Linear launches 6GHz low power direct conversion I / Q modulator ltc5589

Release date：2016-06-30   Views：2037

Linear Technology Corporation has launched a new low-power I / Q modulator ltc5589, which can realize high-performance broadband transmitter operating in the range of 700MHz to 6GHz and powered by battery. The ltc5589 modulator is powered by a single 2.7V to 3.6V power supply and draws only 29.5ma current, which is 50% lower than other solutions. Without calibration, the new modulator exhibits the best sideband rejection performance of - 50dbc and typical carrier leakage of - 43dbm. By using the built-in fine tuning function through SPI bus, the sideband and carrier suppression can be further improved to better than - 60dbc and - 60dbm respectively. In addition, the device has a very low-158.8dbm/hz output noise layer, combined with 19dbm OIP3, so it can achieve excellent transmitter performance.

Ltc5589 supports both narrowband and wideband transmitters. The baseband bandwidth is extended to 92MHz, and the gain flatness is ± 1dB, thus providing 184mhz RF bandwidth at 1.8GHz. The device has low power consumption and reliable performance, which is suitable for a variety of demanding radio and wireless communication applications. These include broadband modems, femtocells and picocells broadband wireless access, wireless amplifiers and portable audio systems, broadband portable field radios, unlicensed band radios, train communications, software defined radios, and portable RF Test equipment, low power microwave return and repeater, telemetry radio and satellite modem.

Previous zero if modulators have excessive carrier leakage and poor sideband rejection, resulting in poor error vector amplitude (EVM) and adjacent channel power ratio (ACPR). Calibration is challenging and relies on digital tuning algorithms in baseband FPGAs using external DAC. Tuning resolution is usually limited. The ltc5589 provides on-chip tuning capabilities for I-channel and Q-channel phase and amplitude mismatches that affect sideband suppression. In addition, the device also has DC offset balance adjustment function, which affects carrier leakage. With the built-in serial port controlled calibration capability, ltc5589 simplifies calibration and can be implemented in a cost-effective manner.

The gain of ltc5589 can be set through the on-chip serial port. A coarse gain control provides 1dB step and 0.1dB adjustable fine gain control. The total gain range is – 19dB to 0dB. Changing the modulator gain will affect the device power supply current (from 9ma to 39mA), so the device can be set to operate at lower power consumption by slightly reducing the gain and performance according to the needs of specific applications. Once set, the gain can be compensated automatically by activating the built-in temperature calibration function.

The ltc5589 is packaged in 4mm x 4mm plastic QFN, providing a small solution for board area. The specified operating temperature range is – 40 ° C to 105 ° C (enclosure). The device has an enable pin for TDD or burst mode transmitter operation. When it is stopped, ltc5589 can save power by absorbing 0.6 μ a (typical value) standby current. The device can be switched on with complete quadrature accuracy in 350 ns. The batch purchase price of ltc5589 for 1000 pieces is $4.45 per piece, and bulk supply has been started. For more information, please visit www.linear.com.cn/product/LTC5589 。

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Low power 6GHz direct conversion I / Q modulator

Performance summary: ltc5589

·Operating frequency 700MHz to 6GHz

·Power consumption 3.3v/29.5ma

·The sideband rejection is - 50dbc at 1.8GHz

·Carrier leakage is - 43dbm at 1.8GHz

·Output IP3 + 19dbm

·Output IP2 + 60.4dbm

·Output noise layer - 158.8dbc/hz

·SPI serial bus control:

O adjustable gain: - 19dB to 0dB (1dB step)

O gain changes affect the power supply current from 9ma to 39mA

O I / Q gain / phase adjustment: sideband suppression up to - 60dbc

O I / Q offset adjustment: carrier leakage up to – 60dbm

The quotation given in this paper is for budgetary purposes only. Local quotations may vary according to local customs duties, taxes, fees and exchange rates.

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