A Study on RF Receiver Design for Ultra-Low Power and Carrier Aggregation Applications

Abstract

Firstly, an ultra-low-power fully integrated wide band receiver for WSN using passive mixer-first structure is implemented. The design target of the receiver is ultra-low-power operation with wide band coverage. Fabricated in 28-nm CMOS process, the receiver employs a passive mixer-first RF front-end with zero-IF architecture which is driven by non-overlapping 4-phase local oscillator (LO). To minimize power consumption in LO driving stage which consumes the largest portion of power in this structure, supply voltage and device size optimization techniques are introduced. Enhanced non-overlapping LO circuit is proposed to prevent degradation of the noise figure. The receiver also includes a low power base band amplifier and in-band noise reduced biquad filter. The total receiver chain achieves conversion gain of 55 dB, noise figure of 13.6 dB and IIP3 of -7.5 dBm (@ 10 MHz spacing) with power consumption under 1 mW at the frequency band of 0.85 ~2.55 GHz.

Secondly, a 2.4 GHz ISM band ultra-low-power receiver with a passive Sliding-IF (SIF) mixer structure is implemented. A self-biased inverter-based LNA which has high FOM and good linearity in low power operation is employed. All passive SIF mixer is proposed to avoid power consumption in an active mixer and high frequency operation of a non-overlapping 4-phase generator. The passive SIF mixer is analyzed for optimal operation and proper inter-stage matching. A dual mode Programmable Gain Amplifier (PGA) based on Shallen-key LPF is proposed to enhance gain control range. The proposed PGA has gain range of 55 dB with power consumption of 120 uW. The overall receiver has 15 ~ 70 dB gain, 6.5 dB NF, -10 dBm IIP3 (@ 3 MHz tone spacing), and consumes 640 uW at 2.45 GHz input frequency.

The other part of this dissertation is reconfigurable 4 channel carrier aggregation receiver using harmonic recombination technique. Reconfigurable 4-band carrier aggregation receiver using only one frequency source is implemented. The receiver targets not only for intra-band but also for inter-band carrier aggregation by employing an harmonic recombination technique. By using an 8-phase mixer for an harmonic recombination, the 1st and 3rd order bands can be used for an inter-band carrier aggregation. Using 28-nm CMOS process, an wide-band high performance LNA [5] is designed and an 8-phase differential mixer is designed with a non-overlapping LO generator. The harmonic recombination stage is implemented with a base band poly phase filter and an active RC complex Band Pass Filter (BPF). The receiver covers the input frequency range of 0.5 GHz~3.6 GHz with the 3.7 dB NF and 65 dB voltage gain. The center frequency of one band can be tuned anywhere between 1 ~ 50 MHz. The receiver also rejects opposite channel by 45 dB and the 3rd order channel by 30 dB.