2.4 GHz CMOS Power Amplifier with Mode-Locking Structure to Enhance Gain

We propose a mode-locking method optimized for the cascode structure of an RF CMOS power amplifier. To maximize the advantage of the typical mode-locking method in the cascode structure, the input of the cross-coupled transistor is modified from that of a typical mode-locking structure. To prove the feasibility of the proposed structure, we designed a 2.4 GHz CMOS power amplifier with a 0.18 μm RFCMOS process for polar transmitter applications. The measured power added efficiency is 34.9%, while the saturated output power is 23.32 dBm. The designed chip size is 1.4×0.6 mm2

Recent Developments in Automatic Impedance Matching and Antenna Tuning for Wireless and Mobile Communications

This paper reviews recent developments in automatic impedance matching and antenna tuning for wireless and mobile communications.Peer reviewe

A fully integrated low-power SiGe power amplifier for biomedical applications

In this work, a full-integrated very-low power SiGe Power Amplifier (PA) is realized using the IHP (Innovations for High Performance), 0.25μm-SiGe process. The behaviour of the amplifiers has been optimized for the 2.1-2.4 GHz frequency band for a higher 1-dB compression point and high efficiency at a lower supply voltage. The PA delivers an output power of 3.75 mW and 1.25 mW for 2V and 1V, respectively. The PA measurements yielded the following parameters; gain of 13 dB, 1-dB compression point of 5.7 dBm, and Power-Added-Efficiency of 30% for 2V supply voltage. The PA circuit can go down to 1V of supply voltage with a gain of 10 dB, 1-dB compression point of 1 dBm, and Power-Added-Efficiency of 20%. For both supply voltages, the input and the output of the circuit give good reflection performance. With this performance, the PA circuit may be used for low-power biomedical implanted transceiver systems

Fully integrated low-power SiGe power amplifier for biomedical applications

A full-integrated very low-power SiGe power amplifier (PA) is realised using the innovations for high performance, 0.25 mu m SiGe process. The behaviour of the amplifiers has been optimised for the 2.1-2.4 GHz frequency band for a higher 1 dB compression point and high efficiency at a lower supply voltage. The PA delivers an output power of 3.75 and 1.25 mW for 2 and 1 V, respectively. The PA measurements yielded the following parameters: gain of 13 dB, 1 dB compression point of 5.7 dBm, and power added efficiency of 30% for 2 V supply voltage. The PA circuit can go down to 1 V of supply voltage with a gain of 10 dB, 1 dB compression point of 1 dBm, and power added efficiency of 20%. For both supply voltages, the input and the output of the circuit give good reflection performance. With this performance, the PA circuit may be used for low-power biomedical implanted transceiver systems

A delay spread cancelling waveform characterizer for RF power amplifiers

A two channel 65 nm CMOS RF-waveform characterizer is presented that enables multi-harmonic Adaptive Matching Networks (AMN) or Adaptive Digital Pre-Distortion (ADPD) in RF-power amplifiers. The characterizer measures the DC component and the first 3 harmonics of RF signals by applying a DFT to 8 (ideally) equally spaced quasi-DC output voltages. Conventionally in these types of systems accuracy is limited by sample timing accuracies, which in our case are mainly due to delay cell mismatch. We introduce a novel way to cancel delay cell mismatch, that significantly increases measurement accuracy at the cost of only a small power and area increase. The RF-waveform characterizer achieves 6.8-bit measurement linearity together with a (clock feedthrough limited) 24 dB SFDR. The measured power consumption for our proof-of-principle demonstrator is 18.6 mW at a maximum input signal frequency of 1.1 GHz under continuous operation

Achieving Longevity in Wireless Body Area Network by Efficient Transmission Power Control for IoMT Applications

The application of tiny body sensors to collect, process, store, analyze, and retrieve medical information from a human body is a part of the Internet of Medical Things (IoMT).  IoMT helps to monitor and track human vital health parameters, predict disease, notify the patients and the health care professionals with relevant data for analyzing the problems before they become severe and for earlier invention. By 2022, more than 60 % of IoT applications will be health-related. The convergence of biomedical sensors, wireless body area networks (WBAN), Information technology, and bioinformatics will help improve the efficiency of saving human lives. In a WBAN, network longevity is challenging because of the limited supply of low power battery energy in tiny body sensor nodes. Here, we proposed an energy-efficient transmission power control (TPC) algorithm to extend the network lifetime in IoMT networks for healthcare applications by eliminating the transceiver overhearing problem. In TPC, human tissue resistivity properties are considered to adjust the transmission power, which reduces the communication power and extends the network lifetime. The simulation results show that network power consumption is reduced by 35%

An innovative and simpleiImpedance matching network using stacks of metasurface sheets to suppress the mismatch between antennas and RF front-end transceivers circuits

A innovative and simple impedance matching network is presented that is implemented by stacking together metasurface (MTS) sheets. The technique is shown to reduce the mismatch between free-space and RF front-end antenna of a receiver. The MTS based impedance matching network is modeled as a transmission-line loaded with shunt and series capacitances and inductances, respectively. The proposed MTS impedance matching network can be employed to effectively interface the free-space to the antenna of an RF receiver and thereby optimize power absorption. Each MTS impedance matching sheet comprises two-dimensional periodic array of subwavelength microstrip resonator unit-cells that are spaced at a wavelength that is smaller than the frequency of operation. The unit-cells are square shaped patches and embedded with cross-shaped slots that are grounded through a via-hole. The MTS impedance matching network was fabricated using FR-4 substrate. 3D full-wave EM tool by Ansys HFSS™ was used to verify its effectiveness. The proposed MTS impedance matching sheet is relatively easy to implement in practice

Optimum power transfer in RF front end systems using adaptive impedance matching technique

Matching the antenna's impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna's radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (<5 s) and is highly accurate for autonomous adaptive antenna matching networks

Optimum Power Transfer in RF Front End Systems Using Adaptive Impedance Matching Technique

Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence