Research On Key Technologies Of On-chip Reconfigurable Filters Based On GaAs Process

With the diversification of modern wireless communication system standards,its degree of intelligence is increasing day by day.The traditional transceiver front-end uses switching filter banks to distinguish different working frequency bands and working modes,but it costs system’s size,complex structure and higher power consumption.As the key to the realization of intelligent systems,reconfigurable technology uses tunable components to control the passive network,so that the front-end of the transceiver can be reconfigured to achieve versatility.The filter plays a key role in the RF transceiver system,and its performance determines whether the subsequent amplification,frequency mixing and signal processing circuits can work in a predetermined mode.Therefore,the research on reconfigurability of filters has become a hot problem at present.Limited by the performance of the reconfigurable filter,in order to better meet the requirements of 2～18GHz radar electronic countermeasure applications,the switching filter bank also has important research significance.This article explores the on-chip reconfigurable filter based on WIN 0.15um GaAs technology,and designs a filter bank for 2～18GHz and a single-pole multi-throw switch for the traditional filter bank.Its main work includes:1.Using "back-to-back" capacitors and switched capacitor arrays as tuning elements,under the working voltage of-5V～+5V,three reconfigurable frequency bandpass filters with a fixed bandwidth of 800MHz are realized,and their frequency adjustment ranges cover respectively:（1）1.9～3.2GHz,（2）2.72～3.50 GHz,（3）3.88～5.29GHz.The S21 is bigger than-4.2dB,the out-of-band suppression of 30%deviation from the sideband is greater than 25dB,the insertion loss variation is less than 1dB,and the in-band flatness is less than 0.5dB.At the same time,a bandwidth reconfigurable bandpass filter with bandwidth adjustment range of 330 to 750MHz and center frequency fixed at 1.8GHz is implemented.The S21 is bigger than-6.86dB,the 35%off-band suppression is greater than 28.6dB,the insertion loss variation is less than 2dB,and the in-band flatness is less than 1dB.Both filters have been taped out and the results analyzed.2.Designed 5 types of band-pass filters for the filter banks used in electronic countermeasures,and its frequency bands are:（1）1.9～3.2GHz,（2）2.2～3.7GHz,（3）2.7～4.6GHz,（4）3.6～6.1GHz,（5）5.1～8.9GHz.The filter is an LC lumped filter with an elliptic function prototype,and its S21 is better than-3dB,and the bandstop suppression is greater than 40dB.3.Using the traditional series structure and series-parallel structure,two single-pole multi-throw switches are designed for 2～18GHz,which are a symmetrical SP8T switch,an asymmetrical SP7T switch and a SPDT switch.The main work includes the principle analysis of pHEMT switch tube,the selection of MOS tube,the simulation design of schematic diagram and layout,and the design requirements of S21 is bigger than-2.3dB,isolation between ports greater than 20dB,and return loss better than 15dB are realized in the whole frequency band.