Nano-metric optimised CMOS RF receiver front-end components for UHF RFID readers : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Auckland, New Zealand

Abstract

As the capabilities of wireless hand-held devices continue to increase, more pressure is placed on the performance of RF transceiver front-ends. The primary objective of this research is to investigate optimal methods of implementing a receiver front-end with reduced power dissipation, reduced design complexity and minimised cost. This design will be implemented on CMOS technology due to its advantages in system integration and low-cost mass production. This thesis presents the optimisation of a CMOS RF receiver front-end components design for 866 MHz UHF RFID readers. The completed receiver front-end was fabricated on an IBM 130nm CMOS process. Circuit-level techniques were employed to reduce chip size and power consumption while providing enhanced performance. The inclusion of the finite drain-source conductance 𝑔𝑑𝑠 effect improves the nano-metric design optimisation algorithm. Simulated results and experimental data are presented that demonstrate the RF receiver design with low power dissipation and low noise while providing high performance. Low-noise amplifiers using a power-constrained simultaneous noise and input matching (PCSNIM) technique are presented first. In contrast to previously published narrow-band LNA designs, the proposed design methodology includes the finite drain-source conductance of devices, thus achieving simultaneous impedance and minimum noise matching at the very low power drain of 1.6mW from a 1V supply. The LNA delivers a power gain (S21) of 17dB, a reverse isolation (S12) of -34dB and an input power reflection (S11@866 MHz) of -30dB. It has a minimum pass-band NF of around 2dB and a 3rd order input referred intercept point (IIP3) of -16dBm. A low noise mixer is also presented utilising the PCSNIM topology with current bleeding techniques. This design is proposed to replace the conventional Gilbert cell mixer that usually exhibits a high noise figure. The proposed mixer has demonstrated the ability to scale to the targeted 130nm process and meets design requirement at the required operating frequency. It has a power conversion gain of 14.5dB, DSB noise figure of 8.7dB DSB and an IIP3 of -5.1dBM. The mixer core itself only consumes 6mW from a 1.2V supply and the complete test circuit consumes 10mW with a balun at each port. Finally, a voltage controlled oscillator (VCO) is presented. A quadrature VCO (QVCO) structure is selected to overcome the image rejection issue. Since the main goal for this work is to design a low power receiver front-end, a folded-cascode topology is employed to enable the QVCO to operate under 1V power supply. The proposed VCO has a phase noise of -140dBc/Hz at 3-MHz offset from the carrier with only 5mW of power dissipation. This gives a FoM value of -181dBc/Hz that compares favourably to recently published designs.