EVAL-ADF7020DBZ2 datasheet(4/48 Pages) AD

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ADF7020

Data Sheet

Rev. D | Page 4 of 48

GENERAL DESCRIPTION

The ADF7020 is a low power, highly integrated FSK/ASK/OOK

transceiver designed for operation in the license-free ISM bands

at 433 MHz, 868 MHz, and 915 MHz, as well as the proposed

Japanese RFID band at 950 MHz. A Gaussian data filter option

is available to allow either GFSK or G-ASK modulation, which

provides a more spectrally efficient modulation. In addition to

these modulation options, the ADF7020 can also be used to

perform both MSK and GMSK modulation, where MSK is a

special case of FSK with a modulation index of 0.5. The modula-

tion index is calculated as twice the deviation divided by the

data rate. MSK is spectrally equivalent to O-QPSK modulation

with half-sinusoidal Tx baseband shaping, so the ADF7020 can

also support this modulation option by setting up the device in

MSK mode.

This device is suitable for circuit applications that meet the

European ETSI-300-220, the North American FCC (Part 15),

or the Chinese Short Range Device regulatory standards. A

complete transceiver can be built using a small number of

external discrete components, making the ADF7020 very

suitable for price-sensitive and area-sensitive applications.

The transmitter block on the ADF7020 contains a VCO and

low noise fractional-N PLL with an output resolution of

<1 ppm. This frequency agile PLL allows the ADF7020 to be

used in frequency-hopping spread spectrum (FHSS) systems.

The VCO operates at twice the fundamental frequency to

reduce spurious emissions and frequency-pulling problems.

The transmitter output power is programmable in 0.3 dB steps

from −16 dBm to +13 dBm. 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 (200 kHz),

minimizing power consumption and the external component

count and avoiding interference problems at low frequencies.

The ADF7020 supports a wide variety of programmable

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 patent-pending automatic frequency

control (AFC) loop, allowing the PLL to track out the frequency

error in the incoming signal.

An on-chip ADC provides readback of an integrated tempera-

ture sensor, an external analog input, the battery voltage, or the

RSSI signal, which provides savings on an ADC in some appli-

cations. 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 doing a 1-point calibration at

room temperature and storing the result in memory.

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