1GHz bandwidth and 60dB image rejection, supporting 300MHz to 9GHz I/Q

Analog Devices, Inc. announced the introduction of the LTC5594, a new wideband, high linearity zero-IF (ZIF) demodulator supporting 1GHz of I/Q 1dB bandwidth.

The new product typically delivers image rejection performance of 37 dB. Using the on-chip serial port, phase and amplitude imbalances of I and Q signals can be corrected, allowing image rejection performance to be adjusted to over 60 dB.

These features ease calibration, improve receiver performance, and reduce FPGA resources required for ghosting. The device integrates a gain-adjustable baseband amplifier, providing 9.2 dB of peak power conversion gain at 5.8 GHz and 37 dBm output IP3 (OIP3). The RF input integrates a wideband balun transformer, enabling single-ended operation with 50 Ω matching from 500 MHz to 9 GHz. By changing the value of one external matching component, the same input can be matched at lower frequencies between 300 MHz and 500 MHz. The new product's high level of integration minimizes the use of external components and reduces solution size.



The on-chip serial port allows optimization of various linearity performances, including image rejection, 2nd order intercept (IP2), 2nd order harmonic distortion (HD2), 3rd order harmonic distortion (HD3), and IIP3. The output DC offset voltage can be nulled through the serial port to enable DC coupling to the ADC for true zero-IF operation. After calibration at room temperature, these performance metrics exhibit excellent stability at both low and high temperatures, ranging from -40°C to 105°C.

The LTC5594 is ideal for 5G microwave wireless infrastructure platforms that require bandwidths exceeding 1GHz and dynamic range to support high-order modulation and gigabit data rates. It also offers numerous advantages in other applications, including wideband microwave point-to-point backhaul, high-performance GPS systems, satellite communications, avionics, RF test equipment, and radar systems. The device's exceptional linearity and image rejection performance are particularly useful in digital pre-distortion (DPD) receiver applications.

The LTC5594 is housed in a 32-pin 5mm x 5mm plastic QFN package. The demodulator operates from a single 5V supply and draws 470mA. The baseband amplifiers can be optionally disabled, allowing the demodulator to operate at 250mA. The device can be shut down by an external controller using a single enable pin. When disabled, it typically consumes 20 μA. Samples and production quantities are available.