A High Gain Low Noise Mixer with Low Power Consumption for WLAN Application and A Triple Band Circularly Polarized Antenna
Jou, Christina F.
|關鍵字:||無線區域網路;低功耗;三頻圓極化天線;混頻器;高增益;低雜訊;WLAN;Low Power Consumption;Triple-band circularly-polarized antenna;Mixer;High gain;Low noise|
|摘要:||本論文討論主要分為三部分，其中所提出電路之晶片製作皆由TSMC 0.18 μm mixed-signal/RF CMOS 1P6M製程來實現； 而天線部分採用厚度1.6mm的FR4板材完成。
This paper consists of three parts. All the proposed circuits were implemented in TSMC 0.18μm mixed-signal/RF CMOS 1P6M technology; and the antenna design is fabricated on an FR4 substrate. Part I, It’s a design of low noise mixer, the trans-conductance stage is implemented with low-noise amplifier cascade structure, a cross capacitance was connected between the terminal gate and source of the input stage transistor, and the input differential pair was combined together by a current source transistor, the function of this transistor is not only as a current controller but also effects the input impedance to achieve a suitable value. The trans-conductance cause the noise cancelling, in addition to this, the first stage consist of cascade architecture and it provide a high power gain to reduce the noise factor in the overall system; for switching pairs, the parasitic capacitance resulting frequency response is cancelled by an additional inductive peaking, the conversion gain versus operation frequencies will become flat; in other words, overall 3dB bandwidth will not be compressed; the following techniques gives us an excellent FOM values. According to the measurement results showed that: The S parameter are blow to -10 dB for operation frequency band 5~6GHz, and it has high conversion gain from 26.7dB to 27dB, a flat DSB noise figure 7.3~8dB, at the frequency 5.2GHz with the maximum conversion gain, the IIP3 is -12dBm, and the power consumption is 11.32mW. The FOM is 15.5 dB. Part II, the mixer design is expected to maintain a high gain and low noise. In addition, low power consumption is an important aim, with the consideration, in order create a high conversion gain but not to increase the current on the DC path, using the CG configuration as the input stage and an additional signal path is used to increase the equivalent value of trans-conductance, it implement by a negative feedback path to turn down the noise comes from gate leakage through the input parasitic capacitance path to source; to make up the low input impedance value caused by the negative feedback path, use positive feedback path to increase the input impedance value and increase the overall gain value, switch-pairs implement with PMOS transistors, instead of the traditional NMOS architecture; in this way, it can reduce the voltage headroom, and the noise source caused by the switching pairs will not leakage from parasitic to affect the trans-conductance stage. As above-mentioned improve techniques, measurement results can be obtained as the following: S parameter in the operating frequency 5 ~ 6GHz bands is below to -10dB, and it has high power gain 25dB, noise figure of 3.9 ~ 4.2dB, in the case of the highest gain IIP3 is measured as-8dBm, and the overall power consumption is reduced to 3.92mW, available FOM value increased to 23.67dB. Part III, In this proposed antenna architecture, the triple-band printed monopole antenna with triple band circular polarization is presented. The antenna generates circular polarization by two circular patches and a L shape strip. The proposed antenna can provide impedance bandwidths of 33% for 2.5GHz band, 25% for 3.5GHz band, and the 9.79% for 5.2GHz band, respectively. The axial-ratio bandwidths achieved 11.4% for 2.5GHz, 6.2% for 3.5GHz, and the 11.8% for 5.2GHz, respectively. The proposed antenna is fabricated on FR4 substrate. The operating triple frequencies cover 2.5GHz, 3.5GHz and 5.2GHz, so that the antenna could be used in WiMax and WLAN application.