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Application Notes

AN-1309: A Range Extension Reference Design Using the ADF7023 and RFFM6901 915 MHz ISM Band Transmit Receive Module with Diversity Switch

This 8-page Application Note describes a reference design that improves the overall link budget by extending the range of the ADF7023 ISM band transceiver by almost 20 dB. In a non-interference-limited line-of-sight scenario, this equates to a range increase of approximately six to seven times. The design, which consists of an ADF7023 transceiver and an RFFM6901 front-end module, is suitable for operation in the 902 MHz to 928 MHz ISM band and complies with FCC regulations.

AN-1308: Common-Mode Step Response of Current Sense Amplifiers

Current sense amplifiers are used to amplify small differential signals in the presence of large common-mode voltages, to measure the voltage across a shunt resistor, for example. Current sense amplifiers can operate with supply voltages as low as 1.8 V and withstand input common-mode voltages as high as 600 V. Many applications, including H-bridge motor drivers, solenoid controllers, and dc-to-dc switching converters, have common-mode voltages that vary as a function of time. An ideal current sense amplifier does not react to the input common-mode variation, but real current sense amplifiers have finite common-mode rejection, typically specified at about 100 μV/V (80 dB) at dc. This Application Note focuses on the common-mode step response of current sense amplifiers.

AN-1292: Reed-Solomon Forward Error Correction and the ADF7023

This 7-page Application Note describes the Reed-Solomon firmware module, which contains both forward error correction and advanced encryption standard (AES) encryption, for the ADF7023 transceiver. Reed-Solomon encoding appends check symbols to the transmitted data. When received, these symbols detect the presence of errors and correct them in the received data. The firmware module is flexible, allowing the user to select values that enable correction of up to five error bytes within a packet. Encoded packets are resilient to burst and random errors; their coding gain improves link margin.

AN-1285: ADF7021-N Radio Performance for Wireless Meter-Bus (WM-Bus), Mode N

This 11-page Application Note describes the radio performance of the ADF7021-N transceiver when configured for operation according to the wireless meter-bus (WM-Bus) standard, focusing on key receiver parameters applicable to the 2.4 kbps and 4.8 kbps modes of operation. These parameters are packet error rate (PER) over power, sensitivity over carrier frequency error, blocking, and adjacent channel selectivity.

AN-1278: Autonomous IR Calibration on the ADF7023

Heterodyne radios, such as the ADF7023 family of transceivers, use a mixer to downconvert received radio frequency (RF) signals to an intermediate frequency (IF). Interfering signals, called interferers, that lay on the image frequency are also mixed down to the wanted frequency. This desensitizes the receiver, resulting in blocking on the wanted channel. In theory, an ideal transceiver, which employs an IQ receive architecture, can be configured to eliminate the image frequency mixing onto the wanted channel. This theory assumes that the gain balance and the phase orthogonality of the mixer quadrature paths are perfectly aligned. In practice, some imbalance exists due to imperfections in the mixer. The image calibration process adjusts the gain and phase of the mixer via a firmware download module, until the quadrature signals are optimally balanced, providing maximum image rejection. This 6-page Application Note describes the fully autonomous image rejection (IR) calibration firmware download module for the ADF7023 transceiver IC. With minimum user input, this firmware optimizes the image rejection with a default configuration completely autonomously.

Circuits from the Lab

CN0340: True RMS RF Detector with 95 dB Detection Range

This true rms responding power detector uses a variable gain amplifier (VGA) and a power detector to provide a 95-dB wide detection range, making it useful for accurate measurement of signals with diverse or varying crest factors, such as those found in GSM/EDGE, CDMA, WCDMA, TD-SCDMA, and LTE receivers and transmitters. The 65-dB detection range of the ADL5902 rms detector is extended to 95 dB by the addition of the AD8368 linear-in-dB VGA.

CN0325: PLC/DCS Universal Analog Input Using Either 4 or 6 Pin Terminal Block

This circuit provides two, 16-bit, fully isolated, universal analog input channels suitable for programmable logic controller (PLC) and distributed control system (DCS) modules. Both channels are software programmable and support a number of voltage and current ranges and thermocouple and RTD types. The inputs are protected for dc overvoltage conditions of 30 V. The demonstration board contains two fully isolated universal input channels: in one, the voltage, current, thermocouple, and RTD inputs all share the same terminals to minimize the number of pins required; in the other, separate terminals for voltage/current inputs and thermocouple/RTD inputs provides a lower part count and component cost.

CN0320: An IQ Demodulator-Based IF-to-Baseband Receiver with IF and Baseband Variable Gain and Programmable Baseband Filtering

This flexible, frequency agile, direct conversion IF-to-baseband receiver features a fixed 5-dB conversion gain to reduce the cascaded noise figure. Variable baseband gain adjusts the signal level, and a programmable low-pass filter eliminates out-of-channel blockers and noise. The filter bandwidth can be dynamically adjusted as the input signal bandwidth changes, ensuring full use of the available dynamic range of the driven ADC. The core circuit is an integrated I/Q demodulator with fractional-N PLL and VCO. With a single variable reference frequency, the PLL/VCO can provide a local oscillator (LO) between 750 MHz and 1150 MHz.

CN0314: Configurable 4-20 mA Loop Powered Transmitter/Receiver using a Micropower Instrumentation Amplifier

This configurable 4 mA-to-20 mA loop-powered transmitter is based on an industry-leading micropower instrumentation amplifier. Total unadjusted error is less than 1%. It can be configured with a single switch as either a transmitter that converts a differential input voltage into a current output, or as a receiver that converts a 4 mA-to-20 mA current input to a voltage output. Optimized for precision, low noise and low power industrial process control applications, the circuit can accept 0 V to 5V or 0 V to 10 V input range as a transmitter. As a receiver it can provide 0.2 V to 2.3 V or 0.2 V to 4.8 V output range compatible with ADCs using 2.5 V or 5 V references. The supply voltage can range from 12 V to 36 V as a transmitter and 7 V to 36 V as a receiver. The circuit is configurable, so a single hardware design can be used as a backup for both transmitter and receiver at the same time, minimizing inventory requirements.

CN0312: Dual-Channel Colorimeter with Programmable Gain Transimpedance Amplifiers and Synchronous Detectors

This dual-channel colorimeter, which features a modulated light source transmitter and a synchronous detector receiver, measures the ratio of light absorbed by the sample and reference containers at three different wavelengths, providing an efficient solution for many chemical analysis and environmental monitoring instruments that measure concentrations and characterize materials through absorption spectroscopy.

New Product Briefs

September 2014

30-V, low-noise, low-power, Operational Amplifier provides rail-to-rail inputs/outputs

ada4084-1The ADA4084-1 op amp features rail-to-rail inputs and outputs. It specifies 100-V max offset at room temperature, 0.5-V/C offset drift, 9.9-MHz unity gain bandwidth, 4.6‑V/s slew rate, 124-dB common-mode rejection, 117‑dB large-signal voltage gain, 120-dB power-supply rejection, and 3.9-nV/√Hz noise. This combination of wide bandwidth, low noise, and dc precision makes it useful in a wide variety of single- and dual-supply applications that require both ac performance and dc precision, including filters, portable telecom equipment, and sensor signal conditioning. Operating on a single 3.0-V to 36-V supply or dual 1.5-V to 18-V supplies, the ADA4084-1 draws 625 A. Available in an 8-lead SOIC package, it is specified from 40C to +125C and priced at $1.50 in 1000s.

105-MHz, low-noise, low-power, low-drift Operational Amplifier

ada4805-1The ADA4805-1 high-speed op amp offers a rail-to-rail output, 125-μV maximum input offset voltage, 105-MHz unity-gain bandwidth, 160-V/μs slew rate, 5.9 nV/√Hz voltage noise, and 0.6 pA/√Hz current noise, making it ideal for low-power, high-resolution data-acquisition systems. Its 495-A quiescent current is reduced to 3 A in shutdown mode; the output settles to 16 bits within 3 s from shutdown to fully on, allowing the amplifier to be turned off between ADC samples. The ADA4805-1 operates on a single 2.7-V to 10-V supply or dual 1.35-V to 5-V supplies. Available in 6-lead SC70 or SOT23 packages, it is specified from 40C to +125C and priced from $0.95 in 1000s.

Single and dual Comparators have known power-up state

adcmp391The single ADCMP391 and dual ADCMP392 low-power comparators with rail-to-rail inputs feature a common-mode input voltage range that extends 200 mV beyond the rails, 1-mV offset voltage across the full common-mode range, and an undervoltage lockout (UVLO) monitor, making them ideal for general-purpose and battery powered applications. The outputs have a defined state upon power-up, remaining at logic low until the supply voltage exceeds the UVLO threshold. Operating on a 2.3-V to 5.5-V supply, the ADCMP391/392 draw 19/22 A. Available in 8-lead SOIC packages, they are specified from 40C to +125C and priced at $0.25/$0.34 in 1000s.

4-input, 4-output, Adaptive Clock Translator for multiservice line cards

ad9554-1The AD9554-1 low-loop-bandwidth clock translator provides jitter cleanup and synchronization for many systems, including synchronous optical networks (SONET/SDH). It generates an output clock synchronized to up to four external input references. The digital PLL (DPLL) reduces input time jitter and phase noise associated with the external references. The digitally controlled loop and holdover circuitry continues to generate a low-jitter output clock even when all reference inputs have failed. Four differential clock outputs at frequencies from 430 kHz to 941 MHz are individually configurable for HCSL-, LVDS-, or LVPECL compatibility. The devices support GR-1244 Stratum 3 stability in holdover mode, Telcordia GR‑253 jitter specifications in up to OC-192 systems, and ITU-T G.8262 synchronous Ethernet slave clocks. Operating on 1.8-V and 3.3-V supplies, the AD9554-1 dissipates 920 mW in typical configurations and 164 mW in power-down mode. Available in a 56-lead LFCSP packages, it is specified from 40C to +85C and priced at $20.81 in 1000s.

Dual digitally controlled RF VGA operates from 100 MHz to 4000 MHz

adrf6573The ADRF6573 dual high-performance, digitally controlled, variable-gain amplifier (VGA) operates from 100 MHz to 4000 MHz. Each channel includes a 6-bit digital step attenuator (DSA) with a 31.5-dB gain control range, 0.5-dB steps, and 0.25-dB gain accuracy. The attenuation is controlled using an SPI-compatible serial interface. Each broadband linear amplifier operates up to 4000 MHz, with internal 50-Ω matching at the input and output. Only ac coupling and power supply decoupling capacitors are required for operation. Operating from a 4.75-V to 5.25-V supply, the ADRF6573 draws 85 mA per channel. Available in a 32-terminal LGA package, it is specified from 40C to +85C and priced at $7.50 in 1000s.

August 2014

Low-power, sub-GHz ISM/SRD, FSK/GFSK Transceiver IC is easy to use

adf7024The ADF7024 ultralow-power integrated transceiver uses the license-free ISM bands at 433 MHz, 868 MHz, and 915 MHz. Its ease-of-use and high performance make it suitable for a wide variety of wireless applications operating under European ETSI EN300-220, North American FCC Part 15, and other similar regulatory standards. The transceiver operates with six predefined radio profiles covering common data rate and modulation options. This ensures that the RF communication layer works seamlessly, allowing the user to concentrate on the protocol and system level design. The low-IF receiver minimizes power consumption and provides excellent sensitivity. Exceptionally linear, it is resilient to the presence of interferers in spectrally noisy environments. The highly efficient transmitter has programmable output power up to 13.5 dBm and automatic power amplifier (PA) ramping to meet transient spurious specifications. The RF frequency synthesizer comprises a voltage controlled oscillator (VCO), a low-noise fractional-N phase-locked loop (PLL) and a loop filter. This agile frequency synthesizer facilitates frequency-hopping spread spectrum (FHSS) systems. The ADF7024 operates on a 2.2-V to 3.6-V supply. Available in a 32-lead LFCSP package, it is specified from 40C to +85C and priced at $1.59 in 1000s.

0.5-GHz to 43.5-GHz Envelope Detector has fast response, 45-dB range

adl6010The ADL6010 versatile, broadband envelope detector covers the microwave spectrum, providing high accuracy and very low power consumption in a small package. The baseband output voltage is proportional to the instantaneous amplitude of the RF input, with an overall scaling factor of 2.2 from 0.5 GHz to 43.5 GHz. 11.2 mV to 1.8 V input voltages, which correspond to −30 dBm to +15 dBm input power relative to a 50-Ω source, generate quasi-dc outputs of about 25 mV to 4 V above common. The balanced detector topology does not create even-order distortion at the input, an important benefit in applications where a low ratio coupler is used to extract a signal. The power equivalent of a fluctuating RF input amplitude can be extracted by adding an rms-to-dc converter, or the baseband output can be applied to a suitably fast ADC, allowing the rms value and other signal metrics to be calculated in the digital domain. Operating on a 4.75-V to 5.25 V supply, the ADL6010 draws 1.6 mA. Available in 6-lead LFCSP packages, A-/S-versions are specified from 40C to +85C/55C to +125C and priced at $38.33/$66.12 in 1000s.

Technical Articles

Luis Orozco, How to Make Precision Light Measurements with Large Area Photodiodes, Anglia Live, 2014-07-28

Gustavo Castro, The Diamond Plot, Analog Dialogue, 2014-07-02

Gustavo Castro, The Diamond Plot, Planet Analog, 2014-06-30

Vicky Wong, Zero-crossover-distortion amplifiers improve linearity of DAC Systems, Power Systems Design, 2014-06-01

Mark Reisiger, Creative Compensation Enables Tiny Amplifier to Drive 200-mW Loads, Analog Dialogue, 2014-05-05

James Bryant, Discretion is the better part , Analog Dialogue, 2014-05-05

Qui Luu and Benjamin Sam, Differential Drive Optimizes Active Mixers, Microwaves&RF, 2014-04-11

James Bryant, Choosing Transistors, EDN, 2014-04-22

James Bryant, Current-Output Circuit Techniques Add Versatility to Your Analog Toolbox, Analog Dialogue, 2014-04-02

Chau Tran and Fotjana Bida, Difference Amplifiers Enable Low Loss, High-Performance Full-Wave Rectifier, Planet Analog, 2014-03-06

Harry Holt, A Deeper Look into Difference Amplifiers, Analog Dialogue, 2014-02-03

Rob Reeder, Designing for Wideband RF, EDN, 2014-01-28

Gustavo Castro and Scott Hunt, How to Stay Out of Deep Water when Designing with Bridge Sensors, Analog Dialogue, 2014-01-06

Kyle Slightom, Dual-Loop Clock Generator Cleans Jitter, Provides Multiple High-Frequency Outputs, Analog Dialogue, 2014-01-06

Sandro Herrera, Differential I/O low-power instrumentation amp, EDN, 2013-12-16

Rob Reeder, Analog Fundamentals: Amplifiers, EDN, 2013-10-06

Sandro Herrera, Measure Frequency Response on Fully Differential Amplifiers Using Complex Algebra, Design News, 2013-10-01

George Alexandrov and Nathan Carter, Some Tips on Making a FETching Discrete Amplifier, Analog Dialogue, 2013-10-01

Webinars and Tutorials

Developing Multiple-Input Multiple-Output (MIMO) Systems with the AD9361 - As software defined radio (SDR) and multiple-input multiple-output (MIMO) become more prevalent, there is a need for more channel diversity. This webcast will detail how to use multiple AD9361 RF agile transceivers to create an NN MIMO system, as well as explore the available tradeoffs in the design. The AD9361 is a fully integrated 22 MIMO transceiver. Its programmability and wideband capability make it ideal for a broad range of transceiver applications.

The Spectrum of Current Sensing: From DC to Light - Current measurement is an essential part of sensor interface, control, power management, and communications. The span of current sensing is from picoamperes to kiloamperes, and from dc to gigahertz (or light, when using photodiodes). We will cover high power and motor control, 420 mA industrial communications, energy monitoring, photodiodes, isolation, and developing precision current sources. We will also show on-line tools for circuit design.

Digital Filter Design for Integrated RF Transceivers - This webcast introduces how MATLAB from MathWorks can be used for complicated filter design in wireless SDR systems and components. We will create a model of the Analog Devices AD9361 and AD9364 RF transceivers, as integrated on the AD-FMCOMMS2-EBZ and AD-FMCOMMS4-EBZ SDR development platforms. We will use that model to design a filter for the internal FIR filters using the generated coefficients in an example system design.

Integrated Software-Defined Radio on Zynq-7000 All Programmable SoC -- This course introduces wireless communication system design on the new Avnet Zynq-7000 All Programmable SoC/AD9361 Software-Defined Radio Evaluation Kit featuring Analog Devices AD9361 single-chip RF agile transceiver. An IEEE 802.11 receiver example will demonstrate system-level simulation using MATLAB and Simulink modeling and code generation tools from MathWorks. Using the Xilinx Vivado Design Suite, the system will be implemented for production showing the receiver detecting 802.11 beacon frames in a stand-alone system running UBUNTU desktop Linux on Xilinx Zynq AP SoC. Presentations will alternate with instructor-led demos to illustrate coding techniques within MathWorks and Xilinx development tools for high-speed digital signal processing.

Introduction to Analog RMS-to-DC Technology: Converters and Applications This webinar provides users with a better understanding of the underlying theory of rms, and how rms-to-dc converters work.

The Fundamentals of Voltage References and Current Sensing - This webcast will discuss voltage references and how they are used in circuit design. It will also cover and compare reference designs, specifications, reference alternatives, and application ideas such as negative references, then present how currents are handled, measured, and generated in system design.

Precision basics: How not to be surprised by unexpected error sources - This webcast, co-sponsored by Avnet EM, presents error sources of a few fundamental front end signal conditioning blocks and provides hints for better practices that will save money and speed development time.

Fundamentals of Frequency Synthesis, Part 2: Direct Digital Synthesis (DDS) This concludes our two-part series on frequency synthesis with an introduction to direct digital synthesis. We will give a basic review of how a direct digital synthesis system works, touching on the inner workings of the DDS engine at a relatively high level. We will also discuss the tradeoffs between PLL and DDS technology as a base choice for frequency synthesis needs.

Fundamentals of Frequency Synthesis, Part 1: Phase Locked Loops The first of a two-part series on frequency synthesis, with an introduction to phase locked loops (PLLs). This webcast looks at the need for frequency generation; techniques from the past, present, and future; how to assess the performance of a frequency synthesizer; and real world applications. Particular attention will be focused on phase locked loops as frequency synthesizers.

Fundamentals of the RF Transmission and Reception of Digital Signals - Digital Modulation is an important topic for RF designers because most modern day transceivers transmit and receive digitally modulated data. In this webcast, part of ADI's continuing FUNDAMENTALS OF DESIGN series we will introduce you to the challengesand solutionsfor digital modulation. This webcast is a great way for beginners to get introduced to this vital communications standard or for veteran RF designers learn what's new in the field.


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