19-2493; Rev 2; 11/03
2.4GHz 802.11b Zero-IF Transceivers
General Description
The MAX2820/MAX2821 single-chip zero-IF transceivers
are designed for the 802.11b (11Mbps) applications
operating in the 2.4GHz to 2.5GHz ISM band. The trans-
ceivers are nearly identical, except the MAX2821 pro-
vides a low-power shutdown mode and an analog
voltage reference output feature and the MAX2820 does
not. The transceivers include all the circuitry required to
implement an 802.11b RF-to-baseband transceiver solu-
tion, providing a fully integrated receive path, transmit
path, VCO, frequency synthesis, and baseband/control
interface. Only a PA, RF switch, RF BPF, and a small
number of passive components are needed to form the
complete radio front-end solution.
The ICs eliminate the need for external IF and base-
band filters by utilizing a direct-conversion radio archi-
tecture and monolithic baseband filters for both
receiver and transmitter. They are specifically opti-
mized for 802.11b (11Mbps CCK) applications. The
baseband filtering and RX and TX signal paths support
the CCK modulation scheme for BER = 10
-5
at the
required sensitivity levels.
The devices are suitable for the full range of 802.11b
data rates (1Mbps, 2Mbps, 5.5Mbps, and 11Mbps) and
also the higher-rate 22Mbps PBCC
TM
standard. The
MAX2820/MAX2821 are available in the very small 7mm
×
7mm 48-lead QFN package.
Features
o
2.4GHz to 2.5GHz ISM Band Operation
o
802.11b (11Mbps CCK and 22Mbps PBCC) PHY
Compatible
o
Complete RF-to-Baseband Transceiver
Direct-Conversion Upconverters and
Downconverters
Monolithic Low-Phase-Noise VCO
Integrated Baseband Lowpass Filters
Integrated PLL with 3-Wire Serial Interface
Digital Bias Control for External PA
Transmit Power Control (Range > 25dB)
Receive Baseband AGC (Range > 65dB)
Complete Baseband Interface
Digital TX/RX Mode Control
Analog Receive Level Detection
o
-97dBm RX Sensitivity at 1Mbps
o
-87dBm RX Sensitivity at 11Mbps
o
+2dBm Transmit Power (11Mbps CCK)
o
Single +2.7V to +3.6V Supply
o
Low-Current Shutdown Mode (MAX2821 only)
o
Very Small 48-Pin QFN Package (s)
MAX2820/MAX2821
Applications
802.11b 11Mbps WLAN
802.11b
+
22Mbps PBCC High-Data-Rate WLAN
802.11a + b Dual-Band WLAN
2.4GHz ISM Band Radios
Ordering Information
PART
MAX2820EGM-TD
MAX2820ETM+TD
MAX2821EGM-TD
MAX2821ETM+TD
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
48 QFN
48 QFN Lead Free
48 QFN
48 QFN Lead Free
PBCC is a trademark of Texas Instruments, Inc.
Pin Configuration/Functional Diagram and Typical
Application Circuit appear at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
2.4GHz 802.11b Zero-IF Transceivers
MAX2820/MAX2821
ABSOLUTE MAXIMUM RATINGS
V
CC
Pins to GND ...................................................-0.3V to +4.2V
RF Inputs: RX_RFP, RX_RFN to GND.........-0.3V to (V
CC
+ 0.3V)
RF Outputs: TX_RFP, TX_RFN to GND..................-0.3V to +4.2V
Baseband Inputs: TX_BBIP, TX_BBIN, TX_BBQP,
TX_BBQN to GND ...................................-0.3V to (V
CC
+ 0.3V)
Baseband Outputs: RX_BBIP, RX_BBIN, RX_BBQP,
RX_BBQN to GND ...................................-0.3V to (V
CC
+ 0.3V)
Analog Inputs: RX_AGC, TX_GC, TUNE, ROSCN,
ROSCP to GND .......................................-0.3V to (V
CC
+ 0.3V)
Analog Outputs: PA_BIAS, CP_OUT, VREF
to GND....................................................-0.3V to (V
CC
+ 0.3V)
Digital Inputs: RX_ON, TX_ON, SHDNB, CSB, SCLK,
DIN, RF_GAIN, RX_1K to GND...............-0.3V to (V
CC
+ 0.3V)
Bias Voltages: RBIAS, BYP ..................................+0.9V to +1.5V
Short-Circuit Duration Digital Outputs: DOUT, RX_DET .........10s
RF Input Power: RX_RFN, RX_RFP.................................+10dBm
Continuous Power Dissipation (T
A
= +70°C)
48-Lead QFN (derate 27.0mW/°C above +70°C) .....2162mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
CAUTION!
ESD SENSITIVE DEVICE
DC ELECTRICAL CHARACTERISTICS
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, RF_GAIN = V
IH
, 0V
≤
V
TX_GC
≤
+2.0V, 0V
≤
V
RX_AGC
≤
+2.0V, RBIAS = 12kΩ, no
input signals at RF and baseband inputs, all RF inputs and outputs terminated into 50Ω, receiver baseband outputs are open, trans-
mitter baseband inputs biased at +1.2V, registers set to default power-up settings, T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at V
CC
= +2.7V, T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETERS
Supply Voltage
Shutdown-Mode Supply Current
(MAX2821 Only)
Standby-Mode Supply Current
Receive-Mode Supply Current
Transmit-Mode Supply Current
SHDNB = V
IL
, RX_ON = V
IL
,
TX_ON = V
IL
SHDNB = V
IH
, RX_ON = V
IL
,
TX_ON = V
IL
SHDNB = V
IH
, RX_ON = V
IH
,
TX_ON = V
IL
SHDNB = V
IH
, RX_ON = V
IL
,
TX_ON = V
IH
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
V
CC
- 0.5
0.5
-5
-5
V
CC
- 0.5
0.5
50
1.25
15
T
A
= -40°C to +85°C, I
LOAD
= ±2mA
1.1
1.2
25
1.3
+5
+5
70
80
CONDITIONS
MIN
2.7
2
25
TYP
MAX
3.6
50
35
40
100
110
85
90
UNITS
V
µA
mA
mA
mA
LOGIC INPUTS: SHDNB, RX_ON, TX_ON, SCLK, DIN, CSB, RF_GAIN
Digital Input Voltage High (V
IH
)
Digital Input Voltage Low (V
IL
)
Digital Input Current High (I
IH
)
Digital Input Current Low (I
IL
)
LOGIC OUTPUTS: DOUT, RX_DET
Digital Output Voltage High (V
OH
) Sourcing 100µA
Digital Output Voltage Low (V
OL
)
RX BASEBAND I/O
RX_AGC Input Resistance
RX I/Q Common-Mode Voltage
RX I/Q Output DC Offsets
VOLTAGE REFERENCE
Reference Voltage Output
Output Impedance
V
Ω
0V
≤
V
RX_AGC
≤
+2.0V
kΩ
V
mV
Sinking 100µA
V
V
µA
µA
V
V
2
_______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceivers
DC ELECTRICAL CHARACTERISTICS (continued)
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, RF_GAIN = V
IH
, 0V
≤
V
TX_GC
≤
+2.0V, 0V
≤
V
RX_AGC
≤
+2.0V, RBIAS = 12kΩ, no
input signals at RF and baseband inputs, all RF inputs and outputs terminated into 50Ω, receiver baseband outputs are open, trans-
mitter baseband inputs biased at +1.2V, registers set to default power-up settings, T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at V
CC
= +2.7V, T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETERS
TX BASEBAND I/O
TX BB Input Common-Mode
Range
TX BBI and BBQ Input Bias
Current
TX BB Input Impedance
TX_GC Input Bias Current
TX_GC Input Impedance
Reference Oscillator Input
Impedance
Differential resistance
0V
≤
V
TX_GC
≤
+2.0V
Resistance
1.0
1.2
-10
100
10
250
1.4
V
µA
kΩ
µA
kΩ
CONDITIONS
MIN
TYP
MAX
UNITS
MAX2820/MAX2821
REFERENCE OSCILLATOR INPUT
20
kΩ
AC ELECTRICAL CHARACTERISTICS—RECEIVE MODE
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, f
RF
and f
LO
= 2400MHz to 2499MHz, f
OSC
= 22MHz or 44MHz, receive baseband
outputs = 500mV
P-P
, SHDNB = RX_ON = V
IH
, TX_ON = V
IL
, CSB = V
IH
, SCLK = DIN = V
IL
, RF_GAIN = V
IH
, 0V
≤
V
RX_AGC
≤
+2.0V,
RBIAS = 12kΩ, I
CP
= +2mA, BW
PLL
= 45kHz, differential RF input matched to 50Ω, registers set to default power-up settings, T
A
=
+25°C, unless otherwise noted. Typical values are at V
CC
= +2.7V, f
LO
= 2437MHz, f
OSC
= 22MHz, unless otherwise noted.) (Note 1)
PARAMETER
RF Frequency Range
LO Frequency Range
RF_GAIN = V
IH
,
V
RX_AGC
= 0V
RF_GAIN = V
IH
,
V
RX_AGC
= +2.0V
RF_GAIN = V
IL
,
V
RX_AGC
= 0V
RF_GAIN = V
IL
,
V
RX_AGC
= +2.0V
RF Gain Step
DSB Noise Figure (Notes 3, 11)
Adjacent Channel Rejection
Input Third-Order Intercept Point (Note 5)
Input Second-Order Intercept Point (Note 6)
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= +25°C
T
A
= +25°C
CONDITIONS
MIN
2400
2400
97
95
33
dB
75
2
30
3.5
4.5
34
49
-14
18
22
60
dB
dBm
dBm
4.5
dB
dB
105
TYP
MAX
2499
2499
UNITS
MHz
MHz
RECEIVER CASCADE PERFORMANCE (RF INPUT TO BASEBAND OUTPUT)
Voltage Gain (Note 2)
From RF_GAIN = V
IH
to RF_GAIN =V
IL
RF_GAIN = V
IH
, RX gain
≥
80dB
RF_GAIN = V
IH
, RX gain = 50dB
RF_GAIN = V
IL
, RX gain = 50dB
RX gain = 70dB (Note 4)
RF_GAIN = V
IH
, RX gain = 80dB
RF_GAIN = V
IL
, RX gain = 50dB
RF_GAIN = V
IH
, RX gain = 80dB
RF_GAIN = V
IL
, RX gain = 50dB
_______________________________________________________________________________________
3
2.4GHz 802.11b Zero-IF Transceivers
MAX2820/MAX2821
AC ELECTRICAL CHARACTERISTICS—RECEIVE MODE (continued)
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, f
RF
and f
LO
= 2400MHz to 2499MHz, f
OSC
= 22MHz or 44MHz, receive baseband
outputs = 500mV
P-P
, SHDNB = RX_ON = V
IH
, TX_ON = V
IL
, CSB = V
IH
, SCLK = DIN = V
IL
, RF_GAIN = V
IH
, 0V
≤
V
RX_AGC
≤
+2.0V,
RBIAS = 12kΩ, I
CP
= +2mA, BW
PLL
= 45kHz, differential RF input matched to 50Ω, registers set to default power-up settings, T
A
=
+25°C, unless otherwise noted. Typical values are at V
CC
= +2.7V, f
LO
= 2437MHz, f
OSC
= 22MHz, unless otherwise noted.) (Note 1)
PARAMETER
LO Leakage
Input Return Loss
BASEBAND FILTER RESPONSE
-3dB Frequency
Default bandwidth setting BW (2:0) = (010)
At 12.5MHz
Attenuation Relative to Passband
At 16MHz
At 20MHz
At 25MHz
BASEBAND OUTPUT CHARACTERISTICS
RX I/Q Gain Imbalance
RX I/Q Phase Quadrature Imbalance
RX I/Q Output 1dB Compression
RX I/Q Output THD
BASEBAND AGC AMPLIFIER
AGC Range
AGC Slope
AGC Response Time
BASEBAND RX PEAK LEVEL DETECTION
RF_GAIN = V
IH
,
RX_DET = V
OL
to V
OH
RF_GAIN = V
IL
,
RX_DET = V
OH
to V
OL
RX Detector Hysteresis
RX Detector Rise Time
With 3dB overdrive
-49
dBm
-54
5
1
dB
µs
V
RX_AGC
= 0 to +2.0V
Peak gain slope
20dB gain step, 80dB to 60dB,
settling to
±1dB
70
60
2
dB
dB/V
µs
Differential voltage into 5kΩ
V
OUT
= 500mV
P-P
at 5.5MHz, Z
L
= 5kΩ||5pF
-1
-5
1
-35
+1
+5
dB
Degrees
V
P-P
dBc
7
40
65
70
85
dB
MHz
With external match
RECEIVER BASEBAND
CONDITIONS
MIN
TYP
-65
15
MAX
UNITS
dBm
dB
RX Detector Trip Point (at RX_RF)
CW signal
AC ELECTRICAL CHARACTERISTICS—TRANSMIT MODE
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, f
RF
and f
LO
= 2400MHz to 2499MHz, f
OSC
= 22MHz or 44MHz, transmit baseband
inputs = 400mV
P-P
, SHDNB = TX_ON = V
IH
, RX_ON = V
IL
, CSB = V
IH
, 0V
≤
V
TX_GC
≤
+2.0V, RBIAS = 12kΩ, I
CP
= +2mA, BW
PLL
=
45kHz, differential RF output matched to 50Ω through a balun, baseband input biased at +1.2V, registers set to default power-up set-
tings, T
A
= +25°C, unless otherwise noted. Typical values are at V
CC
= +2.7V, f
LO
= 2437MHz, f
OSC
= 22MHz, unless otherwise noted.)
PARAMETER
RF Output Frequency Range
LO Output Frequency Range
CONDITIONS
MIN
2400
2400
TYP
MAX
2499
2499
UNITS
MHz
MHz
TRANSMIT SIGNAL PATH: BASEBAND INPUT TO RF OUTPUT
4
_______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceivers
AC ELECTRICAL CHARACTERISTICS—TRANSMIT MODE (continued)
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, f
RF
and f
LO
= 2400MHz to 2499MHz, f
OSC
= 22MHz or 44MHz, transmit baseband
inputs = 400mV
P-P
, SHDNB = TX_ON = V
IH
, RX_ON = V
IL
, CSB = V
IH
, 0V
≤
V
TX_GC
≤
+2.0V, RBIAS = 12kΩ, I
CP
= +2mA, BW
PLL
=
45kHz, differential RF output matched to 50Ω through a balun, baseband input biased at +1.2V, registers set to default power-up set-
tings, T
A
= +25°C, unless otherwise noted. Typical values are at V
CC
= +2.7V, f
LO
= 2437MHz, f
OSC
= 22MHz, unless otherwise noted.)
PARAMETER
CONDITIONS
V
IN
= 400mV
P-P
at
5.5MHz,
V
TX_GC
= 0V,
I/Q CW signal (Note 7)
T
A
= +25°C
T
A
= -40°C to
+85°C
MIN
-1
-2
-37
dBc
-59
-40
-30
-80
-40
-55
-60
-43
-45
-135
15
10
At 22MHz
At 44MHz
0V
≤
V
TX_GC
≤
+2.0V
Peak gain slope
V
TX_GC
= +2.0V to 0V step
25
50
30
40
0.3
dBm/Hz
dB
MHz
dB
dBm
dBm
dBc
TYP
+3
dBm
MAX
UNITS
MAX2820/MAX2821
TX RF Output Power
TX RF ACPR (Note 8)
-22MHz
≤
f
OFFSET
≤
-11MHz,
11MHz
≤
f
OFFSET
≤
22MHz
-33MHz
≤
f
OFFSET
< -22MHz,
22MHz < f
OFFSET
≤
33MHz
Unwanted sideband
f
RF
= 2400MHz to
2483MHz
2
×
f
LO
3
×
f
LO
f
RF
< 2400MHz
f
RF
= 2500MHz to 3350MHz
f
RF
> 3350MHz
f
OFFSET
≥
22MHz, 0V
≤
V
TX_GC
≤
+2.0V
With external match
LO signal
Spurs >
±22MHz
In-Band Spurious Signals Relative to
Modulated Carrier
TX RF Harmonics
TX RF Spurious Signal Emissions
(Outside 2400MHz to 2483.5MHz)
Nonharmonic Signals
TX RF Output Noise
TX RF Output Return Loss
TX BASEBAND FILTER RESPONSE
-3dB Frequency
Attenuation Relative to Passband
TX GAIN-CONTROL CHARACTERISTICS
Gain-Control Range
Gain-Control Slope
Gain-Control Response Time
dB
dB/V
µs
AC ELECTRICAL CHARACTERISTICS—PA BIAS
(MAX2820/MAX2821 EV kit: V
CC
= +2.7V to +3.6V, SHDNB = V
IH
, TX_ON = V
IH
, CSB = V
IH
, PA_BIAS enabled, RBIAS = 12kΩ, regis-
ters set to default power-up settings, T
A
= +25°C, unless otherwise noted. Typical values are at V
CC
= +2.7V, unless otherwise noted.)
PARAMETER
Resolution
Full-Scale Output Current
LSB Size
Output Voltage Compliance Range
Settling Time
(Note 11)
Relative to rising edge of CSB, zero to full-
scale step 0000
→
1111, settle to 1/2 LSB,
2pF load
1.0
CONDITIONS
MIN
TYP
4
300
20
1.2
1
1.3
MAX
UNITS
Bits
µA
µA
V
µs
_______________________________________________________________________________________
5
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