IMPLEMENTATION OF GILBERT CELL MIXER FOR RF RECEIVER

Abstract

Abstract This thesis focuses on the designing and implementation of radio-frequency CMOS down-conversion mixers for wireless applications. The Gilbert cell has been used as the basic configuration for all mixers. The thesis involves the comparison of performance parameters for double balanced down-conversion mixers using various loads. Two techniques, source degeneration and current bleeding for enhancing the linearity of the mixers are implemented and their effects on mixer performance are observed. The simulations are performed with 1.8 V voltage supply using 180 nm CMOS process. The RF power used is -30 dBm and LO power is set to 5 dBm. A new Ultra Low Power Diode (ULPD) load based down-conversion mixer is also designed and simulated. It is designed to operate at 2.5 GHz RF frequency with 250 MHz Intermediate frequency. The conversion gain provided by the mixer is maximum ~8dB at 2.1GHz RF frequency. The power consumption for the mixer core circuit is ~17mW. The mixer presents good RF to IF port isolation with input return loss less than zero. The Input Third Order Intercept point (IIP3) increases from ~ 9dBm to 15.8 dBm for variation of the source degeneration inductors from 1 nH to 20 nH. The IIP3 obtained is 11.64 dBm at 4 GHz RF frequency with 1nH inductor.