Research And Design For Intermediate Frequency Complex Filter In High Linearity Receiver

Satellite navigation industry not only accompanied by huge economic interests,but also related to the homeland security and public safety of a country.The Chinese beidou navigation system develops steadily recent years.The high linearity receiver becomes popular for the high power of the human interference signal.In this research,a baseband intermediate frequency complex filter applied in high linearity beidou navigation receiver is proposed.The basic principles of the filter are firstly introduced.Further,the method that reject the image signal by using complex filter is proposed.Comparing different structures,we choose the 6^th order active-RC chebyshev complex filter as our final scheme.A current-reusing,feedforward compensation?FFC?OTA is designed to consist the integrator.The linearity of the complex filter can be significantly improved by 7dB compared to the traditional miller compensation scheme.The non-ideality compensation for the integrator is also introduced in this paper.The calibration method for the value variation of the resistor and capacitor through the process and temperature variation is proposed.The complex filter is centered at 15.48MHz with a bandwidth of 20.46MHz using the TSMC 180nm process.The in-band ripple is less than 1dB and the gain tuning range is from-20dB to 11dB.The out-band rejection at 1.5 times BW is about 35dB.It can achieve more than+28dBm IIP3 through the pass band and a maximum IIP3 of+40dBm.Image rejection ratio is 43dB.It consumes 22mA at the 3.3v supply.