Maxim introduces two mini Lnas to improve GPS reception sensitivity

Maxim has introduced two small, battery-powered LNA (Low Noise Amplifier) models, the MAX2657 and MAX2658, designed for use in the 1575MHz band with GPS capabilities. The two devices combine Maxim's innovative SiGe BiCMOS process and WLP (chip level package) technology with a noise factor of only 0.8dB, greatly improving GPS reception sensitivity. This sensitivity is superior to discrete GaAs and Phempt Lnas as well as highly integrated RF CMOS schemes. Both devices consume less power than competing solutions, and the MAX2658 has higher linearity and better in-band and out-of-band rejection than competing solutions. Ideal applications for these two Lnas include cellular phones, smartphones, PNDS (personal navigation devices) and other GPS-enabled devices (e.g., bicycle chronographs, watches, etc.), and GPS receiver modules.

Excellent reception performance and the importance of ultra-small size

GPS system signals come from satellites in low-Earth orbit, which are usually weak and difficult to receive in cities or regions where there are a lot of interference signals in adjacent frequency bands. In addition, current low-cost single-chip GPS receivers typically use CMOS technology, which does not provide optimal reception sensitivity for front-end Lnas.

Such RF CMOS receivers need to amplify the GPS signal as much as possible (without increasing noise) with the help of an external LNA to properly receive the satellite signal and determine the actual position. The use of additional Lnas increases the cost and size of the device, just as device manufacturers want to keep them as low as possible without compromising performance. As a result, manufacturers are wary of small sizes (" How small can you be? "). It is not surprising that there is an urgent need for low-cost, high-performance Lnas, which will be the key to differentiating high-performance GPS from ordinary GPS.

Advantages of low power and high linearity

The MAX2657's operating power supply current is only 4mA (typical value), which greatly extends the battery life of GPS devices in the hands of consumers. The MAX2658 delivers high linearity performance over competing solutions, with a supply current of only 7.7mA. When not in use, the logic inside the device enables the shutdown mode to reduce the power supply current to less than 1µA.

Some users want their devices to maintain high reception performance in the presence of in-band and out-of-band interference signals. For such needs, the MAX2658 stands out in its class with its high linearity. The MAX2658 is able to effectively receive GPS signals in noisy jamming environments, providing approximately 6dBm in-band and out-of-band IIP3 performance improvements while increasing power current by only 3.5mA.

The benefits of WLP packaging go beyond space savings

The MAX2657 and MAX2658 are in a space-saving WLP package (pin spacing is 0.4mm) and take up only 1mm² of board space. The package size of the WLP is 20% smaller than existing competing solutions, and the two Lnas require only three external components to complete the board design, greatly reducing the board space taken up.

In addition, the miniature package has another important advantage: Due to the ultra-small size of the MAX2657/MAX2658, it can be placed very close to the antenna, providing sufficient signal strength before the signal is amplified and sent to the GPS receiver.

The MAX2657EWT+T and MAX2658EWT+T are powered from 1.6V to 3.3V and operate in the extended temperature range of -40°C to +85°C. The device is available in an ultra-small 6-pin WLP package. MAX2657EVKIT and MAX2658EVKIT are available for board level evaluation.