cmos 2.4 GHz harmonic reject mixers for wideband transceivers.

摘要

In this work the harmonic reject topology conventionally used only for low frequency wide band applications like TV, is implemented for higher frequencies in the GHz range. This work presents the system analysis, design implementation and probe measurement of a wide band harmonic reject transceiver system including a harmonic reject mixer (HRM) and tuned amplifiers. The design is implemented in IBM 0.18mum Complementary Metal-Oxide Semiconductor (CMOS) technology. The receiver achieves an overall third harmonic rejection of greater than 55dB in the 2.4 GHz industrial, scientific and medical (ISM) radio band. The receiver is implemented for an intermediate frequency (IF) of 600MHz. It is a direct conversion implementation and requires a local oscillator (LO) operating at 1.9GHz. The work also includes design of a high frequency divideby4 circuit operating at 7.6GHz to generate the three phases (0° , 45° and 90° ) of 1.9 GHz required to drive the HRM.;The concept of harmonic mixing is also extended to design a harmonic reject heterodyne transmitter to reduce the need of IF filters and to reduce the linearity requirements of power amplifier employed in transmitters thus improving the efficiency of the transmitter system. The challenges include addressing the mismatch limitations of HRM mixers at high frequencies and generating well balanced LO lines with close to perfect relative phase difference necessary for successful implementation of the HRM. Further challenges include addressing the design constraints of high frequency dividers, radio frequency (RF) filters with moderate gain, low noise figure and matched for wide band.;This implementation is especially important for military applications such as communication system in submarines and civilian applications in the 2.4 GHz ISM band where the harmonics are adversely affected by satellite communication. Most of the present day high frequency harmonic reject receivers either employ external filters to achieve sufficient suppression of blockers at third harmonics or are able to achieve harmonic rejection in very low magnitude (≤ 40dB). This is especially true for frequencies in GHz range. This work eliminates the need of external filters while achieving high harmonic rejection with low power consumption.