ADL5385ACPZ High-performance Broadband I/Q Orthogonal Modulator - IF / RF Digital Communication Solution

ADL5385ACPZ is a silicon-based single-chip integrated quadrature modulator packaged as QFN-24-EP (4x4). It is manufactured using Analog Devices, Inc.'s advanced silicon germanium (SiGe) bipolar process. Its performance specifications cover a working temperature range of -40°C to +85°C, and it also provides an evaluation board that complies with RoHS standards.

Notes：The suffix "ACPZ" refers to the specific package and lead finish offered by Analog Devices.Variants like ADL5385ACPZ-R7 are the same IC supplied in tape & reel for automated placement.

Introducing ADL5385ACPZ

Features

• Output frequency range: 30 MHz to 2200 MHz
• 1 dB output compression: 11 dBm at 350 MHz
• Noise floor: –159 dBm/Hz at 350 MHz
• Sideband suppression: −50 dBc at 350 MHz
• Carrier feedthrough: −46 dBm at 350 MHz
• Single supply: 4.75 V to 5.5 V
• 24-lead, RoHS-compliant, LFCSP with exposed pad

Absolute maximum ratings

Pin configuration

Circuit composition and description

The ADL5385ACPZ can be divided into five sections: the localoscillator (LO) interface, the baseband voltage-to-current (V-to-I)converter, the mixers, the differential-to-single-ended (D-to-S)amplifier, and the bias circuit.

1. LO interface
Buffers and down-converts the external local oscillator signal, generating two half-frequency, orthogonal carriers for driving the mixer.
2. V-I converter
Converts the differential baseband input voltage into an current signal, providing drive for the subsequent mixer modulation stage.
3. Mixer
Uses a Gilbert structure for a dual-balanced mixer to modulate and combine the I/Q carriers.
4. Differential-to-single-ended amplifier
Converts the mixed differential signal to a single-ended output and provides an appropriate output impedance to drive the load.
5. Bias circuit
The bandgap reference generates stable bias current. ENBL controls the power-on of the device. The TEMP pin outputs a temperature-dependent voltage for monitoring or compensation.

Using ADL5385ACPZ

Working Principle

1. The external local oscillator signal enters the chip and undergoes buffering and division-by-two processing, generating two quadrature carriers with a frequency half of LO and a phase difference of 90°, which are used as the modulation carriers for the I channel and Q channel respectively. At the same time, the I and Q signals from the differential baseband input are converted into current signals proportional to the input amplitude by a voltage-to-current converter.
2. The I and Q currents are sent to the dual-balanced mixer (Gilbert structure) respectively, and multiplied with the corresponding quadrature carriers for modulation, resulting in the modulated I and Q signals.
3. The two modulated signals are synthesized in the load and output as a differential to single-ended amplifier as a single-ended RF signal, which can directly drive a 50 Ω load. The internal bandgap bias circuit provides stable working current for each module and supports enable control and temperature monitoring.

Application example

1. Radio-link infrastructure
Method: As the IF or direct conversion RF quadrature modulator at the transmitting end, it upconverts the baseband I/Q signals (such as QPSK, QAM, etc.) to the microwave or radio frequency band, and is commonly used for point-to-point microwave backhaul and private network wireless links.
2.Cable modem termination systems
Method: In the downlink, it modulates the digital baseband signal onto the RF carrier (from tens of MHz to GHz), and uses it to generate high-quality QAM signals for transmission into the coaxial network.
3.UHF/VHF radio
Method: As an IF → RF modulator, it modulates the digital or analog I/Q signals onto the VHF/UHF band, and is applied to professional radio, broadcasting or dedicated communication.
4.Wireless infrastructure systems
Used for the transmitting link of base stations or small base stations, digital baseband → ADL5385 → RF amplifier → antenna, supporting IF architecture or Zero-IF architecture.
5. Wireless local loop
Method: In the access side transmitting unit, it modulates the broadband I/Q signal onto the radio frequency, supporting point-to-multipoint wireless access systems.
6.WiMAX/broadband wireless access systems
Method: As the core modulator of the digital modulation transmission link, it supports complex modulation methods such as OFDM/QAM, and is usually combined with high-speed DAC + PA to form a complete transmission link.
Notes: ADL5385 is typically located in the wireless transmission link and performs the orthogonal modulation function of "I/Q baseband → IF/RF radio frequency signal", and is suitable for communication systems with high requirements for linearity, phase accuracy and wideband performance.

Common FAQs for ADL5385ACPZ

OK. ADL5385 supports IF architecture and Zero-IF (Direct RF) architecture, depending on the LO frequency configuration.
Q2: What modulation methods are supported?
It supports common digital modulation methods such as QPSK, 16/64/256QAM, OFDM, etc., which are suitable for broadband communication systems.
Q3: What is the supply voltage and temperature range?

• Supply voltage: approximately 5 V
• Operating temperature range: –40°C to +85°C