A 165 W LDMOS FET for 900 MHz Operation

An internally matched, common source, N-channel, enhancement-mode laterally diffused metal-oxide semiconductor (LDMOS) FET intended for large-signal amplifier applications in the 860 to 900 MHz frequency range has been developed. The model PTF 10100 LDMOS FET is rated at 165 W minimum power output and is optimized for amplification of cellular base station signals.

The new device is designed in a push-pull configuration and features a typical drain efficiency of 50 percent, resulting in lower power consumption. It supports the new digital modulations as well as traditional analog applications. The PTF 10100 FET operates from a standard 28 V DC supply with a power gain of 13 dB (typ), and its rugged design permits operation into a 10:1 output load mismatch without device degradation. In addition, the new device has a drain-source breakdown voltage of 65 V (min) and external circuitry is minimized due to its internally matched feature, increasing reliability and improving manufacturability for high volume production. Figure 1 shows the PTF 10100 FET's typical output power and efficiency vs. input power at 880 MHz with VDD = 28 V and IDQ = 1.8 A total. Figure 2 shows typical gain, output power at 1 dB compression and efficiency vs. frequency.

One of the more significant features of the PTF 10100 device is its superior linearity performance. In class AB operation, the third-order intermodulation distortion is an impressive -50 dBc at 50 W peak envelope power (PEP) and just -30 dBc at 150 W PEP. Figure 3 shows the device's intermodulation distortion vs. output power for two adjacent input signals at 880 and 880.1 MHz under the bias conditions described previously.

As with other GOLDMOS™ FETs from this family, this device employs ion implantation, nitride surface passivation and full gold metallization to ensure maximum device lifetime and reliability. In addition, 100 percent lot traceability is standard, providing compliance with quality assurance programs.

Ericsson RF Power Products,
Morgan Hill, CA
(408) 776-0633.