Raytheon RF Components

362 Lowell Street

Andover, MA 01810

Revised March 30, 2000

Page 5

www.raytheon.com/micro

Characteristic performance data and specifications are subject to change without notice.

PRODUCT INFORMATION

Table 1

Further Important

Application

Information

An optimal output match for dual mode applications is set by connecting capacitors C8 and

C9 to the package pin using approximately 0.233 inches of a 50 ohm transmission line.

These capacitors should be located adjacent to each other and separated by 0.010 inches.

Lower efficiency will result if a single capacitor of equivalent value were substituted. Fine

adjust the capacitors location to obtain a uniform saturated output power response versus

frequency using a single tone RF input. Saturated output power is typically measured at

+7dBm input power and should be 32.3 to 32.5dBm with a 3.5 volt supply. This condition

will yield typically 50dBc ACPR1 and 60dBc ACPR2 at 28.5dBm output power and a 3.5 volt

supply using a CDMA waveform. If a greater than 50 ohm impedance transmission line is

used to conserve space, transition the line to 50 ohms slightly prior to the optimum tuning

point to avoid undesirable effects from the otherwise residual inductance following the

tuning elements. Once the optimum tuning point has been established this remains fixed for

all other amplifiers. For the dc bias injection circuit choose an inductor with a maximum

series resistance rating of less than 0.15 ohms for best efficiency and overall performance

versus supply voltage. The two 1.5uF tantalum bypass capacitors chosen for this circuit are

low ESR type capacitors with a maximum rating of 1.5 ohms. The capacitor ESR is critical

for achieving the best ACPR possible from the amplifier. Other capacitors may be

substituted, although larger values may be necessary to achieve equivalent performance.

These components should be placed at the tie point for VD1 and VD2 and as close to the

amplifier as possible. Finally, connect pins 1-3 using one solid metal pad as opposed to

three individual pads for each pin.

Same as pin 1.

Same as pin 1.

Place component C12

≤ 0.080 inches from the package pin.

Connect pin immediately to the package base solder pad.

Place components R1 and C11

≤ 0.080 inches from the package pin.

Same as pin 5.

The amplifier input is optimally matched to 50 ohms by locating capacitor C2 at a distance

of 0.138 inches from the package pin. If it is not possible to obtain this separation, adjust

the value of inductor L1 to compensate and obtain the desired match.

Same as pin 5.

Place component C3

≤ 0.080 inches from the package pin. The dc resistance of inductor L2

should be

≤ 0.5 ohms to obtain optimum amplifier performance. Also, connect VD1 and

VD2 at the board component surface and route VG1 and VG2 bias lines to other conductor

layers to minimize any additional ohmic losses on the drain supply line.

Connect to a low impedance negative voltage power supply for stage 2 current control.

From pinchoff, adjust VG2 voltage to achieve 155mA of stage 2 current, ID2. This current is

optimum for high power CDMA operation up to 28.5dBm output power. For improved

performance, adjust to lower current for low power CDMA and analog modes of operation.

Since both stage 1 and stage 2 drains contribute to the total amplifier current the first

stage must be pinched off while adjusting VG2 for a specific ID2 current. A pinchoff

condition is achieved by applying -2.0 to -5.0 volts to the gate pins, VG1 and VG2.

Connect to a low impedance negative voltage power supply for stage 1 current control, ID1.

From pinchoff, adjust VG1 voltage to achieve 35mA of stage 1 current.

The solder pad for this package should be 0.210 inches square. Fill the pad with several

plated-thru vias connecting the pad surface to the RF input and output ground planes.

Insufficient grounding of the package base may cause the amplifier to oscillate or result in

poor amplifier performance.

1

RF OUT AND VD2

2

RF OUT AND VD2

3

RF OUT AND VD2

4G2 AC GND

5GND

6G1 AC GND

7GND

8RF IN

9GND

10

VD1

11

VG2

12

VG1

13

PACKAGE BASE

AND GND

Pin#

Function

Application hints

RMPA0913C-58

3.5V AMPS/CDMA Power Amplifier