High Dynamic Range 1.5 GHz to 3.8 GHz Active Upconverting Mixer
A new high dynamic range active upconverting mixer from Linear Technology replaces the best of todays passive mixers. The LT5579s wide frequency range of 1.5GHz to 3.8GHz covers the 1.9GHz cellular bands as well as the 2.6GHz and 3.5GHz WiMAX frequency bands. At 2.14GHz, the device offers 27.3dBm Output IP3 linearity and 9.9dB Noise Figure to deliver outstanding transmitter dynamic range. Moreover, the mixer has 2.6dB of conversion gain, the highest in its class. The device integrates Local Oscillator (LO) buffers, requiring only –1dBm to drive the LO port, while offering low –35dBm LO-to-RF leakage.
The LT5579s uncompromising performance is well suited for current and next generation wireless transmitters in basestations, including GSM/EDGE, CDMA, CDMA2000, W-CDMA/UMTS and LTE. Additionally, its performance at higher frequencies supports a wide range of wireless broadband access equipment such as WiMAX or WiBro at 2.7GHz and 3.5GHz, cable CMTS and distribution systems, military radios, digital video broadcast systems, 2.4GHz ISM band transmitters, test instrumentations, micro-cells, pico-cells and wireless repeaters.
The LT5579 has integrated RF transformers at both its RF output and LO input to provide differential to single-ended conversion at both ports. This simplifies system design while eliminating or significantly reducing external matching components.
The LT5579s active, double-balanced design provides several compelling cost-saving benefits. Compared to alternative passive mixers with a typical 8dB conversion loss, the LT5579 offers 2.6dB of gain. This 10dB or more gain advantage eliminates the cost of an extra stage of high power, high linearity RF amplifier. Second, unlike many mixers on the market, the LT5579 can be driven with high signal levels at as much as –5dBm without elevating its outstanding output noise floor above –158dBm/Hz. This feature enables users to drive the transmitter harder while preserving its dynamic range performance. Moreover, most passive mixers have poor LO leakage to the RF output, which is challenging to control, requiring multiple stages of RF filters to achieve adequate suppression. The LT5579s double-balanced design results in –35dBm LO leakage at the devices RF output, relaxing and reducing the external filter stages. Overall, the LT5579 offers outstanding performance, compact size and compelling solution cost.
The LT5579 operates from a single 3.3V supply. Typical quiescent supply current is 226mA.The device comes in a 24-lead 5mm × 5mm QFN surface mount package. Pricing starts at $5.50 each in 1,000 pieces quantities. The product is available immediately from stock.
Summary of Features: LT5579
- Frequency Range: 1.5 GHz to 3.8 GHz
- High Linearity: 27.3 dBm OIP3 @2.14 GHz
- Very Low Output Noise Floor: –158 dBm/Hz @ –5 dBm POUT
- High Conversion Gain: 2.6 dB @ 2.14 GHz
- Low LO Leakage (PLO = –1 dBm): –35 dBm
- Single-Ended RF and LO Interface
Broadband High Linearity Active Upconverting Mixer
Editor's Contact Information
- Doug Dickinson