MAX2831ETM+ Maxim Integrated Products, MAX2831ETM+ Datasheet - Page 22

• Manufacturer Part Number: MAX2831ETM+
• Description: RF Transceiver 2.4GHz to 2.5GHz, 80 2.11g RF Transceiver
• Manufacturer: Maxim Integrated Products

Specifications of MAX2831ETM+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.4GHz to 2.5GHz 802.11g/b
RF Transceivers with Integrated PA
The receiver baseband variable-gain amplifiers provide
62dB of gain control range programmable in 2dB steps.
The VGA gain can be serially programmed through the
SPI interface by setting bits D4:D0 in Register 11 (A3:A0
= 1011) or programmed in parallel through the digital
logic gain-control pins, B5 (pin 14), B4 (pin 34), B3 (pin
8), B2 (pin 11), and B1 (pin 23). Set bit D12 = 1 in
Register 8 (A3:A0 = 1000) to enable serial programming
through the serial interface or set bit D12 = 0 to enable
parallel programming through the external logic pins.
See Table 2 for the gain-step value and Table 3 for
baseband VGA gain-control settings.
The receiver integrates lowpass filters that provide an
upper -3dB corner frequency of 8.5MHz (nominal mode)
with 50dB of attenuation at 20MHz, and 45ns of group
delay ripple in the passband (10kHz to 8.5MHz). The
upper -3dB corner frequency is tightly controlled on-chip
and does not require user adjustment. However, provi-
sions are made to allow fine tuning of the upper -3dB cor-
ner frequency. In addition, coarse frequency tuning
allows the -3dB corner frequency to be set to 7.5MHz
(11b mode), 8.5MHz (11g mode), 15MHz (turbo 1 mode),
and 18MHz (turbo 2 mode) by programming bits D1:D0
in Register 8 (A3:A0 = 1000). See Table 4. The coarse
corner frequency can be fine-tuned approximately ±10%
in 5% steps by programming bits D2:D0 in Register 7
(A3:A0 = 0111). See Table 5 for receiver LPF fine -3dB
corner frequency adjustment.
Table 2. Receiver Baseband VGA Gain-
Step Value (Pins B5:B1 or Register D4:D0,
A3:A0 = 1011)
Table 3. Baseband VGA Gain-Control
Settings in Receiver Gain-Control Register
(Pin B5:B1 or Register D4:D0, A3:A0 = 1011)
22
______________________________________________________________________________________
B5:B1 OR D4:D0
PIN/BIT
11111
11110
11101
00000
B1/D0
B2/D1
B3/D2
B4/D3
B5/D4
:
Receiver Baseband Lowpass Filter
Baseband Variable-Gain Amplifier
GAIN STEP (dB)
Max - 2dB
Max - 4dB
GAIN
Max
Min
16
32
2
4
8
:
The receiver implements programmable AC and near-
DC coupling of I/Q baseband signals. Temporary AC-
coupling is used to quickly remove LO leakage and
other DC offsets that could saturate the receiver out-
puts. When DC offsets have settled, near DC-coupling
is enabled to avoid attenuation of the received signal.
AC-coupling is set (-3dB highpass corner frequency of
600kHz) when a logic-high is applied to RXHP (pin 40).
Near DC-coupling is set (-3dB highpass corner fre-
quency of 100Hz nominal) when a logic-low is applied
to RXHP. Bits D13:D12 in Register 7 (A3:A0 = 0111)
allow the near DC-coupling -3B highpass corner fre-
quency to be set to 100Hz (D13:D12 = 00), 4kHz
(D13:D12 = X1), or 30kHz (D13:D12 = 10). See Table 6.
Table 4. Receiver LPF Coarse -3dB
Corner Frequency Settings in Register
(A3:A0 = 1000)
Table 5. Receiver LPF Fine -3dB Corner
Frequency Adjustment in Register
(A3:A0 = 0111)
Table 6. Receiver Highpass Filter -3dB
Corner Frequency Programming
X = Don’t care.
BITS (D1:D0)
RXHP
BITS (D2:D0)
1
0
0
0
00
01
10
11
000
001
010
011
100
A3:A0 = 0111,
D13:D12
XX
X1
00
10
FREQUENCY (MHz)
-3dB CORNER
% ADJUSTMENT RELATIVE TO
7.5
8.5
15
18
Baseband Highpass Filter
and DC Offset Correction
-3dB HIGHPASS CORNER
COARSE SETTING
100 (recommended)
FREQUENCY (Hz)
100
105
110
90
95
600k
30k
4k
Turbo 1
Turbo 2
MODE
11b
11g