| Amplifier is a basic circuit of radio frequency circuit communication system,it can amplify the signal and provide a certain power gain.In the radio frequency transmitting system, the amplifier is responsible for providing the sufficient power of the radio frequency signal output; in the radio frequency receiving system, the amplifier is responsible for the weak signal amplifier. With the popularity of 4G networks, multi-mode multi-standard compatible system work more and more demand, thus promoting the research of amplifier which can work in multi-frequency.The RF amplifier used in this paper is the MW6S004N chip of Freescale company. The circuit design and simulation of single frequency and dual band power amplifier is completed in the paper with ADS software. Finally we make implementation of the 1.96GHz single frequency RF amplifier and 0.9/1.96GHz dual band RF amplifier. This paper has completed the following aspects of the work:(1) The single frequency RF amplifier used a matching network about a hybrid parameter. Dual band RF amplifier selected π-type structure of the impedance converter and a section of transmission line matching network, the transmission line is two frequency complex impedance transform conjugate complex impedance, the impedance converter of π-type structure is the complex conjugate impedance and 50 ohm impedance matching.(2) The paper realizes the 1.96GHz single frequency RF amplifier, after constant adjustment of the shunt capacitance value and its position, the amplifier in the 1.96GHz has about 57MHz bandwidth, the output power can reach 4W. Small signal gain can reach more than 17dB, gain flatness also meet the requirements.(3) The 0.9GHz and 1.96GHz dual band RF amplifier is realized in this paper. From the beginning of the MW6S004N1 pipe to the static working point of the design simulation to the final PCB board production, which contains the dual band RF amplifier bias circuit, the DC circuit and the design of the input and output matching network. The amplifier has a bandwidth of about 51 MHz and 55MHz in two bands, and the output power is up to 4W at two frequencies. Gain and flatness are basically satisfied.By means of small signal and large signal test, the test data and simulation are compared and analyzed. The measured results are in good agreement with the theoretical simulation, which shows that the design of the RF amplifier has a good practical value. |
