Digital Amplifier Research Articles

Thermal Pyranometer Using the Open Hardware Arduino Platform

Thermal Pyranometers are very important devices for evaluating the intensity of solar radiation under different climatic conditions. These devices utilize thermal radiation for comparison and determination of their efficiency. Because of this wide use associated with the development of new technologies, a simple and low-cost version of thermal pyranometer has been studied, designed and manufactured. A blackened aluminum disk is used as a hot junction, and the cold junction is exposed to ambient air. The two terminals are connected to a digital amplifier with output signal directed to an Arduino board. A device calibration was performed by comparing the results with a commercial photodiode sensor. Statistical analysis of the calibration data considering a 99% confidence level leads to an estimated standard error of 20.8 W/m². An analysis of its response time also estimated from a dynamic model. This model uses a numerical solution of the energy balance on heat exchange between the aluminum disc and the environment. The instrument response time based on the average of the estimates obtained from the dynamic model is about 1.5 minutes. Based on these studies it was concluded that the characteristics of the sensor are adequate for most solar energy tests and the final cost of US $ 60.00 is much lower than the large majority of such commercial devices.

Wide digitally tunable lowpass filter for biomedical and wireless applications

A fully differential Gm-C lowpass filter for wireless and biomedical applications is introduced in this Letter. The proposed filter is based on a highly linear CMOS digital programmable operational transconductance amplifier (DPOTA).The filter consists of a parallel connection of three fourth-order Butterworth sections. Each section is optimised for a specific band of frequencies which can be tuned digitally. Switching between the different sections is achieved by controlling the corresponding DPOTAs' transconductance values, hence, this filter design eliminates the need for switches. Simulation results for a 90 nm CMOS technology are given. The third-order harmonic distortion (HD3) of the DPOTA remains below −60 dB up to 0.5 V differential input voltage at 1.2 V supply voltage. The proposed filter exhibits a wide cutoff frequency tuning range, from 100 Hz to 12 MHz, thus it covers many biomedical and wireless communication standards.

Electrical Activity of the Bladder Is Attenuated by Intravesical Inhibition of P2X2/3 Receptors During Micturition in Female Rats.

PurposeTo simultaneously monitor electrical discharges in various bladder regions and the external urethral sphincter (EUS) during voiding contractions, and to assess the functional role of myogenic modulation of the lower urinary tract (LUT) by ionotropic purinergic receptors containing the P2X3 subunit.MethodsFemale Sprague-Dawley rats were anesthetized with urethane, and implanted with a suprapubic catheter for open cystometry. Flexible microelectrodes were placed ventrally in the bladder dome, upper bladder, lower bladder, and bladder base, along with the middle section of the exposed EUS. Intravesical P2X3-containing receptors were blocked with AF-323, a specific P2X3-P2X2/3 receptor antagonist. A digital electrophysiology amplifier was used to record electrical and cystometric signals throughout the LUT.ResultsElectrical activity in the LUT started before effective voiding contractions. Bladder pressure and electrical waveforms showed consistent out-of-phase activity when compared with the recordings made at the EUS. This pattern was also observed during voiding contractions in the presence of AF-353, supporting the hypothesis that during bladder distension, activation of P2X3-containing receptors is required for voiding contractions. Furthermore, the inhibition of P2X3-containing receptors significantly decreased the amplitude of electrical signals in the urinary bladder, but not the base or EUS.ConclusionsOur results provide novel information about the regulation of the micturition process by P2X3-containing receptors located in the inner layers of the bladder.

Hybrid Linearized Class-BD Double Sided (LBDD) Digital Pulse Width Modulator (DPWM) for Class-BD Audio Amplifiers

The paper presents an original architecture and implementation of 9-bit LBDD hybrid DPWM circuit for Class-BD digital audio amplifier. The input PCM signals are directly transformed into 24-bit LBDD DPWM signals and then are requanized to the 9-bit digital outputs using noise-shaping process to support high fidelity with practical values of time resolution, and finally are converted by the DTCs into the two physical trains of 1-bit PWM signals. The architecture of the proposed Class-BD hybrid DPWM circuit is composed of two Class-AD ones. The hybrid quantizer converts 6 MSB bits using counter method, based on the STM32F407xx microcontroller, while the remaining 3 LSB bits - using a method based on the Programmable Tapped Delay Line (PTDL). All necessary time waveforms are generated on the base of the internal microcontroller oscillator 168 MHz. The proposed 9-bit Class-DB DPWM circuit allows to attain SNR of 110 dB and THD about 0,2% within the audio baseband, at switching frequency of 328.1 kHz, clock frequency of 42 MHz and modulation index M = 0.95. Basic verification of algorithm and circuit operation as well as simulation and preliminary experimental results have been performed.

A 95-dBA DR Digital Audio Class-D Amplifier Using a Calibrated Digital-to-Pulse Converter

A digital class-D amplifier (CDA) converts an audio digital stream into sound directly and power-efficiently. It first encodes the pulse-code-modulated audio input into a digital pulse-width-modulated (PWM) signal. It needs a digital-to-pulse converter (DPC) to translate this digital PWM signal into a series of analog binary pulses accurately. We report a 5-3 segmented DPC that includes both a counter and a delay line for pulse width conversion. The timing skews along the delay line are detected using a zero-crossing detection scheme and corrected in the digital domain. This calibration can operate continuously in the background. A digital CDA prototype was fabricated using a 65-nm CMOS technology. It includes the aforementioned PWM modulator and DPC. It also integrated an open-loop switching driver to deliver the DPC’s output to a speaker. This digital CDA consumes $875~ {\mu }\text {W}$ under a 1-V supply when the input is zero and no output power is transferred to the external load. It can deliver 13.3 mW to a $32~ {\Omega }$ resistive load in the H-bridge topology with 89% power efficiency. For a 1-kHz sine-wave input, it achieves 95 dBA dynamic range, 93.6 dBA peak SNR, 86.4 dBA peak SNDR, and 0.006% THD at -2-dBFS input level. The core area of the chip is $ {0.87\times 0.5\,\,\text {mm}^{2}}$ .

Development of a multi frequency impedance measurement system for use in MEMS flow cytometers

A novel MEMS based system for flow cytometry is presented based on a multispectral approach. The solution provides the ability to concurrently generate, detect and analyse the response from a biological cell using multiple narrow band signals with a frequency separation sufficient to evoke different cellular responses. The narrow band approach limits the energy required and provides an improved signal to noise ratio for a given transmitter energy, avoiding wide band signal power dissipation and dilution issues. It requires only a single transmitter and receiver interface to the MEMS device with no duplication of analogue signal paths. The design has the ability to generate a complex multi frequency waveform with a wide frequency separation. A digital approach based on the CORDIC algorithm (Volder, IRE Trans Electron Comput EC-8:330–334, 1959) was used to generate the required sinusoidal waveforms. The digital section of the design was implemented on an FPGA. It utilised a modified digital phase sensitive amplifier to provide enhanced signal to noise performance and harmonic rejection. A novel hybrid, cross channel electrode structure to implement the stimulus and response analysis sub-system has been designed. A fully functional macroscopic test bench has been constructed to demonstrate the viability of the approach. Both physical measurements and finite element data has been used to demonstrate the potential for migration into a MEMS based system.

A versatile Lock-In digital Amplifier (LIdA): the case of mechanical resonances

The assembly of a Lock-In digital Amplifier (LIdA) from widely accessible ready-made modules is presented. This equipment, which does not require any advanced knowledge of electronics or programming, may introduce the experimenter to resonant techniques by registering mechanical resonances. The freely available control program allows for general data acquisition and further data processing. The apparatus is versatile and may corroborate the science and engineering laboratory in elasticity measurements or in a series of experiments where a modulated signal is a prerequisite.

Analysis and Design of a Linear Digital Programmable Gain Amplifier in a 0.13 µm SiGe BiCMOS technology

AbstractThis paper presents the analysis and the design of a fully-differential digital programmable gain amplifier (PGA) in a 0.13 µm BiCMOS technology. The PGA has a gain control range of 31 dB with 1 dB gain step size and consumes 284 mW from a 3.6 V power supply. At a maximum gain of 25 dB, the PGA exhibits a 3-dB bandwidth of 10.1 GHz. The measured gain error for all 32 possible gain settings is between –0.19/+0.46 dB at 1 GHz. Up to 13 GHz the third harmonic distortion

Behavioral Modeling of Outphasing Amplification Systems

This paper presents a comparison of existing and novel behavioral models targeted at the outphasing power amplifier (PA) architecture. A comprehensive comparison of ten modeling strategies is presented in the results. Novel techniques for outphasing PAs, such as vector switched and dual path time series, are also presented for the first time. Investigation of such techniques was driven by the analysis of outphasing operation at minimum output powers, demonstrating the generation of frequency-dependent amplitude and phase deviations, which can be difficult to characterize. The increased robustness was achieved at the cost of additional complexity; for practical implementation, time series coefficient reduction techniques were also evaluated. The results of all modeling approaches are experimentally validated for the wideband operation of an NXP 19-W GaN digital outphasing amplifier module. Considering computational complexity and accuracy for system-level modeling across all presented options, a subset of existing and new models is identified as best suited for modeling outphasing PAs.

Circuit implementation of digitally programmable transconductance amplifier in analog simulation of reaction-diffusion neural model

This paper is concerned with circuit implementation in reaction-diffusion neuron model. Firstly, in order to realize easily, one obtains the equivalent form by discretization of this neuron model. In the frame of discrete model, every parameter can be represented by the basic circuit component. Then the digital programmable transconductance amplifier (DPTA) is designed to realize the digitally function in circuit. In addition, the DPTA is applied to realize two activation functions and the simulation results are verified in Multisim.

Performance comparison of adaptive digital predistortion algorithms using adaptation time for mobile WiMAX power amplifier applications

In this paper, we propose that adaptation time be considered a parameter for evaluating the performance of digital filter algorithms in adaptive digital predistorted high-power amplifiers. An adaptive predistorted high-power amplifier with an average power of 37.5 dBm was designed and fabricated for mobile worldwide interoperability for microwave access (WiMAX) test signals. For performance comparisons using adaptation time, several effective algorithms (such as the least-mean-squares (LMS), recursive-least-squares (RLS), and affine projection (AP) algorithms) were implemented. According to the experimental results, the RLS and AP algorithms achieved a similar linearity improvement of 11 dBr. However, the AP algorithm had the advantage of a faster adaptation time than the other algorithms.

数字正交锁相放大器的研制及其在甲烷检测中的应用

数字正交锁相放大器的研制及其在甲烷检测中的应用

Automated Patch Clamp Meets High-Throughput Screening: 384 Cells Recorded in Parallel on a Planar Patch Clamp Module.

We have developed an automated patch clamp module for high-throughput ion channel screening, recording from 384 cells simultaneously. The module is incorporated into a laboratory pipetting robot and uses a 384-channel pipettor head for application of cells and compounds. The module contains 384 amplifier channels for fully parallel recordings using a digital amplifier. Success rates for completed experiments (1- to 4-point concentration-response curves for cells satisfying defined quality control parameters) of greater than 85% have been routinely achieved with, for example, HEK, CHO, and RBL cell lines expressing hNaV1.7, hERG, Kir2.1, GABA, or glutamate receptors. Pharmacology experiments are recorded and analyzed using specialized software, and the pharmacology of hNaV1.7 and hERG is described. Fast external solution exchange rates of <50 ms are demonstrated using Kir2.1. Short exposure times are achieved by stacking the external solutions inside the pipette of the robot to minimize exposure of the ligand on the receptor. This ensures that ligand-gated ion channels, for example, GABA and glutamate described in this report, can be reproducibly recorded. Stem cell-derived cardiomyocytes have also been used with success rates of 52% for cells that have a seal resistance of >200 MΩ, and recordings of voltage-gated Na+ and Ca2+ are shown.

A WCDMA/WLAN Digital Polar Transmitter With Low-Noise ADPLL, Wideband PM/AM Modulator, and Linearized PA

This paper presents a single-chip digital-intensive polar transmitter for WCDMA and WLAN integrating a low-phase-noise all-digital phase-locked loop (ADPLL), a digitally-controlled wideband phase/amplitude modulator, and a calibration-free high-linearity power amplifier. From the ADPLL, the 1.7–2.5 GHz LO signal is generated together with a ${\div} $ 1.5 frequency divider to eliminate DCO pulling. The phase noise of the ADPLL is optimized by using a linearized stochastic TDC with 3 ps resolution and a Class-C quadrature DCO (QDCO) with embedded quadrature phase shifter and quantization-noise filter. A 2-segment $\Sigma \Delta$ switching phase modulator enhances the PM bandwidth up to 200 MHz, and a digital polar amplifier employs AM-replica linearization to eliminate AM pre-distortion. The TX achieves a ${-}$ 1 dB output compression point of 22.8 dBm with an overall system efficiency of 27.6% and measures EVM of 4% for a 20 MHz 64-QAM signal at an output power of 13.8 dBm.

Power-Optimized Temperature-Distributed Digital Data Link

Interfacing superconducting rapid single flux quantum logic with room temperature electronics requires the development of low-power semiconductor circuitry capable of operating at tens of Gb/s while maintaining sufficient signal to noise to achieve acceptable bit-error-rates. Such data-links must operate with sufficiently low power consumption to permit tens to hundreds of parallel channels to coexist in a single cryostat. This requires a careful trade-off between the power and noise performance of the cryogenically cooled digital amplifiers. Previously demonstrated ultra low-power cryogenic-to-room temperature digital data links have been limited to data rates on the order of a few Gb/s. In this paper we demonstrate a temperature distributed amplifier chain optimized for 30 Gb/s data transmission and consuming just 140 microwatts at 4 K.

Detection of pathological biomarkers in human clinical samples via amplifying genetic switches and logic gates.

Whole-cell biosensors have several advantages for the detection of biological substances and have proven to be useful analytical tools. However, several hurdles have limited whole-cell biosensor application in the clinic, primarily their unreliable operation in complex media and low signal-to-noise ratio. We report that bacterial biosensors with genetically encoded digital amplifying genetic switches can detect clinically relevant biomarkers in human urine and serum. These bactosensors perform signal digitization and amplification, multiplexed signal processing with the use of Boolean logic gates, and data storage. In addition, we provide a framework with which to quantify whole-cell biosensor robustness in clinical samples together with a method for easily reprogramming the sensor module for distinct medical detection agendas. Last, we demonstrate that bactosensors can be used to detect pathological glycosuria in urine from diabetic patients. These next-generation whole-cell biosensors with improved computing and amplification capacity could meet clinical requirements and should enable new approaches for medical diagnosis.

Flexible black phosphorus ambipolar transistors, circuits and AM demodulator.

High-mobility two-dimensional (2D) semiconductors are desirable for high-performance mechanically flexible nanoelectronics. In this work, we report the first flexible black phosphorus (BP) field-effect transistors (FETs) with electron and hole mobilities superior to what has been previously achieved with other more studied flexible layered semiconducting transistors such as MoS2 and WSe2. Encapsulated bottom-gated BP ambipolar FETs on flexible polyimide afforded maximum carrier mobility of about 310 cm(2)/V·s with field-effect current modulation exceeding 3 orders of magnitude. The device ambipolar functionality and high-mobility were employed to realize essential circuits of electronic systems for flexible technology including ambipolar digital inverter, frequency doubler, and analog amplifiers featuring voltage gain higher than other reported layered semiconductor flexible amplifiers. In addition, we demonstrate the first flexible BP amplitude-modulated (AM) demodulator, an active stage useful for radio receivers, based on a single ambipolar BP transistor, which results in audible signals when connected to a loudspeaker or earphone. Moreover, the BP transistors feature mechanical robustness up to 2% uniaxial tensile strain and up to 5000 bending cycles.

A 40-nm CMOS, 1.1-V, 101-dB Dynamic-Range, 1.7-mW Continuous-Time &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$\Sigma\Delta$&lt;/tex&gt; &lt;/formula&gt; ADC for a Digital Closed-Loop Class-D Amplifier

This paper presents a continuous-time third-order ΣΔ modulator designed for closing the feedback loop of a digital class-D audio amplifier. The closed-loop digital class-D amplifier fully exploits the potential of the used 40-nm CMOS technology to achieve at the same time the flexibility of digital implementations and the performance of analog solutions. The proposed ΣΔ modulator consumes 1.7 mW from a 1.1-V power supply, achieving 101-dB dynamic-range (DR) and 72-dB peak signal-to-noise and distortion ratio (SNDR). The active-RC implementation allows the 1.1-V ΣΔ modulator inputs to be directly connected to the 5-V class-D amplifier power stage outputs and inherently guarantees third-order anti-aliasing filtering.

Linearization of an Outphasing Amplifier for Wide-band Multi-carrier Signals

A novel method using self-organizing maps to determine the optimum ranges to partition the vector switched Volterra series is presented. Analyzing characteristics of the input signal it is possible to separate different regions of operation. Partitioning of the correction algorithm provides the ability to target regions of different non-linear behavior with separate coefficients. This work is validated with experimentally measured results and shows an adjacent channel power ratio (ACPR) of $-49/-50$ dBc achieved for a four carrier Wideband Code-Division Multiple Access (WCDMA) signal using a 19 watt digital outphasing amplifier from NXP.

Digital amplification of T cell receptor signals

Immunology The kinase PKD2 is activated in T cells of the immune system when a peptide antigen binds to and stimulates the T cell receptor (TCR). Navarro et al. found that low concentrations of a peptide antigen activated PKD2 in a small proportion of T cells. In response to increased amounts of peptide antigen, a greater proportion of T cells exhibited maximal PKD2 activation. Thus, PKD2 may act as a digital amplifier of TCR signals, so that T cells mount an immune response tailored to the strength of the stimulus. Sci. Signal. 7 , ra99 (2014).