2.4GHz ISM頻帶功率放大器與有線電視頻域多工交換網路頻率合成器

Abstract

本篇論文分為兩部份: 一為供無線區域網路用2.4GHz ISM頻帶功率放大器 ﹔一為供有線電視頻域多工交換網路用頻率合成器模組﹐提供交換網 路616-676MHz, 682-742MHz, 748-808MHz與81-100MHz四組本地信號頻率 。2.4GHz ISM頻帶功率放大器是一採用AB類偏壓的三級放大器﹐第一級是 以雙載子接面晶體製作﹐第二級與第三級以砷化鎵場效電晶體製作。其P1 dB點達27dBm﹐增益在0dBm的輸入功率時為27dB。根據美國聯邦通訊委員 會在Part 15.209及12.249的諧波及雜波規範﹐我們設計了諧波濾波器以 抑制發射諧波的含量﹐第二次與第三次諧波抑制分別達46dBc與50dBc以上 。除此﹐在實際量測接收諧波時﹐我們設計了基波濾波器於接收端的前置 放大器前﹐以避免前置放大器因基波飽和失真而引起的量測不準。此功率 放大器的電路大小僅為16X16.5X0.4 (mm)。為求振盪頻率精確與穩定﹐採 用由壓控振盪器加鎖相迴路構成之頻率合成器。在壓控振盪器後加上緩衝 放大器﹐以改善負載拉昇效應及增加功率輸出﹐另外為節省電路面積採用 National LMX1501A鎖相迴路積體電路。我們採用混成式微波積體電路技 術製作﹐並以C語言撰寫由RS232C控制的介面程式。整個頻率合成器模組 由四個頻率合成器與其金屬封裝組合﹐單一頻率合成器的大小為57X35X20 (mm)。其輸出功率大於1dBm﹐且此四個頻率合成器的相位雜訊離載波頻率 在10KHz與100KHz均分別小於-90dBc/Hz與-110dBc/Hz。 In this report, we present a 2.4GHz ISM band power amplifier for wireless LAN and four frequency synthesizers for CATV FDM switching network that provides 616-676MHz, 682-742MHz, 748-808MHz and 81-100MHz frequencies band. The 2.4GHz power amplifier is a three-stage amplifier that bias at class AB. The first stage is a silicon BJT and the second and the third stages are GaAs MESFET amplifiers. The P1dB of the power amplifier is 27dBm and its gain is 27dB when the input power is 0dBm. Due to the maximum permitted harmonics/spurs of the FCC part 15.209 and 15.249, we designed a harmonic rejector to suppress the output harmonics power. In addition, we designed a fundamental rejector in front of the preamplifier to avoid the preamplifier saturation at the receiving end. The size of the power amplifier module is miniaturized to a mere 16X16.5X0.4 (mm). For precise and stable oscillation frequency, we use VCO and PLL to compose a frequency synthesizer. We add a buffer amplifier to the VCO part in order to improve the load pulling effect. In addition, we use a PLL IC □National LMX1501A as the PLL part which can save the circuit size. We combined the four synthesizers to a synthesizer module using hybrid MIC technology. This synthesizer is controlled by a Turbo C program through the RS232C interface. The volume of each frequency synthesizer with its housing is 57X35X20 (mm). The output power is larger than 1dBm and the phase noise of these four synthesizers are less than -90dBc/Hz and -110dBc/Hz at 10KHz and 100KHz offset, separately.