Design And Implementation Of IF Module For C-Band RF Transceiver

With rapid development of active electronically scanned array (AESA) technology, the requirement of RF front-end in active phased array transceiver systems is higher and higher. As a technology solution to the next generation of highly integrated, multi-functional and cost-effective transceiver front-end, multi-function chip (MFC) is widely adopted in industry and military. MFC RF transceiver front-end refers to an integrated MMIC containing all the functions, like phase shift, attenuation, amplification, originally done by multiple MMICs. The development of microelectronics technology, especially in CMOS, makes it possible for the realization of highly integrated, low-cost multi-function phased array chip.This paper presents the circuit design of IF module for C-band transceiver in 0.18μm RF CMOS technology. At first, it introduces the overall structure of the IF module and the basic theory of VGA, PA and balun. IF module in receiving link contains an active two-stage differential to single-end balun (D2S balun) and an IF driver amplifier with CSCG structure biased in class AB for better linearity and output match. The first stage of D2S balun converts the differential voltage signal into in-phase voltage signal and the second stage achieves the summation of in-phase voltage signal in current region. IF module in transmitting link contain a single-end to differential balun with cross-coupling capacitor and an open-loop VGA with variable transconducrance. The on-chip test results show 2.01dB voltage gain,8.5dBm output 1dB compression point, less than -15dB S22 at working frequency of 1.3～1.4GHz, less than 1dB band fluctuation while drawing about 30mA from a 3.3V supply in receiving state. It shows -2dBm input 1dB compression point, less than 1dB band fluctuation, less than -15dB S22 at working frequency of 1.3～1.4GHz while drawing about 30mA from a 3.3V supply in transmitting state.The design has the advantages of well match, high linearity, one port receiving and transmitting signal, etc. The chip shows a stable performance and can be used in C-band RF transceiver chip.