Philips Semiconductors

Product data

SA2411

+20 dBm single chip linear amplifier for WLAN

2003 Feb 07

6

8. OPERATION

The SA2411 linear amplifier is intended for operation in the 2.4 GHz band, specifically for IEEE 802.11 1 and 2 Mbits/s DSSS, and 5.5 and 11

Msymbols/s CCK standards. Throughout this document, the operating RF frequency refers to the ISM band between 2.4 and 2.5 GHz.

Amplifier Output Power

The SA2411 linear amplifier is designed to give at least 19 dBm output power for an 11 Msymbols/s CCK modulated input carrier. At 19 dBm

output power the ACPR specs are met. The fixed gain amplifier amplifies the input signal by 14.5 dB typically.

Power Mode

The biasing can be adjusted to change the gain and therefore the maximum linear output power. For high supply voltages (>3.2 V) the low-gain

mode is advised. For low supply voltages (<3.3 V) the high-gain mode is advised.

Power Mode

Pin 9 =

Typical output power

Typical small

signal Gain

Typical DC current

(no RF signal)

Typical Current

consumption

High

Floating

20.0 dBm

14.5 dB

35 mA

185 mA @ 20 dBm

Low

Grounded

20.0 dBm

13 dB

28 mA

185 mA @ 20 dBm

Power detector

The power detector current output is linear proportional with the RF output voltage. The RF output power is quadratic proportional to the RF

output voltage. Therefore, the detector is quadratic proportional to the output power. The following relation can be expressed:

20 dBm = 100 mW

1.7 V

300 uA

19 dBm = 79 mW

1.4 V

250 uA

17 dBm = 50 mW

1.0 V

175 uA

15 dBm = 32 mW

0.7 V

125 uA

9 dBm = 8 mW

0.3 V

50 uA

The loading of the detector can be different in the application. The highest accuracy is achieved with 5.6 k

Ω. But other values can be used to

adapt to the maximum input sensitivity of other circuits. Other detector loading values result in other k-factors. The maximum detector voltage is

limited to about 2.4 V.

DC feed at input

There is a possibility to add a DC voltage at the input pins (pin 4 and pin 5) by feeding pin 2. This option should be used in case the SA2411 is

lined up with the SA2400A.