Datasheet
2.4GHz to 2.5GHz 802.11g/b RF Transceiver, PA,
and Rx/Tx/Antenna Diversity Switch
Transmitter
The transmitter integrates baseband lowpass filters,
direct-upconversion mixers, a VGA, a PA driver, and a lin-
ear RF PA with a power detector. A logic-high on the
RXTX input (pin 48) and a logic-high on the SHDN input
(pin 12) enable the transmitter. The PA outputs are routed
to ANT2, regardless of the state at ANTSEL.
Transmitter I/Q Baseband Inputs
The differential analog inputs of the transmitter baseband
amplifier I/Q inputs (TXBBI+, TXBBI-, TXBBQ+, TXBBQ-)
have a differential impedance of 20kΩ || 1pF. The inputs
require an input common-mode voltage of 0.9V to 1.3V,
which is provided by the DC-coupled I and Q DAC out-
puts of the accompanying baseband IC.
Transmitter Baseband Lowpass Filtering
The transmitter integrates lowpass filters that can be
tuned to -3dB corner frequencies of 8MHz (11b),
11MHz (11g), 16.5MHz (turbo 1 mode), and 22.5MHz
(turbo 2 mode) through programming bits D1:D0 in
Register 8 (A3:A0 = 1000) and bit D5:D3 in Register 7
(A3:A0 = 0111). The -3dB corner frequency is tightly
controlled on-chip and does not require user adjust-
ment. Additionally, provisions are made to fine tune the
-3dB corner frequency through bits D5:D3 in the Filter
Programming register (A3:A0 = 0111). See Tables 9
and 10.
Transmitter Variable-Gain Amplifier
The variable-gain amplifier of the transmitter provides
31dB of gain control range programmable in 0.5dB
steps over the top 8dB of the gain control range and in
1dB steps below that. The transmitter gain can be pro-
grammed serially through the SPI interface by setting
bits D5:D0 in Register 12 (A3:A0 = 1100) or in parallel
through the digital logic gain-control pins B6:B1 (pins
3, 6, 8, 11, 14, 23, and 34, respectively). Set bit D10 =
0 in Register 9 (A3:A0 = 1001) to enable parallel pro-
gramming, and set bit D10 = 1 to enable programming
through the 3-wire serial interface. See Table 11 for the
transmitter VGA gain-control settings.
Table 11. Transmitter VGA Gain-Control
Settings
NO.
D5:D0 OR
B6:B1
OUTPUT SIGNAL POWER
63 111111 Max
62 111110 Max - 0.5dB
61 111101 Max - 1.0dB
:: :
49 110001 Max - 7dB
48 110000 Max - 7.5dB
47 101111 Max - 8dB
46 101110 Max - 8dB
45 101101 Max - 9dB
44 101100 Max - 9dB
:: :
5 000101 Max - 29dB
4 000100 Max - 29dB
3 000011 Max - 30dB
2 000010 Max - 30dB
1 000001 Max - 31dB
0 000000 Max - 31dB
Table 9. Transmitter LPF Coarse -3dB
Corner Frequency Settings in Register
(A3:A0 = 1000)
BITS (D1:D0)
-3dB CORNER
FREQUENCY (MHz)
MODE
00 8 11b
01 11 11g
10 16.5 Turbo 1
11 22.5 Turbo 2
Table 10. Transmitter LPF Fine -3dB
Corner Frequency Adjustment in
Register (A3:A0 = 0111)
BITS (D5:D3)
% ADJUSTMENT RELATIVE TO
COARSE SETTING
000 90
001 95
010 100
011 105
100 110 (11g)
101 115
101–111 Not used
Maxim Integrated
23
MAX2830