Philips Semiconductors

Product specification

SA2421

2.45 GHz low voltage RF transceiver

2000 Mar 13

6

Table 1.

Truth Table

Chip-En

ATT-SW

Mode

LNA Gain

Predriver

0

X

X

Sleep

N/S

off

off

1

1

0

Receive

+14.3 dB

on

off

1

0

0

Receive

–19 dB

on

off

1

X

1

Transmit

N/S

off

on

FUNCTIONAL DESCRIPTION

The SA2421 is a 2.45 GHz transceiver front-end available in the

TSSOP-24 package. This integrated circuit (IC) consists of a low

noise amplifier (LNA) and up- and down-converters. There is an

enable/disable switch available to power up/down the entire chip in

1

µs, typically. This transceiver has several unique features.

The LNA has two operating modes: 1) high gain mode with a gain =

+14.3 dB; and 2) low gain mode with a gain –19 dB. The switch for

this option is internal and is controlled externally by high and low

logic to the pin. When the LNA is switched into the attenuation

mode, active matching circuitry (on-chip) is switched in (reducing the

number of off-chip components required). To reduce power

consumption when the chip is transmitting, the LNA is automatically

switched into a “sleep” mode (internally) without the use of external

circuitry.