The MMIC Research On Amplitude Variable And Modulator Circuit

Under the urgent need of high mobility,high speed,and miniaturization of modern communication systems,research on high-performance microwave RF communication components has become a major research direction.The emergence of various emerging technologies has made the application of technology in the engineering field more and more extensive.The required working frequency band has become wider and wider.In addition,communication spectrum resources have become more and more intensive,so traditional narrowband systems can no longer meet the needs of these technologies.In order to achieve higher transmission rates,more miniaturized systems,the performance and size of microwave/millimeter-wave amplitude variable MMIC circuits and microwave/millimeter-wave modulator MMIC circuits play an important role in the communication link.The amplitude variable circuit determines whether the received signal can be accurately transmitted to the information processing terminal,the modulator circuit determines whether the baseband information can be accurately modulated on the carrier,i.e.reducing the bit error rate to improve the communication quality and communication rate.Commonly used microwave/millimeter-wave amplitude variable circuits are classified into two types,i.e.attenuation circuits and variable gain amplifier circuits.The former has a simple circuit structure but can only provide amplitude attenuation while the latter circuit is slightly more complicated,but it can both increase the amplitude and reduce the amplitude.In comparison,the variable gain amplifier circuit is based on the actual engineering needs.The commonly used microwave/millimeter-wave modulator circuit can be classified according to different functions.However,in the millimeter wave frequency,it also takes into account the circuit size and performance,direct vector modulation technology has always been a research hotspot and widely used.Compared with the traditional modulator circuit,the direct vector modulation technology reduces the intermediate frequency modulation process,which reduces the cost and improves the reliability of the system.Therefore,based on current research hotspots and practical engineering needs,a 50 MHz to 8 GHz wideband digital variable gain amplifier is designed by using 0.15 ?m GaAs E-Mode pHEMT process.By adopting the divider circuit using series resistor,a architecture based on modified the stable gain amplifier with cascaded attenuator is introduced to achieve a variable gain from 2 dB to 33.5 dB with a minimum gain step of 0.5 dB,a maximum gain variation error of 1 dB and a noise performance of less than 4 dB.The proposed design achieves the chip size of only 2.4 mm × 1.1 mm.It achieves the area reduction by 25% as compared with that of the conventional structure chips.Under the same process,a 40 GHz-75 GHz wideband vector modulator is designed.The design of the broadside coupler is designed by using two bending metal layer coupled structure.The advantage is that under wide-band response the double-layer structure is used to reduce the overall circuit area significantly.The circuit achieves a maximum amplitude imbalance of ±1 dB,a phase imbalance of up to ±3°,and an insertion loss of 12.5 dB.The chip size is 2.3 mm × 1.7 mm.In summary,the microwave/millimeter-wave amplitude variable and modulator MMIC circuit designed in this paper has the characteristics of wide band,compact circuit structure and excellent performance.