Low-power CMOS front-ends for wireless personal area networks

The potential of implementing subthreshold radio frequency circuits in deep sub-micron CMOS technology was investigated for developing low-power front-ends for wireless personal area network (WPAN) applications. It was found that the higher transconductance to bias current ratio in weak inversion could be exploited in developing low-power wireless front-ends, if circuit techniques are employed to mitigate the higher device noise in subthreshold region. The first fully integrated subthreshold low noise amplifier was demonstrated in the GHz frequency range requiring only 260 μW of power consumption. Novel subthreshold variable gain stages and down-conversion mixers were developed. A 2.4 GHz receiver, consuming 540 μW of power, was implemented using a new subthreshold mixer by replacing the conventional active low noise amplifier by a series-resonant passive network that provides both input matching and voltage amplification. The first fully monolithic subthreshold CMOS receiver was also implemented with integrated subthreshold quadrature LO (Local Oscillator) chain for 2.4 GHz WPAN applications. Subthreshold operation, passive voltage amplification, and various low-power circuit techniques such as current reuse, stacking, and differential cross coupling were combined to lower the total power consumption to 2.6 mW. Extremely compact resistive feedback CMOS low noise amplifiers were presented as a cost-effective alternative to narrow band LNAs using high-Q inductors. Techniques to improve linearity and reduce power consumption were presented. The combination of high linearity, low noise figure, high broadband gain, extremely small die area and low power consumption made the proposed LNA architecture a compelling choice for many wireless applications.Ph.D.Committee Chair: Laskar, Joy; Committee Member: Chakraborty, Sudipto; Committee Member: Chang, Jae Joon; Committee Member: Divan, Deepakraj; Committee Member: Kornegay, Kevin; Committee Member: Tentzeris, Emmanoui

A CMOS low pass filter for soc lock-in-based measurement devices

This paper presents a fully integrated Gm–C low pass ¿lter (LPF) based on a current ¿steering Gm reduction-tuning technique, specifically designed to operate as the output stage of a SoC lock-in amplifier. To validate this proposal, a first-order and a second-order single-ended topology were integrated into a 1.8 V to 0.18 µm CMOS (Complementary Metal-Oxide-Semiconductor) process, showing experimentally a tuneable cutoff frequency that spanned five orders of magnitude, from tens of mHz to kHz, with a constant current consumption (below 3 µA/pole), compact size (<0.0140 mm2 /pole), and a dynamic range better than 70 dB. Compared to state-of-the-art solutions, the proposed approach exhibited very competitive performances while simultaneously fully satisfying the demanding requirements of on-chip portable measurement systems in terms of highly efficient area and power. This is of special relevance, taking into account the current trend towards multichannel instruments to process sensor arrays, as the total area and power consumption will be proportional to the number of channels

A 2.5 GHz Optoelectronic Amplifier in 0.18 m CMOS

The ever-growing need for high speed data transmission is driven by multimedia and telecommunication demands. Traditional metallic media, such as copper coaxial cable, prove to be a limiting factor for high speed communications. Fiber optic methods provide a feasible solution that lacks the limitations of metallic mediums, including low bandwidth, cross talk caused by magnetic induction, and susceptibility to static and RF interferences. The first scientists to work with fibers optics started in 1970. One of the early challenges they faced was to produce glass fiber that was pure enough to be equal in performance with copper based media. Since then, the technology has advanced tremendously in terms of performance, quality, and consistency. The advancement of fiber optic communication has met its limits, not in the purity of its fiber media used to guide the data-modulated light wave, but in the conversion back and forth between electric signals to light. A high speed optic receiver must be used to convert the incident light into electrical signals. This thesis describes the design of a 2.5 GHz Optoelectronic Amplifier, the front end of an optic receiver. The discussion includes a survey of feasible topologies and an assessment of circuit techniques to enhance performance. The amplifier was designed and realized in a TSMC 0.18 µm CMOS process

Microwave and Millimeter-wave Concurrent Multiband Low-Noise Amplifiers and Receiver Front-end in SiGe BiCMOS Technology

A fully integrated SiGe BiCMOS concurrent multiband receiver front-end and its building blocks including multiband low-noise amplifiers (LNAs), single-to-differential amplifiers and mixer are presented for various Ku-/K-/Ka-band applications. The proposed concurrent multiband receiver building blocks and receiver front-end achieve the best stopband rejection performances as compared to the existing multiband LNAs and receivers. First, a novel feedback tri-band load composed of two inductor feedback notch filters is proposed to overcome the low Q-factor of integrated passive inductors, and hence it provides superior stopband rejection ratio (SRR). A new 13.5/24/35-GHz concurrent tri-band LNA implementing the feedback tri-band load is presented. The developed tri-band LNA is the first concurrent tri-band LNA operating up to millimeter-wave region. By expanding the operating principle of the feedback tri-band load, a 21.5/36.5-GHz concurrent dual-band LNA with an inductor feedback dual-band load and another 23/36-GHz concurrent dual-band LNA with a new transformer feedback dual-band load are also presented. The latter provides more degrees of freedom for the creation of the stopband and passbands as compared to the former. A 22/36-GHz concurrent dual-band single-to-differential LNA employing a novel single-to-differential transformer feedback dual-band load is presented. The developed LNA is the first true concurrent dual-band single-to-differential amplifier. A novel 24.5/36.5 GHz concurrent dual-band merged single-to-differential LNA and mixer implementing the proposed single-to-differential transformer feedback dual-band load is also presented. With a 21-GHz LO signal, the down-converted dual IF bands are located at 3.5/15.5 GHz for two passband signals at 24.5/36.5 GHz, respectively. The proposed merged LNA and mixer is the first fully integrated concurrent dual-band mixer operating up to millimeter-wave frequencies without using any switching mechanism. Finally, a 24.5/36.5-GHz concurrent dual-band receiver front-end is proposed. It consists of the developed concurrent dual-band LNA using the single-to-single transformer feedback dual-band load and the developed concurrent dual-band merged LNA and mixer employing the single-to-differential transformer feedback dual-band load. The developed concurrent dual-band receiver front-end achieves the highest gain and the best NF performances with the largest SRRs, while operating at highest frequencies up to millimeter-wave region, among the concurrent dual-band receivers reported to date

Microwave and Millimeter-wave Concurrent Multiband Low-Noise Amplifiers and Receiver Front-end in SiGe BiCMOS Technology

A fully integrated SiGe BiCMOS concurrent multiband receiver front-end and its building blocks including multiband low-noise amplifiers (LNAs), single-to-differential amplifiers and mixer are presented for various Ku-/K-/Ka-band applications. The proposed concurrent multiband receiver building blocks and receiver front-end achieve the best stopband rejection performances as compared to the existing multiband LNAs and receivers. First, a novel feedback tri-band load composed of two inductor feedback notch filters is proposed to overcome the low Q-factor of integrated passive inductors, and hence it provides superior stopband rejection ratio (SRR). A new 13.5/24/35-GHz concurrent tri-band LNA implementing the feedback tri-band load is presented. The developed tri-band LNA is the first concurrent tri-band LNA operating up to millimeter-wave region. By expanding the operating principle of the feedback tri-band load, a 21.5/36.5-GHz concurrent dual-band LNA with an inductor feedback dual-band load and another 23/36-GHz concurrent dual-band LNA with a new transformer feedback dual-band load are also presented. The latter provides more degrees of freedom for the creation of the stopband and passbands as compared to the former. A 22/36-GHz concurrent dual-band single-to-differential LNA employing a novel single-to-differential transformer feedback dual-band load is presented. The developed LNA is the first true concurrent dual-band single-to-differential amplifier. A novel 24.5/36.5 GHz concurrent dual-band merged single-to-differential LNA and mixer implementing the proposed single-to-differential transformer feedback dual-band load is also presented. With a 21-GHz LO signal, the down-converted dual IF bands are located at 3.5/15.5 GHz for two passband signals at 24.5/36.5 GHz, respectively. The proposed merged LNA and mixer is the first fully integrated concurrent dual-band mixer operating up to millimeter-wave frequencies without using any switching mechanism. Finally, a 24.5/36.5-GHz concurrent dual-band receiver front-end is proposed. It consists of the developed concurrent dual-band LNA using the single-to-single transformer feedback dual-band load and the developed concurrent dual-band merged LNA and mixer employing the single-to-differential transformer feedback dual-band load. The developed concurrent dual-band receiver front-end achieves the highest gain and the best NF performances with the largest SRRs, while operating at highest frequencies up to millimeter-wave region, among the concurrent dual-band receivers reported to date

Low-Power Wireless Medical Systems and Circuits for Invasive and Non-Invasive Applications

Approximately 75% of the health care yearly budget of public health systems around the world is spent on the treatment of patients with chronic diseases. This, along with advances on the medical and technological fields has given rise to the use of preventive medicine, resulting on a high demand of wireless medical systems (WMS) for patient monitoring and drug safety research. In this dissertation, the main design challenges and solutions for designing a WMS are addressed from system-level, using off-the-shell components, to circuit implementation. Two low-power oriented WMS aiming to monitor blood pressure of small laboratory animals (implantable) and cardiac-activity (12-lead electrocardiogram) of patients with chronic diseases (wearable) are presented. A power consumption vs. lifetime analysis to estimate the monitoring unit lifetime for each application is included. For the invasive/non-invasive WMS, in-vitro test benches are used to verify their functionality showing successful communication up to 2.1 m/35 m with the monitoring unit consuming 0.572 mA/33 mA from a 3 V/4.5 V power supply, allowing a two-year/ 88-hour lifetime in periodic/continuous operation. This results in an improvement of more than 50% compared with the lifetime commercial products. Additionally, this dissertation proposes transistor-level implementations of an ultra-low-noise/low-power biopotential amplifier and the baseband section of a wireless receiver, consisting of a channel selection filter (CSF) and a variable gain amplifier (VGA). The proposed biopotential amplifier is intended for electrocardiogram (ECG)/ electroencephalogram (EEG)/ electromyogram (EMG) monitoring applications and its architecture was designed focused on improving its noise/power efficiency. It was implemented using the ON-SEMI 0.5 µm standard process with an effective area of 360 µm2. Experimental results show a pass-band gain of 40.2 dB (240 mHz - 170 Hz), input referred noise of 0.47 Vrms, minimum CMRR of 84.3 dBm, NEF of 1.88 and a power dissipation of 3.5 µW. The CSF was implemented using an active-RC 4th order inverse-chebyshev topology. The VGA provides 30 gain steps and includes a DC-cancellation loop to avoid saturation on the sub-sequent analog-to-digital converter block. Measurement results show a power consumption of 18.75 mW, IIP3 of 27.1 dBm, channel rejection better than 50 dB, gain variation of 0-60dB, cut-off frequency tuning of 1.1-2.29 MHz and noise figure of 33.25 dB. The circuit was implemented in the standard IBM 0.18 µm CMOS process with a total area of 1.45 x 1.4 mm^(2). The presented WMS can integrate the proposed biopotential amplifier and baseband section with small modifications depending on the target signal while using the low-power-oriented algorithm to obtain further power optimization