Software Defined Radio (SDR)

The AD9361 is a high performance, highly integrated radio frequency (RF) Agile Transceiver™ designed for use in 3G and 4G base station applications. Its programmability and wideband capability make it ideal for a broad range of transceiver applications. The device combines a RF front end with a flexible mixed-signal baseband section and integrated frequency synthesizers, simplifying design-in by providing a configurable digital interface to a processor. The AD9361 receiver LO operates from 70 MHz to 6.0 GHz and the transmitter LO operates from 47 MHz to 6.0 GHz range, covering most licensed and unlicensed bands. Channel bandwidths from less than 200 kHz to 56 MHz are supported.

The two independent direct conversion receivers have state-of-the-art noise figure and linearity. Each receive (RX) subsystem includes independent automatic gain control (AGC), dc offset correction, quadrature correction, and digital filtering, thereby eliminating the need for these functions in the digital baseband. The AD9361 also has flexible manual gain modes that can be externally controlled. Two high dynamic range analog-to-digital converters (ADCs) per channel digitize the received I and Q signals and pass them through configurable decimation filters and 128-tap finite impulse response (FIR) filters to produce a 12-bit output signal at the appropriate sample rate.

The transmitters use a direct conversion architecture that achieves high modulation accuracy with ultralow noise. This transmitter design produces a best in class TX error vector magnitude (EVM) of <−40 dB, allowing significant system margin for the external power amplifier (PA) selection. The on-board transmit (TX) power monitor can be used as a power detector, enabling highly accurate TX power measurements.

The fully integrated phase-locked loops (PLLs) provide low power fractional-N frequency synthesis for all receive and transmit channels. Channel isolation, demanded by frequency division duplex (FDD) systems, is integrated into the design. All VCO and loop filter components are integrated. The core of the AD9361 can be powered directly from a 1.3 V regulator. The IC is controlled via a standard 4-wire serial port and four real-time input/output control pins. Comprehensive power-down modes are included to minimize power consumption during normal use. The AD9361 is packaged in a 10 mm × 10 mm, 144-ball chip scale package ball grid array (CSP_BGA).

Applications

• Point to point communication systems
• Femtocell/picocell/microcell base stations
• General-purpose radio systems

The AD9364 is a 1 x 1 channel high performance, highly integrated RF Agile Transceiver™. Its programmability and wideband capability make it ideal for a broad range of transceiver applications. The device combines an RF front end with a flexible mixed-signal baseband section and integrated frequency synthesizers, simplifying design-in by providing a configurable digital interface to a processor. The AD9364 operates in the 70 MHz to 6.0 GHz range, covering most licensed and unlicensed bands. Channel bandwidths from less than 200 kHz to 56 MHz are supported.

The AD9364 is packaged in a 10 mm × 10 mm, 144-ball chip scale package ball grid array (CSP_BGA).

Applications

• Point to point communication systems
• Femtocell/picocell/microcell base stations
• General-purpose radio systems

The AD9371 is a highly integrated, wideband RF transceiver offering dual channel transmitters and receivers, integrated synthesizers, and digital signal processing functions. The IC delivers a versatile combination of high performance and low power consumption required by 3G/4G micro and macro BTS equipment in both FDD and TDD applications. The AD9371 operates from 300 MHz to 6000 MHz, covering most of the licensed and unlicensed cellular bands. The IC supports receiver bandwidths up to 100 MHz. It also supports observation receiver and transmit synthesis bandwidths up to 250 MHz to accommodate digital correction algorithms.

The transceiver consists of wideband direct conversion signal paths with state-of-the-art noise figure and linearity. Each complete receiver and transmitter subsystem includes dc offset correction, quadrature error correction (QEC), and programmable digital filters, eliminating the need for these functions in the digital baseband. Several auxiliary functions such as an auxiliary analog- to-digital converter (ADC), auxiliary digital-to-analog converters (DACs), and general-purpose input/outputs (GPIOs) are integrated to provide additional monitoring and control capability.

An observation receiver channel with two inputs is included to monitor each transmitter output and implement interference mitigation and calibration applications. This channel also connects to three sniffer receiver inputs that can monitor radio activity in different bands.

The high speed JESD204B interface supports lane rates up to 6144 Mbps. Four lanes are dedicated to the transmitters and four lanes are dedicated to the receiver and observation receiver channels.

The fully integrated phase-locked loops (PLLs) provide high performance, low power fractional-N frequency synthesis for the transmitter, the receiver, the observation receiver, and the clock sections. Careful design and layout techniques provide the isolation demanded in high performance base station applications. All voltage controlled oscillator (VCO) and loop filter components are integrated to minimize the external component count.

A 1.3 V supply is required to power the core of the AD9371, and a standard 4-wire serial port controls it. Other voltage supplies provide proper digital interface levels and optimize transmitter and auxiliary converter performance. The AD9371 is packaged in a 12 mm × 12 mm, 196-ball chip scale ball grid array (CSP_BGA).

Applications

• 3G/4G micro and macro base stations (BTS)
• 3G/4G multicarrier picocells 
• FDD and TDD active antenna systems 
• Microwave, nonline of sight (NLOS) backhaul systems

The AD9680 is a dual, 14-bit, 1.25 GSPS/1 GSPS/820 MSPS/500 MSPS analog-to-digital converter (ADC). The device has an on-chip buffer and sample-and-hold circuit designed for low power, small size, and ease of use. This device is designed for sampling wide bandwidth analog signals of up to 2 GHz. The AD9680 is optimized for wide input bandwidth, high sampling rate, excellent linearity, and low power in a small package.

The dual ADC cores feature a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC features wide bandwidth inputs supporting a variety of user-selectable input ranges. An integrated voltage reference eases design considerations.

The analog input and clock signals are differential inputs. Each ADC data output is internally connected to two digital down-converters (DDCs). Each DDC consists of up to five cascaded signal processing stages: a 12-bit frequency translator (NCO), and four half-band decimation filters. The DDCs are bypassed by default.

In addition to the DDC blocks, the AD9680 has several functions that simplify the automatic gain control (AGC) function in the communications receiver. The programmable threshold detector allows monitoring of the incoming signal power using the fast detect output bits of the ADC. If the input signal level exceeds the programmable threshold, the fast detect indicator goes high. Because this threshold indicator has low latency, the user can quickly turn down the system gain to avoid an overrange condition at the ADC input.

Users can configure the Subclass 1 JESD204B-based high speed serialized output in a variety of one-, two-, or four-lane configurations, depending on the DDC configuration and the acceptable lane rate of the receiving logic device. Multiple device synchronization is supported through the SYSREF± and SYNCINB± input pins.

The AD9680 has flexible power-down options that allow significant power savings when desired. All of these features can be programmed using a 1.8 V to 3.3 V capable, 3-wire SPI.

The AD9680 is available in a Pb-free, 64-lead LFCSP and is specified over the −40°C to +85°C industrial temperature range. This product is protected by a U.S. patent.

Product Highlights

1. Wide full power bandwidth supports IF sampling of signals up to 2 GHz.
2. Buffered inputs with programmable input termination eases filter design and implementation.
3. Four integrated wideband decimation filters and numerically controlled oscillator (NCO) blocks supporting multiband receivers.
4. Flexible serial port interface (SPI) controls various product features and functions to meet specific system requirements.
5. Programmable fast overrange detection.
6. 9 mm × 9 mm, 64-lead LFCSP.

Applications

• Communications
• Diversity multiband, multimode digital receivers
  • 3G/4G, TD-SCDMA, W-CDMA, GSM, LTE
• General-purpose software radios
• Ultrawideband satellite receivers
• Instrumentation
• Radars
• Signals intelligence (SIGINT)
• DOCSIS 3.0 CMTS upstream receive paths
• HFC digital reverse path receivers

The circuit shown in Figure 1 is an RF power measurement circuit that accurately measures the power from an RF signal source within a frequency range of 9 kHz to 6 GHz, and has a nominal input power range of 45 dBm (−30 dBm to +15 dBm).

This circuit constitutes a complete rms RF power meter in a tiny form factor that can be powered entirely from a 5 V USB power supply. The measurement signal chain consists of an rms responding RF power detector and a 12-bit, precision analog-to-digital converter (ADC). These devices are powered by a CMOS linear regulator which generates 3.3 V from the 5 V USB supply.

A simple calibration routine can be performed at multiple frequencies to compensate for any frequency response variation of the circuit. Calibration data is stored in a lookup table, which is referenced during the RF power measurement.

The circuit block diagram shown in Figure 1 is a low phase noise translation loop synthesizer (also known as an offset loop). This circuit translates the lower 100 MHz reference frequency of the ADF4002 phase locked loop (PLL) up to a higher frequency range of 5.0 GHz to 5.4 GHz, as determined by the frequency of the local oscillator (LO).

The translation loop synthesizer has very low phase noise (<50 fs) in contrast to a synthesizer using only a PLL. The low phase noise is because of the very low N value used by the ADF4002 integer-N PLL, which controls the voltage controlled oscillator (VCO). In this example, the ADF4002 phase frequency detector (PFD) runs at 100 MHz, and N = 1, yielding phase noise performance that is not limited by the N value of the PLL.