A 1 W, 900 MHz HBT Power Amplifier

EiC Corp.Fremont, CA

Today’s cellular and portable communications equipment is expected to feature high power and efficiency while operating from a single low voltage supply. The system’s power amplifier must be able to meet these qualifications. The model ES-2067 GaAs heterojunction bipolar transistor (HBT) power amplifier has been specifically optimized to provide high power and efficiency in the 900 MHz cellular, and industrial, scientific and medical (ISM) frequency bands, as well as other 800 to 1000 MHz applications while operating from a +3.6 to +6.0 V DC supply. The device also is easily matched to obtain optimum power and efficiency and is equipped with a power-down mode that provides additional input power savings. The unit is housed in a low cost, surface-mountable plastic SOIC-8 package that contains a metallic ground slug for maximum heat transfer.

The ES-2067 power amplifier achieves 32 dB of small-signal gain and provides +30 dBm power output at the 1 dB gain compression point (P1dB) operating from a 3.6 V DC supply at 25°C, as shown in Figure 1 . Figure 2 shows the amplifier’s gain characteristics vs. frequency. The device features high linearity and is capable of multiple-class operation by utilizing the power-down input pin as an analog control port. Class AB operation results when the VPD voltage is set to 3.6 V DC. Setting the VPD to below 2.7 V DC turns the ES-2067 amplifier off, resulting in a quiescent current drain of less than 10 m A (typically 1 m A).

With 30 dB of gain, the device is easily optimized for 902 to 925 MHz operation and the output power can be lowered by adjusting VPD . (The amplifier’s gain is affected slightly by changes in VPD .) In addition, the power amplifier maintains good stability into an output load SWR of 10 rotated through all phases.

Table I
Typical Performance Specifications

Frequency (MHz)

500 to 1000

Gain (dB) (typ)

32

Saturated output power (dBm)

31

Output (dBm)
at 1dB compression
at third order intercept


29.5
40

Input return loss (dB)

10

Power-added efficiency (%)
at P1dB
at P6dB


35
48

Supply Current (mA)

660

Supply Voltage (V DC)

3.6 to 6.0

Power-down current ( m A) (max)

10

Table 1 lists typical key performance specifications of the device while operating at 3.6 V DC and 25°C at a frequency of 900 MHz. Figure 3 shows the unit’s output power and adjacent-channel power (ACP) vs. input power performance for an IS-54 signal at 900 MHz and 3.6 V at 25°C.

Applications for the ES-2067 power amplifier include use as a final amplifier in cellular- and ISM-band equipment. The +3.6 to 6.0 V DC supply requirement permits the amplifier to be used in most hand-held battery equipment applications. The device also is suitable for use in two-way paging, wireless data and wireless local area network applications. Fully assembled evaluation boards are available.

EiC Corp.,
Fremont, CA
(510) 445-4700.