ADF7021-V 데이터 시트보기 (PDF) - Analog Devices

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ADF7021-V

High Performance, Narrow-Band Transceiver IC

Analog Devices 

GENERAL DESCRIPTION

The ADF7021-V is a high performance, low power, narrow-band

RF transceiver based on the ADF7021-N. The architecture of

the ADF7021-V transceiver is similar to that of the ADF7021-N

except that an external VCO is used by the on-chip RF synthesizer

for applications that require improved phase noise performance.

The ADF7021-V is designed to operate in both the license-free

ISM bands and in the licensed bands from 80 MHz to 960 MHz.

To minimize RF feedthrough and spurious emissions, the

external VCO operates at 2× or 4× the desired RF frequency;

the ADF7021-V supports a maximum VCO frequency operation

of 1920 MHz. The 4× VCO operation is programmable by

enabling an additional on-chip divide-by-2 outside the RF

synthesizer loop and offers improved phase noise performance.

As with the ADF7021-N receiver, the IF filter bandwidths

of 9 kHz, 13.5 kHz, and 18.5 kHz are supported, making the

ADF7021-V ideally suited to worldwide narrow-band telemetry

applications.

The part has both Gaussian and raised cosine transmit data

filtering options to improve spectral efficiency for narrow-band

applications. It is suitable for circuit applications targeted at the

following:

• European ETSI EN 300 220

• North American FCC Part 15, Part 90, and Part 95

• Japanese ARIB STD-T67

• Korean short-range device regulations

• Chinese short-range device regulations

A complete transceiver can be built using a small number of

discrete external components, making the ADF7021-V very

suitable for area-sensitive, high performance driven applications.

The range of on-chip FSK modulation and data filtering options

allows users greater flexibility in their choice of modulation

schemes while meeting the tight spectral efficiency requirements.

The ADF7021-V also supports protocols that dynamically switch

among 2FSK, 3FSK, and 4FSK to maximize communication

range and data throughput.

ADF7021-V

The transmit section contains a low noise fractional-N PLL with

an output resolution of <1 ppm. The frequency-agile PLL allows

the ADF7021-V to be used in frequency-hopping spread spectrum

(FHSS) systems. The VCO is external, which provides better

phase noise and thus lower adjacent channel power (ACP) and

adjacent channel rejection (ACR) compared with the ADF7021-N.

The VCO tuning range extends from 0.2 V to 2 V, which should

be taken into account when choosing the external VCO.

The transmitter output power is programmable in 63 steps from

−16 dBm to +13 dBm and has an automatic power amplifier ramp

control to prevent spectral splatter and help meet regulatory

standards. The transceiver RF frequency, channel spacing, and

modulation are programmable using a simple 3-wire interface.

The device operates with a power supply range of 2.3 V to 3.6 V

and can be powered down when not in use.

A low IF architecture is used in the receiver (100 kHz), which

minimizes power consumption and the external component

count yet avoids dc offset and flicker noise at low frequencies.

The IF filter has programmable bandwidths of 9 kHz, 13.5 kHz,

and 18.5 kHz. The ADF7021-V supports a wide variety of pro-

grammable features, including Rx linearity, sensitivity, and IF

bandwidth, allowing the user to trade off receiver sensitivity

and selectivity against current consumption, depending on

the application. The receiver also features a patented automatic

frequency control (AFC) loop with programmable pull-in range

that allows the PLL to remove the frequency error in the

incoming signal.

The receiver achieves an image rejection performance of 50 dB

using a patent-pending IR calibration scheme that does not

require the use of an external RF source.

An on-chip ADC provides readback of the integrated temper-

ature sensor, external analog input, battery voltage, and RSSI

signal, which can eliminate the need for an external ADC in

some applications. The temperature sensor is accurate to ±10°C

over the full operating temperature range of −40°C to +85°C.

This accuracy can be improved by performing a one-point cali-

bration at room temperature and storing the result in memory.

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