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Application Notes

AN-1310: Flash Programming via MDIOProtocol Type 8

This 4-page Application Note describes a protocol for programming the flash memory in the ADuMC320 precision analog microcontroller, which incorporates high performance analog and digital peripherals, an ARM Cortex-M3 processor, and flash memory. Its MDIO interface can operate at up to 4 MHz, simultaneously executing from one flash block and writing/erasing the other flash block.

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-1296: Optimizing Power Supplies for the AD9129

The evaluation board for the AD9129 14-bit, 5.6-GSPS RF digital-to-analog converter uses power supply filters to guarantee optimal performance. This 3-page Application Note explores the effects of removing most of the filter components. All ferrite beads on the board were removed, as well as the majority of the capacitors on the power supplies. Phase noise, noise spectral density (NSD), spurious-free dynamic range (SFDR), intermodulation distortion (IMD), and adjacent channel leakage ratio (ACLR) performance were all measured to demonstrate the effect of removing the filter components. The measurement results showed that the ferrite beads improved close-in phase noise at 20 Hz offset by approximately 5 dB, as well as single-tone IMD by up to 5 dB. Most of the capacitors proved to be redundant, however. The decoupling capacitors improved the ACLR for 6 MHz carriers by 5 dB; and the capacitor arrays improved the ACLR for 6 MHz carriers by approximately 6 dB and the NSD by approximately 1 dB. Removing all of the other the capacitors did not affect the performance.

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.

AN-1276: Embedded Packet Error Rate Testing on the ADF7023 and ADF7023-J

This 4-page Application Note provides information on the built-in packet error rate (PER) test mode on the ADF7023 and ADF7023-J. This mode helps the user to set up a communication link and test its quality. Up to 65,535 packets can be transmitted with a programmable delay between packets. The packet stored in packet RAM is transmitted each time. If the cyclic redundancy check (CRC) is correct, the receiver determines it has correctly received a packet.

AN-1275: Rolling Data Buffer on the ADF7023

When the ADF7023 receives a packet in packet mode, it stores the data in a linear sequence in the packet RAM. Prior to transmission, the data to be transmitted is written to the packet RAM in a linear sequence, as described in the ADF7023 data sheet. The ADF7023 packet RAM is 240 bytes long. If the packet length is greater than 240 bytes, additional measures are required. This 4-page Application Note describes a method for handling longer packet lengths on the ADF7023, up to a maximum length of 65,535 bytes, via a rolling buffer mechanism. This method reuses and renames several registers of the ADF7023.

AN-1268: Reference Design Using the ADF7241/ADF7242 and Skyworks SE2431L

This 11-page Application Note describes a reference design using the ADF7241/ADF7242 highly integrated, low power, high performance transceiver and the SE2431L fully integrated RF front-end. The ADF7241 and ADF7242, which operate in the global 2.4-GHz ISM band, provides flexibility, robustness, ease of use, and low current consumption. They support the IEEE 802.15.4-2006 2.4‑GHz PHY requirements. The ADF7242 also supports proprietary GFSK/FSK/GMSK/MSK modulation schemes in both packet and data streaming modes. The Skyworks SE2431L, designed for 2.4 GHz applications, provides ease of use and maximum flexibility, with fully matched 50 Ω input and output, integrated interstage matching, harmonic filter, and digital controls that are compatible with 1.6 V to 3.6 V CMOS levels.

AN-1258: Image Rejection Calibration on the ADF7021, ADF7021-N, and ADF7021-V

Heterodyne radios, such as the ADF7021 family of transceivers, use a mixer to down convert received RF signals to an intermediate frequency (IF). The output of the mixer contains the wanted frequency component along with an unwanted component at the image frequency. Unwanted signals present at the image frequency can degrade receiver sensitivity, resulting in loss of signal on the wanted channel. In theory, transceivers employing an I/Q receive architecture can be configured to infinitely reject the image frequency, assuming 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 digital control register until the quadrature signals are optimally balanced, providing maximum image rejection. This 11-page Application Note provides information on the mechanism that generates the image frequency and describes how image calibration can be implemented on the ADF7021, ADF7021-N, and ADF7021-V.

AN-1254: Synchronizing Multiple AD9915 DDS-Based Synthesizers

Various applications require the generation of two or more sinusoidal or square wave signals with a known phase relationship between them. The AD9915 DDS IC is capable of providing such signals. This 6-page Application Note offers detailed instructions on how to synchronize two or more of these devices and considers possible sources of phase error.

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.

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.

CN0311: Broadband, Low Error Vector Magnitude (EVM) Direct Conversion Transmitter Using LO Divide-by-2 Modulator

This broadband direct-conversion transmitter (analog baseband in, RF out) supports RF frequencies from 30 MHz to 2.2 GHz using a phase-locked loop (PLL) with an on-chip broadband voltage-controlled oscillator (VCO). Unlike modulators that use a divide-by-1 local oscillator (LO) stage, harmonic filtering of the LO is not required as long as the LO inputs to the modulator are driven differentially. The ADF4351 provides differential RF outputs and is, therefore, an excellent match. This PLL-to-modulator interface is useful for all I/Q modulators and I/Q demodulators that contain a 2XLO-based phase splitter.

CN0304: Low Power DDS Waveform Generator

This 75-MHz low-power (25 mW total) direct digital synthesis (DDS) waveform generator includes an output buffer and anti-imaging filter to provide improved spectral performance, making it suitable for frequency generation or clocking applications requiring sine wave, triangular wave, and square outputs up to 18 MHz. As sampled data devices, low-power DDS devices must be followed by a suitable anti-imaging filter to remove spectral images, but their maximum current output is approximately 4 mA into a recommended 200-Ω load, so an op amp buffer at the DDS output is required to provide a low-impedance drive source for a high-quality 50-Ω filter. The combination of the DDS, output buffer, and seventh-order elliptic low pass filter provides high-quality spectral performance.

CN0302: Ultra-Fast Settling PLL with RF to 13 GHz

This PLL circuit uses a 13-GHz fractional-N synthesizer, wideband active loop filter, and VCO, to achieve phase settling time of less than 5 μs to within 5 for a 200-MHz frequency jump. The performance is achieved using an active loop filter with 2.4-MHz bandwidth. This wideband loop filter is enabled by the 110-MHz maximum frequency of the ADF4159s phase-frequency detector (PFD); and the 145-MHz gain-bandwidth product of the AD8065 op amp. The AD8065 can operate on a 24 V supply voltage, allowing control of most wideband VCOs having tuning voltages from 0 V to 18 V.

CN0290: Extending the Low-Frequency Range of a High-Performance Phase Locked Loop

This high-performance phase locked loop (PLL) uses high-speed clock buffers and low-noise LDOs to maintain low phase noise even at low reference and RF frequencies. For example, the ADF4106 PLL specifies a 20-MHz minimum reference frequency and a 500-MHz minimum RF input frequency. This frequency range can be lowered to a 10-MHz reference frequency and a 100-MHz RF input frequency using additional clock buffers.

New Product Briefs

September 2014

24-bit, 250-kSPS Sigma-Delta ADC with 20-μs settling and rail-to-rail buffers

ad7175-2The AD7175-2 low-noise multiplexed Σ-Δ analog-to-digital converter accepts two fully differential or four pseudo-differential low-bandwidth inputs. The fast settling design has a maximum 50-kSPS channel scan rate and 5-SPS to 250-kSPS output data rates. The integrated analog- and digital signal conditioning blocks allow individual configuration for each input channel. True rail-to-rail buffers on the analog- and external reference inputs provide easy to drive high-impedance inputs. The precision 2.5-V low-drift (2 ppm/C) reference and reference buffer add functionality and reduce external component count. The digital filter allows simultaneous 50/60 Hz rejection at 27.27 SPS output data rate. The ADC automatically cycles through each selected channel. Further digital processing functions include offset and gain calibration. Operating with +5-V and 2.5-V supplies, the AD7175-2 dissipates 105 mW with buffers enabled, internal clock, and internal reference; 42 mW with buffers disabled, external clock, and external reference; 125 W in standby mode, and 25 W in power-down mode. Available in a 24-lead TSSOP package, it is specified from 40C to +105C and priced at $11.85 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

Quad, 16-bit, 2.8-GSPS, TxDAC+ Digital-to-Analog Converter

ad9144The AD9144 quad, 16-bit, 2.8-GSPS digital-to-analog converter (DAC) enables multicarrier generation up to the Nyquist frequency. The low-distortion design specifies 82-dBc spurious-free dynamic range (SFDR), 90‑dBc intermodulation distortion (IMD), and 162-dBm/Hz noise spectral density (NSD). The DAC outputs interface seamlessly with the ADRF672x analog quadrature modulators (AQMs). An optional 3- or 4-wire serial port interface (SPI) allows programming/readback of many internal parameters. The full-scale output current can be programmed over a typical range of 13.9 mA to 27.0 mA. The AD9144 operates on 1.2-V, 1.3-V, 1.8-V and 3.3-V supplies. Available in an 88-lead LFCSP package, it is specified from 40C to +85C and priced at $80.00 in 1000s.

Hot-Swap Controller with PMBus interface monitors energy and power

adm1278The ADM1278 hot-swap controller allows a circuit board to be removed from or inserted into a live backplane. The current-sense amplifier determines the load current by sensing the voltage across a resistor in the power path. The 12-bit ADC measures the load current, supply voltage, output voltage, and temperature at the external NPN device. The PMBus interface allows a controller to read data from the ADC. As many as 16 unique I2C addresses can be selected. The device features overvoltage (OV) and undervoltage (UV) protection, and a PWRGD signal that detects when the output supply is valid. Operating on a 4.5-V to 20-V supply, the ADM1278 draws 5.5 mA. Available in a 32-lead LFCSP package, it is specified from 40C to +85C and priced from $2.89 in 1000s.

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

Ian Beavers, Gigasample ADCs Promise Direct RF Conversion, Electronic Design, 2014-08-27

Rob Reeder, GSPS Converter Wideband Front-End Design, DigiKey, 2014-05-28

Ian Beavers, Understanding Spurious-Free Dynamic Range In Wideband GSPS ADCs, Electronic Design, 2014-05-12

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

Tom Gratzek, Product How-to: Sophisticated tools accelerate SDR exploration, EDN, 2014-04-08

Jarrett Liner, Understanding and designing wideband output networks for high speed D/A converters, EDN, 2014-03-19

Rob Reeder, Design Wideband Front Ends for GSPS Converters, Electronic Design, 2014-01-24

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

Duncan Bosworth, Multiband Analog Front End Brings One-Chip Radio Closer to Reality, Microwave Engineering Europe, 2013-12-02

Duncan Bosworth, Multiband Analogue Front End Brings One-Chip Radio Closer to Reality, EDN Europe, 2013-11-29

Jonathan Harris, Interleaving Spurs: Lets Look at the Math, Planet Analog, 2013-09-17

Ray Sun, How to Design and Debug a Phase-Locked Loop (PLL) Circuit, Analog Dialogue, 2013-09-04

Jonathan Harris, Interleaving Spurs: Bandwidth Mismatches, Planet Analog, 2013-08-29

Yi Zhang and Assaf Toledano, High-Speed DACs Fuel Multiband Transmitters, Microwaves & RF, 2013-08-22

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.

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.

Solving the Elusive Baseband to Antenna Problem using RFDAC Technology - This webinar will explore RF transmitter architectures, concentrating on the direct-to-RF architecture enabled by RFDAC technology. Aspects of the direct-to-RF transmitter system design will be explored including gain, signal bandwidth, digital signal processing requirements, frequency planning, thermal noise, clock synthesis + phase noise, harmonics, sampling images, pre-distortion techniques, and deterministic latency.

The Evolving Architecture of Military Communication Systems -- This webcast explores the different bands of Military Communications, and the advantages and disadvantages of each. We talk briefly about the shift toward software defined radios (SDR) and what that means for todays system designers. We talk about traditional Tx/Rx signal chains for these radios, where they are heading in the future, and the key analog and mixed-signal technology that is driving these changes.

Fundamentals of Data Conversion in Receivers - This webinar examines a contemporary receive signal chain and takes a close look at selecting suitable data converters, their key specifications, and the tradeoffs that must be made.

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.


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