The Linc Zero If Modulator Front-end Development

This project is part of the National Hi-Tech Research and Development Program (863). For higher efficiency and high linear application, this research deals with problems exist in zero-IF modulation of wide-band, high-efficiency linear transmitter. LINC(Linear Amplification With Nonlinear Components)transmitter technology is one of this kind. It uses nonlinear component to amplify constant envelop signal, and then change them into initial signal through power Combiner.Zero-IF modulation system is design and improved in this project to meet the requirement of LINC zero-IF transmitter. The modulate system design and the feasibility of LINC transmitter have been proved by test result.Task completed in this subject:1,Zero-IF structure is confirmed according to the requirement of LINC transmitter. Modulate system scheme is adapted to meet the demand of amplitude and phase imbalance.2,Simulate LINC transmitter modulate system, confirm the type and design target of difference-low-pass filter and directional coupler, accomplish design and debug of this two circuits.3,Confirm design target of local signal source in system simulation; analyze the effect of EVM brought by phase noise. Confirm the scheme of mixed charge pump Phase-locked loops.4,Analyze the theory of quadrature modulator, methods of restraining local oscillator leakage and side-band leakage. Adapt suitable modulation scheme to develop modulate preciseness; design and debug the system.