Features and Benefits
- DPD receiver with integrated fractional-N PLL
- RF input frequency range: 450 MHz to 2800 MHz
- Internal LO input frequency range: 450 MHz to 2800 MHz
- Dual RF inputs with SPDT absorptive RF switches
- Integrated RF balun for single-ended 50 Ω input
- Integrated VCO to cover complete RF input range
- Digital programmable LO phase offset and dc nulling
- Programmable via 4-wire SPI
- 56-lead, 8 mm × 8 mm LFCSP
The ADRF6821 is a highly integrated, dual radio frequency (RF) input, zero intermediate frequency (IF)/low IF RFIC receiver with a quadrature demodulator, digital step attenuator (DSA), IF linear amplifiers, an integrated, fractional-N phase-locked loop (PLL), and a low phase noise, multicore, voltage controlled oscillator (VCO). The RFIC is ideally suited for communication digital predistortion (DPD) systems.
The high isolation 2:1 RF switch and on-chip wideband RF balun enable the ADRF6821 to support two single-ended, 50 Ω terminated RF inputs. A programmable attenuator ensures an optimal differential RF input level to the high linearity demodulator core. The integrated attenuator offers an attenuation range of 15 dB with a step size of 1 dB. High linearity IF amplifiers follow the demodulator and provide an interface to the next component in the chain, typically an analog-to-digital converter (ADC).
The ADRF6821 offers two alternatives for generating the differential local oscillator (LO) input signal: internally via the on-chip fractional-N synthesizer with low phase noise VCOs or externally via a low phase noise LO signal. The integrated synthesizer enables continuous LO coverage from 450 MHz to 2800 MHz. The PLL reference input supports a wide frequency range and includes integrated reference dividers before the phase frequency detector (PFD).
When selected, the output of the internal fractional-N synthesizer is applied to a divide by 2, quadrature phase splitter. From the external LO path, a 2× LO signal can be used with the divide by 2, quadrature phase splitter to generate the quadrature LO inputs to the mixers.
The ADRF6821 is fabricated using an advanced silicon germanium (SiGe), bipolar complementary metal oxide semiconductor (BiCMOS) process. It is available in a 56-lead, RoHS compliant, 8 mm × 8 mm LFCSP package with an exposed pad. Performance is specified over the −40°C to +105°C case temperature range.
- Cellular W-CDMA/GSM/LTE
- DPD receivers
- Microwave, point to point radios
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
The ADRF6821-EVALZ evaluates the performance of the ADRF6821. The evaluation board contains the ADRF6821, a connector suited for the SDP-S controller board, power supply connectors, regulators, and subminiature Version A (SMA) connectors. The ADRF6821-EVALZ requires an SDP-S controller board to program the ADRF6821. The ADRF6821-EVALZ is a 4-layer Rogers printed circuit board (PCB).
The ADRF6821 is a high performance, wideband demodulator solution that supports input radio frequencies (RF) ranging from 450 MHz to 2800 MHz. Highly integrated, the device consists of a 2:1 input RF switch; integrated RF balun; quadrature demodulator, integrated phase-locked loop (PLL)/voltage controlled oscillator (VCO); and integrated intermediate frequency (IF) amplifiers and analog-to-digital (ADC) drivers. The device supports input/output bandwidths up to 500 MHz and includes 15 dB of programmable attenuation. The integrated PLL/VCO within the ADRF6821 provides a 2× local oscillator (LO) signal for a range of 900 MHz to 5600 MHz.
The ADRF6821 data sheet provides additional information and should be consulted when using the evaluation board.
Tools & Simulations
ADIsimPLL enables the rapid and reliable evaluation of new high performance PLL products from ADI. It is the most comprehensive PLL Synthesizer design and simulation tool available today. Simulations performed include all key non-linear effects that are significant in affecting PLL performance. ADIsimPLL removes at least one iteration from the design process, thereby speeding the design- to-market.
ADIsimRF is an easy-to-use RF signal chain calculator. Cascaded gain, noise, distortion and power consumption can be calculated, plotted and exported for signal chains with up to 50 stages. ADIsimRF also includes an extensive data base of device models for ADI’s RF and mixed signal components.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.