tank 4.3.2 Performance 5.0 CONCLUSION LIST OF FIGURES FIGURE 1. Transceiver Blocks FIGURE 2. Timing for Open Loop Operation FIGURE 3. Ultra Low Drift PLL FIGURE 4. PLL Lock Time FIGURE 5. Open Loop Frequency Drift at 85 C FIGURE 6. Bluetooth Modulated Signals FIGURE 7. (a) Tx Block. (b) Rx Block FIGURE 8. Harmonics of Transmitter Output FIGURE 9. Phase Noise of Local Oscillator FIGURE 10. LNA/PA in Low-Power Mode FIGURE 11. Receiver Chain Analysis FIGURE 12. Quadrature Demodulation FIGURE 13. Parallel Quadrature Tank FIGURE 14. Eye Diagram, BER = 1e-3, -83 dBm FIGURE 15. Eye Diagram, BER = 0, -40 dBm FIGURE 16. Eye Diagram for Bluetooth CCI Test FIGURE 17. Eye Diagram for Bluetooth ACI 1-MHz Test FIGURE 18. Eye Diagram for Bluetooth ACI 2-MHz Test. (-81 dBm) FIGURE 19. Eye Diagram for Bluetooth ACI 3-MHz Test. (-72 dBm) FIGURE 20. Blueto
oth Intermodulation Test FIGURE 21. Optional LNA/PA for Bluetooth or HomeRF/Upbanded DECT FIGURE 22. Optimized Schematics of LMX3162 Evaluation Board (include Tx buffer) LIST OF TABLES TABLE 1. Parameter Comparison for 2.4-GHz Applications TABLE 2. Interference Test for Bluetooth TABLE 3. Bill of Materials for LMX3162

National Semiconductor AN-1162 Wireless Communication January 2000

1.0 ABSTRACT A monolithic radio transceiver will be demonstrated for the emerging wireless data and voice applications in the unlicensed 2.4-GHz ISM band including Bluetooth, HomeRF and Upbanded DECT standards. The architecture and the functionality of the LMX3162 will be described thoroughly. The circuit blocks and the topology will be discussed to implement the complete radio with the measuring performance. These results illustrate the single-chip LMX3162 is a possible solution to support the various standards in ISM band. 2.0 INTRODUCTION Higher and higher levels of integration in RF circuits have become the trend over the past decade. For example, the complete receiver on a chip has been available in the industries for many years ago. The LMX3162 integrated circuit (IC) takes radio integration one step further by including receiver, transmitter, and the phase locked loop (PLL) on the same piece of silicon. In accordance with a 1.3-GHz PLL, a frequency doubler is employed and both the receiver and the tra
nsmitter can share the same PLL. This reduces the complexity of the system as well as avoiding the problem of injection locking or LO pulling in the VCO. Figure 1 shows a typical implementation of a 2.4-GHz radio front-end transceiver. In addition to the PLL and frequency doubler, a 2.5-GHz low-noise mixer, intermediate-frequency (IF) amplifier, limiting amplifier, frequency discriminator, and receivedsignal-strength indicator (RSSI) for the receiver, as well as a buffer amplifier for the transmitter are integrated in LMX3162[1][2]. Only a few of channel selection filters, VCO and loop filters are required external components1. The discrete low noise amplifier (LNA) and power amplifier (PA) are optional depending on system requirements for the various standards and applications. New standards have been developed for the exploding Home PC, handheld service access and information appliance market. For this reason, the unlicensed 2.4-GHz Industrial, Scientific and Medical (ISM) band has been received a great am
ount of interest in the wireless communications industry worldwide. The common frequency range (2.4 GHz to 2.483 GHz) in Europe, Japan and the USA has also made this band attractive to many product manufacturers. Several companies have their own solutions available in the market today. The open standards will guarantee inter-operability between products of different brands as well as gain customer acceptance and market penetration. Recently, there has been much activity developing products based on Bluetooth and HomeRF protocols.[3][4] The VCO regulator and biasing capacitors are not included here.
1

AN-1162

MICROWIRETM is a trademark of National Semiconductor Corporation.

2000 National Semiconductor Corporation

AN101312

www.national.com