This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

To acquire high efficiency and reduce electromagnetic interference in wireless high-power charging for electric vehicles (EVs), it is of great importance to realize accurate zero voltage switching angle (ZVSA) control of the inverter. However, the traditional zero-crossing detection cannot be applied in high power because of considerable noise and poor accuracy in wide power range applications. In this paper, to suppress the noise in high power, a current hysteresis comparator is adopted, and an enhanced phase detection methodology is proposed to measure the phase of resonant current by using a reference signal produced by a processor. Meanwhile, to improve the accuracy of ZVSA, a uniform time delay compensation method (UTDCM) by considering the whole time delays synthetically is proposed, and a uniform time delay equation can be obtained to guarantee the high accuracy of phase detection, especially in the wide power range. Finally, a novel control strategy with the ZVSA loop based on UTDCM is proposed for battery charging in wireless high-power transfer system. A 500-W wireless power transfer prototype is built to verify the accuracy of ZVSA based on UTDCM and the system efficiency can achieve 94.17% with $k$ = 0.22.

Analysis, Design, and Implementation of Accurate ZVS Angle Control for EV Battery Charging in Wireless High-Power Transfer

An area-efficient voltage-sensing readout circuit employing chopped voltage-controlled oscillator (VCO)-based continuous-time delta-sigma modulator (CTDSM) is presented in this paper. This VCO-based CTDSM features direct connection to sensors to eliminate pre-amplifier for achieving better hardware efficiency. The VCO is designed as a trans-conductor current-controlled oscillator, which is a fully differential $G_{m}$ stage cascaded with two CCOs, to provide a high-input impedance to sense the voltage signals from sensors. Analysis shows that the main noise and offset contributor is the $G_{m}$ stage. This problem is mitigated by employing choppers at critical location within the circuit. The VCO-based CTDSM is implemented in a 40-nm CMOS process. The power consumption is $17~\mu \text{W}$ under 1.2-V supply. With a 4-mVp (8-mV $_{\textrm {pp}})$ input, it achieves 61.85-dB signal-to-noise-and-distortion ratio over a 5-kHz bandwidth and the total harmonic distortion is −70.8 dB. The input-referred noise is 32 nV/ $\surd $ Hz. The chip area is only 0.0145 mm $^{\textrm {2}}$ .

A Low-Noise Area-Efficient Chopped VCO-Based CTDSM for Sensor Applications in 40-nm CMOS

Wireless power transmission (WPT) is a critical technology that provides an alternative for wireless power and communication with implantable medical devices (IMDs). This article provides a study concentrating on popular WPT techniques for IMDs including inductive coupling, microwave, ultrasound, and hybrid wireless power transmission (HWPT) systems. Moreover, an overview of the major works is analyzed with a comparison of the symmetric and asymmetric design elements, operating frequency, distance, efficiency, and harvested power. In general, with respect to the operating frequency, it is concluded that the ultrasound-based and inductive-based WPTs have a low operating frequency of less than 50 MHz, whereas the microwave-based WPT works at a higher frequency. Moreover, it can be seen that most of the implanted receiver’s dimension is less than 30 mm for all the WPT-based methods. Furthermore, the HWPT system has a larger receiver size compared to the other methods used. In terms of efficiency, the maximum power transfer efficiency is conducted via inductive-based WPT at 95%, compared to the achievable frequencies of 78%, 50%, and 17% for microwave-based, ultrasound-based, and hybrid WPT, respectively. In general, the inductive coupling tactic is mostly employed for transmission of energy to neuro-stimulators, and the ultrasonic method is used for deep-seated implants.

/pdf/wireless-power-transfer-approaches-for-medical-implants-a-1otgwfy743.pdf

Wireless Power Transfer Approaches for Medical Implants: A Review

Wireless power transfer has experienced a rapid growth in recent years due to the need for miniature medical devices with prolonged operation lifetime. The current implants utilize onboard batteries as their main source of power. The use of batteries is not, however, ideal because they have constrained lifetime requiring periodic replacement. Energy can be supplied to the implantable devices through wireless power transfer approaches including inductive, ultrasonic, radio frequency, and heat. The implantable devices driven by energy harvesters can operate continuously, offering ease of use and maintenance. Inductive coupling is a conventional approach for the transmission of power to implantable devices. However, the inductive coupling approach is affected by tissue absorption losses inside the human body. To power implantable devices such as neural, cochlear, and artificial heart devices, the inductive coupling approach is being used. On the other hand, ultrasonic is an emerging approach for the transmission of power to implantable devices. The enhanced efficiency and low propagation loss make ultrasonic wireless power transfer an attractive approach for use with implantable devices. This paper presents a study on the inductive and ultrasonic wireless power transfer techniques used to power implantable devices. The inductive and ultrasonic techniques are analyzed from their sizes, operating distance, power transfer efficiency, output power, and overall system efficiency standpoints. The inductive coupling approach can deliver more power with higher efficiency compared to the ultrasonic technique. On the other hand, the ultrasonic technique can transmit power to longer distances. The advantages and disadvantages of both techniques as well as the challenges to implement them are discussed.

/pdf/a-review-on-miniaturized-ultrasonic-wireless-power-transfer-48texgf8ii.pdf

A review on miniaturized ultrasonic wireless power transfer to implantable medical devices

An universal remote powering and communication system is presented for the implantable medical devices. The system be interfaced with different sensors or actuators. A mobile external unit controls the operation of the implantable chip and reads the sensor's data. A locator system is proposed to align the mobile unit with the implant unit for the efficient magnetic power transfer. The location of the implant is detected with 6 mm resolution from the rectified voltage level at the implanted side. The rectified voltage level is fedback to the mobile unit to adjust the magnetic field strength and maximize the efficiency of the remote powering system. The sensor's data are transmitted by using a free running oscillator modulated with on-off key scheme. To tolerate large data carrier drifts, a custom designed receiver is implemented for the mobile unit. The circuits have been fabricated in 0.18 um CMOS technology. The remote powering link is optimized to deliver power at 13.56 MHz. On chip voltage regulator creates 1.8 V from a 0.9 V reference voltage to supply the sensor/actuator blocks. The implantable chip dissipates 595 $\mu$ W and requires 1.48 V for start up.

/pdf/a-remotely-powered-implantable-biomedical-system-with-c5d2namtqp.pdf

A Remotely Powered Implantable Biomedical System With Location Detector

A low power SAR logic-based resistive sensor readout circuit is proposed. A high sensitivity thermistor is used for local temperature measurements. The need for a low-noise front-end voltage amplifier is avoided by employing time-domain operation. In each operation step the sensor resistance is compared with the value of a reference resistive DAC which is implemented on chip. Therefore no stable, temperature compensated reference voltage is needed for operation. Furthermore the chip is operational with supply voltages ranging from 1.2 to 1.8 volts. Detailed analyses of the circuit gain and noise are provided. In addition, the effect of circuit topology on the noise performance is discussed. The effect of 1/f noise on accuracy of the circuit is also negligible due to resetting the charge-integrating capacitor after each comparison. A prototype chip is fabricated in 0.18- μm CMOS. The circuit dissipates 15 μW with 5.5 kS/s conversion rate from a 1.5 V supply. The complete interface circuit has 14 pJ/c-s figure of merit and 7.6 effective number of bits.

A 15 $\mu{\rm W}$ 5.5 kS/s Resistive Sensor Readout Circuit with 7.6 ENOB

Multiple techniques are presented to implement an ultra-low-power remotely powered implantable system. The temperature is monitored locally by a thermistor-type sensor. The resistive response of the sensor is amplified and resolved in the time-domain. The data is transmitted using a duty cycled free running oscillator operating at 868 MHz. In addition, the sensor interface and data transmitter are time interleaved to improve power link sensitivity. A prototype chip is fabricated in 0.18 μm CMOS. The implant is powered with a 13.56 MHz inductive link and operates with a minimum power of 53 μW. The system is capable of recording temperature with accuracy of ±0.09 °C when 8 times oversampling is done at the base station.

A remotely powered implantable IC for recording mouse local temperature with ±0.09 °C accuracy

An implantable system for monitoring vital parameters via bio-sensors inside freely moving laboratory animals and its powering system are presented. The required 2 mW are harvested by the magnetic coupling with an external coil placed under the living space of the animal. The servo X - Y rails move the external coil and track the animal. Dynamic power-adaptation keeps the harvested power level constant against misalignments of transmitting coil and moving animal. Entire system and basic blocks integrated using a 0.18 urn CMOS technology are presented. Experimental results show the effectiveness of the powering system.

/pdf/short-range-remote-powering-of-implanted-electronics-for-35232efuvy.pdf

Short range remote powering of implanted electronics for freely moving animals

A charge integrator is an essential building block used in time-based ADCs and sensor readout circuits. In this paper, time-domain noise analysis is used to calculate the effect of all noise sources, including 1/f noise, on the voltage noise variance of the integrator. The results show that for short charge integration intervals, the contribution of 1/f noise sources to the total voltage variance of the integrator is not significant. Different design trade-offs for optimally choosing the capacitance of the integrator and current mirror ratio are discussed. The accuracy of the developed equations is verified by transient noise simulations.

Mehrdad A. Ghanad

Papers

A Remotely Powered Implantable Biomedical System With Location Detector

A 15 $\mu{\rm W}$ 5.5 kS/s Resistive Sensor Readout Circuit with 7.6 ENOB

A remotely powered implantable IC for recording mouse local temperature with ±0.09 °C accuracy

Short range remote powering of implanted electronics for freely moving animals

Noise analysis for time-domain circuits