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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs

ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs
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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs

Product catalog summary
Overview
The ADRF6720 is a high-performance broadband I/Q modulator with an integrated fractional-N PLL and multicore VCOs. It supports RF output frequencies from 700 MHz to 3000 MHz and is programmable via an SPI interface. The device is suitable for various applications including broadband communication systems and military/aerospace uses.
Features
The ADRF6720 offers a wideband quadrature modulator with key performance metrics such as an output P1dB of 12.2 dBm at 2140 MHz, output IP3 of 32.6 dBm, and sideband suppression of -37.6 dBc. It operates with a 3.3 V power supply and has a baseband modulation bandwidth greater than 1000 MHz.
Specifications
The device operates over a temperature range of -40°C to +85°C, with a noise floor of -157.9 dBm/Hz at 2140 MHz. It supports high-side/low-side LO injection and is programmable via a 3-wire SPI. The supply voltage range is 3.3 V, with specific current requirements for different modes.
Performance Characteristics
Typical performance includes an output power of 5 dBm at 2140 MHz and a modulator voltage gain of 1.12 dB. The synthesizer specifications include a figure of merit (FOM) of -218.5 dBc/Hz/Hz.
Applications Information
Guidance is provided for DAC-to-I/Q modulator interfacing, baseband bandwidth considerations, and optimization techniques for carrier feedthrough and sideband suppression.
Layout and Design Considerations
Recommendations include power supply, grounding, and layout to ensure optimal performance. The device should be soldered to a low thermal and electrical impedance ground plane.
LO Generation and Modes
The ADRF6720 supports both internal and external LO signals. The internal LO is generated by an on-chip VCO tunable from 2850 MHz to 5710 MHz. In external LO mode, it accepts differential LO signals from 700 MHz to 3 GHz.
PLL and Frequency Programming
The PLL includes a reference path, phase and frequency detector, charge pump, and a programmable integer divider. Equations are provided for determining the N value and PLL frequency.
Baseband and Active Mixers
The baseband inputs have a 500 Ω differential impedance. The device features two double balanced mixers for the I and Q channels, which upconvert modulated baseband signal currents to RF using LO signals.
Enable/Disable Functionality
The ENBL pin allows quick enabling/disabling of the RF output, with control over internal blocks via the enables register.
Register Map and Details
The document includes a comprehensive register map detailing various settings and configurations for the ADRF6720, such as SOFT_RESET, ENABLES, INT_DIV, FRAC_DIV, MOD_DIV, and others.
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Catalog excerpts

ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-1

Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs ADRF6720 Data Sheet FEATURES GENERAL DESCRIPTION I/Q modulator with integrated fractional-N PLL RF output frequency range: 700 MHz to 3000 MHz Internal LO frequency range: 356.25 MHz to 2855 MHz Output P1dB: 12.2 dBm at 2140 MHz Output IP3: 32.6 dBm at 2140 MHz Carrier feedthrough: −40.3 dBm at 2140 MHz Sideband suppression: −37.6 dBc at 2140 MHz Noise floor: −157.9 dBm/Hz at 2140 MHz Baseband 1 dB modulation bandwidth: >1000 MHz Baseband input bias level: 0.5 V Power supply: 3.3 V/425 mA Integrated RF tunable balun allowing single-ended RF output Multicore integrated VCOs HD3/IP3 optimization Sideband suppression and carrier feedthrough optimization High-side/low-side LO injection Programmable via 3-wire serial port interface (SPI) 40-lead 6 mm × 6 mm LFCSP The ADRF6720 is a wideband quadrature modulator with an integrated synthesizer ideally suited for 3G and 4G communication systems. The ADRF6720 consists of a high linearity broadband modulator, an integrated fractional-N phase-locked loop (PLL), and four low phase noise multicore voltage controlled oscillators (VCOs). The ADRF6720 local oscillator (LO) signal can be generated internally via the on-chip integer-N and fractional-N synthesizers, or externally via a high frequency, low phase noise LO signal. The internal integrated synthesizer enables LO coverage from 356.25 MHz to 2855 MHz using the multicore VCOs. In the case of internal LO generation or external LO input, quadrature signals are generated with a divide-by-2 phase splitter. When the ADRF6720 is operated with an external 1 × LO input, a polyphase filter generates the quadrature inputs to the mixer. The ADRF6720 offers digital programmability for carrier feedthrough optimization, sideband suppression, HD3/IP3 optimization, and high-side or low-side LO injection. APPLICATIONS 2G/3G/4G/LTE broadband communication systems Microwave point-to-point radios Satellite modems Military/aerospace Instrumentation The ADRF6720 is fabricated using an advanced silicongermanium BiCMOS process. It is available in a 40-lead, RoHS-compliant, 6 mm × 6 mm LFCSP package with an exposed pad. Performance is specified over the −40°C to +85°C temperature range. FUNCTIONAL BLOCK DIAGRAM VPOSx 40 LOOUT+ LOOUT– PHASE CORRECTION PHASE CORRECTION SERIAL PORT INTERFACE 31 Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 ©2014 Analog Devices, Inc. All rights reserved. Technical Support

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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-2

Data Sheet REVISION HISTORY 4/14—Revision 0: Initial Version

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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-3

Data Sheet SPECIFICATIONS VPOSx = 3.3 V, TA = 25°C; baseband I/Q amplitude = 1 V p-p differential sine waves in quadrature with a 500 mV dc bias, unless otherwise noted. Table 1. Parameter OPERATING FREQUENCY RANGE Output IP3 Noise Floor RF OUTPUT = 1900 MHz Output Power, POUT Modulator Voltage Gain Output P1dB Carrier Feedthrough Sideband Suppression Quadrature Error I/Q Amplitude Balance Second Harmonic Third Harmonic Output IP2 Output IP3 Noise Floor RF OUTPUT = 2140 MHz Output Power, POUT Modulator Voltage Gain Output P1dB Carrier Feedthrough Sideband Suppression Quadrature Error I/Q Amplitude...

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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-4

ADRF6720 Parameter Output IP2 Output IP3 Noise Floor RF OUTPUT = 2300 MHz Output Power, POUT Modulator Voltage Gain Output P1dB Carrier Feedthrough Sideband Suppression Quadrature Error I/Q Amplitude Balance Second Harmonic Third Harmonic Output IP2 Output IP3 Noise Floor RF OUTPUT = 2600 MHz Output Power, POUT Modulator Voltage Gain Output P1dB Carrier Feedthrough Sideband Suppression Quadrature Error I/Q Amplitude Balance Second Harmonic Third Harmonic Output IP2 Output IP3 Noise Floor SYNTHESIZER SPECIFICATIONS Figure of Merit (FOM)1 REFERENCE CHARACTERISTICS REFIN Input Frequency REFIN Input...

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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-5

Data Sheet Parameter MUXOUT Output Level MUXOUT Duty Cycle CHARGE PUMP Charge Pump Current Output Compliance Range PHASE NOISE, FREQUENCY = 940 MHz, fPFD = 38.4 MHz Integrated Phase Noise Reference Spurs PHASE NOISE, FREQUENCY = 1900 MHz, fPFD = 38.4 MHz Integrated Phase Noise Reference Spurs PHASE NOISE, FREQUENCY = 2140 MHz, fPFD = 38.4 MHz Integrated Phase Noise Reference Spurs ADRF6720 Test Conditions/Comments Low (lock detect output selected) High (lock detect output selected) Closed-loop operation (20 kHz loop filter, see Figure 44 for loop filter design) 10 kHz offset 100 kHz offset 1...

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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-6

ADRF6720 Parameter PHASE NOISE, FREQUENCY = 2300 MHz, fPFD = 38.4 MHz Integrated Phase Noise Reference Spurs PHASE NOISE, FREQUENCY = 2600 MHz, fPFD = 38.4 MHz Integrated Phase Noise Reference Spurs LO INPUT/OUTPUT LO Output Frequency Range LO Output Level LO Input Level LO Input Impedance BASEBAND INPUTS I and Q Input DC Bias Level Bandwidth Differential Input Impedance Differential Input Capacitance OUT ENABLE Turn-On Settling Time Turn-Off Settling Time Data Sheet Test Conditions/Comments Closed-loop operation (20 kHz loop filter, see Figure 44 for loop filter design) 10 kHz offset 100 kHz...

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ADRF6720: Wideband Quadrature Modulator with Integrated Fractional-N PLL and VCOs-7

Data Sheet Parameter DIGITAL LOGIC Input Voltage High (VIH) Input Voltage Low (VIL) Input Current (IIH/IIL) Input Capacitance (CIN) Output Voltage High (VOH) Output Voltage Low (VOL) POWER SUPPLIES Voltage Range Supply Current Test Conditions/Comments SCLK, SDIO, CS, and ENBL VPOSx Tx mode at internal LO mode (PLL, internal VCO , and modulator enabled, LO output driver disabled) Tx mode at external 1× LO mode (PLL, internal VCO disabled, modulator enabled, LO output driver disabled) LO output driver; LO_DRV_LVL bits (Register 0x22[7:6]) = 10 Power-down mode The figure of merit (FOM) is computed...

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