Impulse-radio Ultra-wideband Transmitter Research Articles

High data rate and energy efficient configurable IR-UWB transmitter with an integrated balun

This paper presents a novel, digitally configurable, switching oscillator-based impulse radio ultra-wideband (IR-UWB) transmitter that is robust to process variations. The pulse width and pulse position properties of the output waveform are configurable to ensure operation for the desired bandwidth and output pulse energy values. The architecture is based on a cross-coupled LC voltage-controlled oscillator (LC VCO) implemented with a custom-designed on-chip balun at a center frequency of 2.4 GHz. With the usage of this on-chip balun, the need for an extra buffer stage is eliminated, and the highest possible efficiency is achieved with the proper turns ratio selected. The generated digital control pulse signals are also used to ensure fast start-up and UWB operation while maintaining low power consumption with an implemented on/off tail switching scheme. The presented IR-UWB transmitter that occupies a total area of 0.35 mm2 is fabricated in the United Microelectronics Corporation (UMC) 180-nm mixed-mode/radio frequency (RF) CMOS process. The measured output voltage swing of the fabricated transmitter is 0.812 V on a 50-Ω load for the 200 Mb/s data rate, and the bandwidth is measured as 902 MHz. The achieved frequency tuning range is 1 GHz and the fabricated transmitter can drive 50 Ω, 75 Ω and 100 Ω loads with measured efficiency values 4.16%, 5.76%, and 4.05%, respectively. Compared to other works in the literature, this design achieves a higher output pulse energy at a higher data rate while maintaining low power consumption and, thus, high efficiency.

A 6-9 GHz 1.28 Gbps 76 mW Amplitude and Synchronized Time Shift Keying IR-UWB CMOS Transceiver for Brain Computer Interfaces.

This paper proposes a low-power, high-speed impulse radio-ultra-wideband (IR-UWB) transceiver for brain computer interfaces (BCIs) using amplitude and synchronized time shift keying technique (ASTSK). The proposed IR-UWB transmitter (Tx) generates two pulses (sync pulse and data pulse) per symbol rate. The time difference between two pulses is used for synchronized time shift keying and the amplitude of the two pulses is used for amplitude shift keying. The receiver (Rx) demodulates the time difference with a low power time-to-digital converter (TDC) and peak detector (PD) based amplitude demodulation is suggested to relax analog-to-digital converter (ADC) burden for low power receiver. Especially the Tx-based synchronized operation eliminates the need for complex clock circuitry such as phase-lock loop (PLL) and reference crystal oscillator. Therefore, it can achieve low power and high-speed operation. The prototype, fabricated in 65 nm CMOS, has a frequency range of 6-9 GHz, communication speed of 1.28 Gbps, and power consumption of 18 mW (Tx) and 58 mW (Rx). This work is a fully integrated RF transceiver adapted for high-order modulation and designed to include the receiver.

Design and Implementation of a Transmitter for IR-UWB Standard

In wireless communication, the Ultrawide Band (UWB) is a technique for achieving a higher data rate, low power consumption, and less complexity. Impulse Radio - Ultra-Wide Band (IR-UWB) uses the baseband signal technique, reducing circuit complexity and power consumption. This work proposes an IR-UWB transmitter block with low power and tunable bandwidth that meets the UWB regulations of LRP (Low-Rate Pulse) UWB. The transmitter proposed uses a time-interleaved architecture using 0.18um CMOS technology using Cadence Virtuoso, which consists of On Off Keying (OOK) Circuit for the four stages of a pulse generator that operates in 6.17GHz-9.10GHz. The width of the pulse is between 0.096ns to 0.162ns using a current steering inverter. The proposed transmitter block has an output swing of 30 mV at 1MHz input Pulse Repetition Frequency (PRF) and a maximum PRF of 1GHz, at a 1GHz pulse rate, the power consumption was measured to be 8.3 mW.

A 21.3%-Efficiency Clipped-Sinusoid UWB Impulse Radio Transmitter with Simultaneous Inductive Powering and Data Receiving.

An ultra-wide-band impulse-radio (UWB-IR) transmitter (TX) for low-energy biomedical microsystems is presented. High power efficiency is achieved by modulating an LC tank that always resonates in the steady state during transmission. A new clipped-sinusoid scheme is proposed for on-off keying (OOK)-modulation, which is implemented by a voltage clipper circuit with on-chip biasing generation. The TX is designed to provide a high data-rate wireless link within the 3-5 GHz band. The chip was fabricated in 130nm CMOS technology and fully characterized. State-of-the-art power efficiency of 21.3% was achieved at a data-rate of 230Mbps and energy consumption of 21pJ/b. A bit-error-rate (BER) of less than 10 -6 was measured at a distance of 1m without pulse averaging. In addition, simultaneous wireless powering and VCO-based data transmission are supported. A potential extension to a VCO-free all-wireless mode to further reduce the power consumption is also discussed.

IR-UWB Chipless RFID Reader Based on Frequency Translation Technique for Decoding Frequency-Coded Tags

The impulse radio ultra-wideband (IR-UWB) reader is the most promising technique to interrogate a frequency-coded chipless radio frequency identification (RFID) tag. However, challenges of receiving an ultra-wideband (UWB) pulse, such as complexity, high-noise bandwidth, low reading speed, and high cost, are yet to be addressed in IR-UWB readers. A combined solution based on an IR-UWB transmitter and a frequency translation (FT) method in the receiver is presented in this article. The tag is interrogated by a broadband pulse (3.1-10.6 GHz). In the receiver, instead of processing the entire wideband backscattered pulse in one run, the new architecture transposes the spectrum of the backscattered pulse to a 150-MHz intermediate frequency (IF) band. Hence, the noise bandwidth, cost, and complexity of the receiver are reduced significantly. Since the reading range plays a decisive role in reducing the complexity and cost, a detailed study of the design parameters of the reader, affecting the detection range, is performed. Then, a low-cost and straightforward reader is implemented, based on the outcomes of the parameters' study. It is shown that the reading range of the reader is competitive with that of the state-of-the-art readers and vector network analyzer (VNA), while the complexity, reading time, and cost are dropped.

A differential IR-UWB transmitter using PAM modulation with adaptive PSD

The current state of the telecommunications market exhibits a high potential to absorb efficient innovations in wireless connectivity, especially those that can be applied to the Internet of Things and similar domains. Contributing in that direction, this paper describes the design and implementation of a fully differential impulse-radio ultra-wideband (IR-UWB) transmitter using pulse-amplitude modulation, with an adaptive power spectrum density (PSD). The architecture can produce up to eight differential monocycles per clock pulse at its output. The number of monocycles controls the bandwidth (thus the PSD) in the mask of IR-UWB technologies, allowing adaptation to multiple standards. The complete transmitter has four main blocks: (a) a pulse generator, comprising two pulse generating circuit groups, to modulate and create a rectangular waveform; (b) an active balun with two amplifiers, to generate differential signals; (c) a digital demultiplexer, to alternate data to the pulse generating circuit groups; (d) a binary-to-thermometer decoder, to control the amount of generated monocycles per pulse. Simulations demonstrate an output pulse amplitude of 120 mV for the high logic level and of 70 mV for the low logic level, both at a 100 MHz Pulse Repetition Frequency. This produces a mean pulse duration of 277 ps, a mean central frequency of 3.8 GHz, and a mean power consumption 6.7 mW. The transmitter takes the form of an intellectual property core in a 130 nm CMOS technology. The complete transmitter area is 0.067 mm $$^2$$ , without I/O pads. The outcomes suggest that the proposed circuit can narrow or widen the output signal bandwidth, providing adaptability to different emission requirements.

Design and Optimization of Dual-Band Energy-Efficient OOK UWB Transmitter Via PSO Algorithm

A CMOS ON–OFF-keying 3–10.6-GHz transmitter with low power consumption and low complexity used to Impulse Radio Ultra-Wide Band (IR-UWB) communication system is presented in this work. This architecture is designed and optimized via particle swarm optimization (PSO) algorithm. The IR-UWB transmitter is adapted to generate a high bandwidth frequency and it has a band switching capability. It consists of a switching inductance–capacitance voltage-controlled oscillator (LC_VCO), a pulse generator circuit, an injection-locked frequency divider (ILFD) circuit, a buffer and an antenna. The VCO is switched ON/OFF by the pulse signal produced by a generator circuit which is realized through synchronizing the received data by a clock signal. The used technique for transmitting a discontinuous signal is based on a complementary switch-mode ON–OFF LC_VCO, whose main advantage is to reduce power consumption. In this work, a best agreement between the results of the optimization technique and those of the simulation is obtained. The simulated results illustrate a signal of pulse width of 2.5 ns and a pulse repetition rate (PRR) of 200 MHz. The output spectra are centered at 4-GHz and 8-GHz frequencies with 1,332-MHz and 1,350-MHz bandwidths, respectively. The peak-to-peak amplitude of a UWB signal output is 154[Formula: see text]mV. The IR-UWB transmitter power consumption is 11.4[Formula: see text]mW which corresponds to the consumption energy of 28.5 pJ/pulse @ 200[Formula: see text]MHz. The power spectral densities (PSDs) of the output signals of both circuits viz. ON–OFF LC_VCO and ILFD are less than [Formula: see text][Formula: see text]dBm/MHz, which agreed well with the Federal Communication Commission (FCC) regulation. The transmitter design is well implemented using a TSMC 0.18-[Formula: see text]m CMOS process technology in an Advanced Design System (ADS).

Area and Power Efficient 3–8.8-GHz IR-UWB Transmitter With Spectrum Tunability

An ultralow-power and low-complexity impulse radio ultrawideband (IR-UWB) transmitter (TX) is fabricated in the low-cost 180-nm United Microelectronics Corporation (UMC) CMOS technology. The TX offers control of the power spectral density (PSD) by using a tunable pulse generator and a controllable switched oscillator. It supports on-off keying (OOK) coding and occupies a total die area of 0.35 mm2. The measured results show the transmitter output amplitude of 130 mVp-p with the pulse width of 1.0 ns, and the PSD with 10-dB bandwidth from 3 to 8.8 GHz. The total dc power consumption is 0.6 mW, corresponding to the energy consumption of 3 pJ/pulse at 200-MHz pulse repetition frequency.

A Bandwidth and Frequency Calibration Method for OOK UWB-IR Transmitter with High Energy Efficiency

In this paper, an offline bandwidth and frequency calibration method for an on–off LC oscillator-based ultra-wideband impulse radio (UWB-IR) transmitter is presented. Implemented in 0.18-[Formula: see text]m CMOS, the offline calibration circuits consume very little power. This allows the transmitter to consume an ultra-low average power of 319[Formula: see text][Formula: see text]W over 3–5[Formula: see text]GHz at 2[Formula: see text]Mbps. The calibration is critical to ensure the FCC spectral mask compliance despite the process–voltage–temperature (PVT) variations. The transmitter can deliver a large differential output swing of 1.8–3[Formula: see text]V to a 100-[Formula: see text] load with minimal power efficiency of 7% at different data rates (2–30[Formula: see text]Mbps). It is suitable for WPAN application with localization and positioning capabilities.

An all-digital frequency tunable IR-UWB transmitter with an approximate 15th derivative Gaussian pulse generator

This work presents a new frequency-tunable, OOK–modulated, impulse-radio ultra-wideband (IR-UWB) transmitter, where approximate 15th derivative Gaussian pulses are produced by a monopulse-synthesis pulse generator. The center frequency of our output UWB pulses can be easily adjusted between 4 and 9 GHz by controlling delay time. Thus, the whole UWB frequency band from 3.1 to 10.6 GHz can be covered and utilized. Since the proposed monopulse-synthesis pulse generator already includes a pulse shaping function, RF bandpass filters are not required, thus realizing the extremely low complexity and small circuit area. The proposed IR-UWB transmitter has been implemented and fabricated in a standard 0.18 μm CMOS 1p6m process. The power supply voltage is 1.8 V and the targeted data rate is 31.25 Mbps. Chip measurement results show that the power spectrum density conforms to the FCC spectrum masks, and the peak-to-peak voltage of output UWB pulses is 56 mV. In addition, the core area of the chip is 0.02 mm2, the measured frequency tuning range is 3.1–10.6 GHz, and the measured energy dissipation is only 12.5 pJ/bit. Compared to the state-of-the-art designs in the literature, the chip area and tunable frequency range are improved by at least 33% and 53%, respectively.

Compact digital implementation of a non‐coherent IR‐UWB transmitter and receiver

Non-coherent impulse-radio ultra-wideband (IR-UWB) transceivers are attractive candidates for applications where the silicon area and power consumption are relatively limited. This study presents the compact digital architecture design and implementation of a non-coherent IR-UWB transmitter and receiver based on the energy detection scheme, including the synchroniser module. The software models of the designed transceiver are simulated and verified in both floating-point and fixed-point numerical representations. The synthesisable Verilog description of the transmitter and receiver architectures is simulated and verified against their fixed-point simulation model. The transmitter and receiver are implemented in the authors custom-developed field-programmable gate array (FPGA) board. The bit error rate performance of the transmitter and receiver is measured in real-time on the FPGA, utilising an accurate on-chip Gaussian noise generator. The characteristics and implementation results of the transmitter and receiver architecture on the FPGA are presented. An application-specific integrated circuit (ASIC) architecture of the IR-UWB transceiver is estimated to occupy 0.0227 mm 2 and dissipate 760 mW from a 1.0 V supply while operating at 82 MHz in a standard 32 nm complementary metal-oxide-semiconductor technology.

The Design of an Energy-Efficient IR-UWB Transmitter With Wide-Output Swing and Sub-Microwatt Leakage Current

In this brief, we present an impulse-radio ultra-wideband (IR-UWB) transmitter for low-power communication and radar sensing applications. To improve the leakage power for the IR-UWB transmitter, we have adopted transistor stacking technique in the design of our digitally controlled oscillator (DCO) and mask generator. The DCO and mask generator circuit generate the UWB carrier frequency and pulse mask signals, respectively. These signals are combined through a cascode output driver stage with an on-chip inductor load. The cascode structure significantly reduces the leakage power. The on-chip inductor load improves the transmitted pulse amplitude. As a result, our proposed transmitter has significantly reduced the leakage power to sub-micro watt and achieved a maximum amplitude of 0.94 V. Therefore, we are able to achieve a maximum efficiency of 8.6% and the transmitted energy per pulse is 3.6-pJ.

Area and Power Efficient Ultra-Wideband Transmitter Based on Active Inductor

This brief presents the design of an impulse radio ultra-wideband (IR-UWB) transmitter for low-power, short-range, and high-data rate applications such as high density neural recording interfaces. The IR-UWB transmitter pulses are generated by modulating the output of a local oscillator. The large area requirement of the spiral inductor in a conventional on-chip LC tank is overcome by replacing it with an active inductor topology. The circuit has been fabricated in a UMC CMOS 180-nm technology, with a die area of 0.021 mm2. The temporal width of the output waveform is determined by a pulse generator based on logic gates. The measured pulse is compliant with federal communications commission power spectral density limits and within the frequency band of 3–6 GHz. For the minimum pulse duration of 1 ns, the energy consumption of the design is 20 pJ per bit, while transmitting at 200-Mbps data rate with an amplitude of 130 mV.

Analysis and Implementation of a Gaussian Addition IR-UWB Transmitter for Increased Spectral Efficiency

This paper describes a technique to improve the spectral efficiency and increase the energy in the transmitted pulse of an impulse-radio, ultra-wideband (IR-UWB) transmitter utilizing bi-phase shift keying (BPSK) modulation and working in the frequency range of 3.1–10.6 GHz. Two Gaussian bi-phase pulses are produced and form the base-band signal. These two signals are delayed with respect to each other and are independently up-converted to a different region of the UWB spectrum. The two up-converted signals are then combined to form the final IR-UWB BPSK output signal. The IR-UWB output signal is analyzed in both the time domain and frequency domain to determine time-bandwidth product and spectral efficiency ( $$\eta $$ ). By combining the two up-converted gaussian signals, the spectral efficiency is increased to 77% and the time-bandwidth product of the output signal is 1.7. For a transmitter operating at a data rate of 250 Mbps, the energy per pulse of the output signal can be increased to 4.33 pJ while staying within the FCC spectral and power limits. This technique can also be used to produce a −30 dB notch at 5.9 GHz to further reduce any interference from an IEEE 802.11p Wifi signal.

A Miniature Mode Reconfigurable Inductorless IR-UWB Transmitter–Receiver for Wireless Short-Range Communication and Vital-Sign Sensing

This paper presents a miniature inductorless impulse-radio ultra-wideband transmitter–receiver and radar for wireless short-range communication and vital-sign sensing. The all-digital transmitter generates impulse-radio ultra-wideband pulses using edge combining technique and consumes 21.6 pJ/pulse at 10 Mb/s. A novel active-inductor-based technique is proposed for low noise amplifier that achieves ultra-wideband input impedance matching in the receiver. The non-coherent receiver employs a simple demodulation and synchronization circuit to achieve self-synchronization without any on-chip or external oscillator. Consuming a total power of 6.4 mW, the receiver attains −64-dBm sensitivity at 10 Mb/s. The chip is implemented in a 65-nm digital CMOS process and occupies only 0.04 mm2. Measurement shows that the transmitter–receiver and radar is capable of sensing the human’s respiratory rate when the time interval is measured by a fast sampling digital oscilloscope.

A CMOS 6–10 GHz impulse radio UWB transmitter based on gated oscillator with switching pulse shaper

In an impulse radio ultra-wideband (IR-UWB) system for low-power location-aware sensor networks, the output pulses must meet the FCC spectral emission mask. In addition, to increase battery life, the IR-UWB transmitter must be energy efficient. In this paper, a CMOS ultra-wideband (UWB) transmitter designed using a 0.11-μm process is presented for 6–10 GHz applications. To reduce energy consumption, the transmitter adopts a gated voltage-controlled oscillator (VCO) that directly drives 50 Ω output impedance. A gated VCO that uses a trapezoidal pulse for on/off gating of the tail current source satisfies the spectrum mask without requiring an additional pulse shaping filter. The active energy consumption is 13.4 pJ/pulse at a pulse repeating frequency (PRF) of 40 MHz. The side-lobe rejection performance is more than 30 dB.

A Low-Power Wireless Piezoelectric Sensor-Based Respiration Monitoring System Realized in CMOS Process

This paper presents a methodology of monitoring respiration pattern using piezoelectric transducer incorporating CMOS integrated circuits for signal processing and data transmission. As a proof of concept, the system has been tested by placing electrodes on human chest using adhesive hydrogel to detect the pulsatile vibration due to respiration. The system can be used either as a wearable device itself or alternatively can be attached to a jacket or a chest belt. The front-end transducer is a piezoelectric material-based sensor, which is comprised of a ferroelectric polymer named polyvinylidene-fluoride (PVDF). PVDF is also biocompatible, which makes the sensor suitable to be used as a wearable device. The charge produced by the sensor is converted to a proportional voltage signal with the help of a charge amplifier designed in a standard 130-nm CMOS process with eight metal and one poly layer. The analog voltage signal acquired from the charge amplifier is then converted into a digital signal using a reconfigurable pipelined analog-to-digital converter for ease of transmission. An impulse-radio ultra-wideband transmitter operating in the frequency range of 3.1–5 GHz is designed for wireless transmission of the data. The smaller footprint, lighter weight, wireless telemetry, and low-cost material along with the low-power integrated CMOS circuitry for signal processing and data transmission make the proposed system an attractive choice for stable respiration monitoring system.

A short-impulse UWB BPSK transmitter for large-scale neural recording implants.

In this paper, a short-impulse ultra-wide band (UWB) transmitter is introduced to enable large-scale neural recordings within miniature brain implants including thousands of channels. The proposed impulse radio UWB transmitter uses a BPSK modulation scheme, the carrier signal of which uses only two delayed impulses to encode the transmitted signal. The proposed UWB transmitter has been implemented into a CMOS 180 nm technology. It occupies 300 μm × 230 μm, and consumes only 6.7 pJ/bit from a 1.8-V supply. Experimental results show that the transmitter has a bandwidth of 2.6 GHz to 5.6 GHz and achieves a maximum data rate of 800 Mbps, which outperforms existing low-power UWB transmitters for similar applications.

CMOS impulse radio ultra‐wideband Gaussian pulse generator with variable channel and bandwidth

A Gaussian pulse generator for an ultra-wideband impulse radio transmitter is presented. The proposed generator is based on digital intensive circuits, and the centre frequency and bandwidth of a pulse are controlled by a digitally tunable delay circuit and pulse-width control circuit. The Gaussian pulse is obtained by a weighted summing amplifier that is controlled by a digital switching signal without an additional LC filter. The amplifier uses a Gaussian pulse shaper that has tunable weighting factors with bandwidth control. The energy consumption of the pulse generator is 37.4 pJ/pulse, and sidelobe rejection of 20 dB is achieved without a filter.

A 2.89 μW Dry-Electrode Enabled Clockless Wireless ECG SoC for Wearable Applications

This paper presents a fully integrated wireless electrocardiogram (ECG) SoC implemented in asynchronous architecture, which does not require system clock as well as off-chip antenna. Several low power techniques are proposed to minimize power consumption. At the system level, a newly introduced event-driven system architecture facilitates the asynchronous implementation, thus removes the system clock leading to a true ECG-on-chip solution. A DC-coupled analog front-end is introduced together with a baseline stabilizer to boost the input impedance to 3.6 GQ and mitigate the electrode offset, which is less sensitive to motion artefact and contact impedance imbalance, making it well suited for dry-electrode based applications. Level-crossing analog-to-digital converter (LC-ADC) is employed to take the advantage of burst nature of ECG signal leading to at least 5 times reduction in sampling points compared to Nyquist sampling. A digitally implemented impulse-radio ultra-wideband transmitter is seamlessly integrated with LC-ADC and an on-chip antenna for wireless communications. Implemented in 0.13 μm CMOS technology, the ECG-on-chip consumes 2.89 μW under 1.2 V supply while transmitting the raw ECG data, which attains one order of magnitude lower than the current state-of-the-art designs. The fully integrated ECG SoC requires no external clocks and off-chip antenna, making it a good candidate for low cost and disposable wireless ECG patches, such as epidermal electronics.