In recent years, the wireless communication systems have been changing rapidly. In order to realize the
portable electric devices, the miniaturization, light weight and low cost of the devices are very important issues,
and longer life of the battery is also desired. The implementation of RF analog circuits and the baseband
digital circuits in the same chip by using CMOS technology leads to the capability of reducing the size, weight,
cost and power. However, the implementation is very difficult because RF CMOS circuit technology cannot be
established.
In this paper, the optimal design to improve the conversion gain of the even-harmonic mixer used in the direct
conversion receivers is proposed. The RF signal input terminal of MOSFET's transconductance parameter(K)
is not changed in consideration of the influence of parasitic capacitance in the imput terminal, but the LO
signal input terminal is changed. Under these conditions, the optimal value could be derived. The proposed
circuit that used the optimal value was evaluated by using HSPICE-RF. The results show that the operation
of the circuit as an even-harmonic mixer is confirmed. Furthermore, the conversion gain to the baseband of the
proposed circuit can be improved by 4 dB as deriving the theory. The circuit using the optimal value is very
useful for high- gain even-harmonic mixers.
雑誌名
Memoirs of the Faculty of Engineering, Miyazaki University