19-1209; Rev 0; 10/97
KIT
ATION
EVALU
E
L
B
AVAILA
Low-Voltage IF Transceiver
with Limiter and RSSI
The MAX2511 is a complete, highly integrated IF transceiver for applications employing a dual-conversion
architecture. Alternatively, the MAX2511 can be used
as a single-conversion transceiver if the RF operating
frequency ranges from 200MHz to 440MHz.
In a typical application, the receiver downconverts a
high IF/RF (200MHz to 440MHz) to a 10.7MHz low IF
using an image-reject mixer. Functions include an
image-reject downconverter with 34dB of image suppression followed by an IF buffer that can drive an offchip IF filter; an on-chip limiting amplifier offering 90dB
of monotonic received-signal-strength indication (RSSI);
and a robust limiter output driver. The transmit imagereject mixer generates a clean output spectrum to minimize filter requirements. It is followed by a 40dB
variable-gain amplifier that maintains IM3 levels below
-35dBc. Maximum output power is 2dBm. A VCO and
oscillator buffer for driving an external prescaler are
also included.
The MAX2511 operates from a 2.7V to 5.5V supply and
includes flexible power-management control. Supply
current is reduced to 0.1µA in shutdown mode.
For applications using in-phase (I) and quadrature (Q)
baseband architecture for the transmitter, Maxim offers
a corresponding transceiver product: the MAX2510.
The MAX2510 has features similar to those of the
MAX2511, but upconverts I/Q baseband signals using
a quadrature upconverter.
____________________________Features
♦ Single +2.7V to +5.5V Supply
♦ Complete Receive Path:
200MHz to 440MHz (first IF) to
8MHz to 13MHz (second IF)
♦ Limiter with Differential Outputs (adjustable level)
♦ RSSI Function with 90dB Monotonic Dynamic
Range
♦ Complete Transmit Path:
8MHz to 13MHz (second IF) to
200MHz to 440MHz (first IF)
♦ On-Chip Oscillator with Voltage Regulator
and Buffer
♦ Advanced System Power Management
(four modes)
♦ 0.1µA Shutdown Supply Current
______________Ordering Information
PART
MAX2511EEI
TEMP. RANGE
PIN-PACKAGE
-40°C to +85°C
28 QSOP
__________________Pin Configuration
TOP VIEW
________________________Applications
PWT1900 Wireless Handsets and
Base Stations
PACS, PHS, DECT and Other PCS
Wireless Handsets and Base Stations
400MHz ISM Transceivers
IF Transceivers
Wireless Data Links
Typical Operating Circuit appears at end of data sheet.
LIMIN
1
28 VREF
CZ
2
27 MIXOUT
CZ
3
26 GND
RSSI
4
25
RXIN
GC
5
24
TXOUT
TANK
6
23
TXOUT
GND
7
22 RXIN
VCC
8
21 VCC
TANK
9
MAX2511
20 GND
GND 10
19
VCC
VCC 11
18
TXEN
OSCOUT 12
17
RXEN
LIMOUT 13
16
TXIN
LIMOUT 14
15
TXIN
QSOP
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX2511
_______________General Description
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
ABSOLUTE MAXIMUM RATINGS
VCC to GND .............................................................-0.3V to 8.0V
VCC to Any Other VCC ........................................................±0.3V
TXIN, TXIN Input Voltage............................-0.3V to (VCC + 0.3V)
TXIN to TXIN Differential Voltage ....................................±300mV
RXIN, RXIN Input Voltage ........................................-0.3V to 1.6V
TANK, TANK Voltage ...............................................-0.3V to 2.0V
LIMIN Voltage .............................(VREF - 1.3V) to (VREF + 1.3V)
LIMOUT, LIMOUT Voltage ..............(VCC - 1.6V) to (VCC + 0.3V)
RXEN, TXEN, GC Voltage...........................-0.3V to (VCC + 0.3V)
RXEN, TXEN, GC Input Current ............................................1mA
RSSI Voltage...............................................-0.3V to (VCC + 0.3V)
Continuous Power Dissipation (TA = +70°C)
QSOP (derate 11mW/°C above 70°C) ...........................909mW
Operating Temperature Range
MAX2511EEI ......................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10sec) .............................+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.
DC ELECTRICAL CHARACTERISTICS
(VCC = +2.7V to +5.5V, 0.01µF across CZ and CZ; TANK = TANK; MIXOUT tied to VREF through a 165Ω resistor; GC open, RXIN =
RXIN; TXOUT = TXOUT = VCC; TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
Operating Voltage Range
Digital Input Voltage High
RXEN, TXEN
Digital Input Voltage Low
RXEN, TXEN
MIN
TYP
MAX
UNITS
2.7
3.0
5.5
V
2.0
Digital Input Current High
23
Digital Input Current Low
Typical Supply Current
V
-5
VCC = 3.0V
TA = +25°C
Worst-Case Supply Current
VREF Voltage
Rx mode, RXEN = high,
TXEN = low
24
Tx mode, RXEN = low,
TXEN = high, VGC = 0.5V
26
Standby mode, RXEN = high,
TXEN = high
9.5
Shutdown mode, RXEN = low,
TXEN = low
0.1
2
32
µA
µA
mA
µA
38.5
Tx mode, RXEN = low,
TXEN = high, VGC = 0.5V
45
Standby mode, RXEN = high,
TXEN = high
14.5
Shutdown mode, RXEN = low,
TXEN = low
5
(Note 1)
Internally terminated to 1.35V
mA
µA
VCC / 2 - VCC / 2 VCC / 2 +
100mV
100mV
V
2
kΩ
LIMOUT, LIMOUT
Differential Output Impedance
GC Input Resistance
V
-1
Rx mode, RXEN = high,
TXEN = low
VCC = 2.7V to 5.5V,
TA = -40°C to +85°C
0.4
60
80
_______________________________________________________________________________________
125
kΩ
Low-Voltage IF Transceiver
with Limiter and RSSI
(MAX2511 test fixture, VCC = +3.0V, RXEN = TXEN = low, 0.01µF across CZ and CZ, MIXOUT tied to VREF through 165Ω resistor,
TXIN, TXIN tied to VREF through 50Ω resistor, TXOUT and TXOUT loaded with 100Ω differential, GC open, LIMOUT, LIMOUT loaded
with 2kΩ differential, TANK and TANK driven with -2.5dBm from a 100Ω source; OSCOUT AC-terminated with 50Ω, 330pF at RSSI
pin, 0.1µF at VREF pin, Rx inputs and Tx outputs differentially coupled, PRXIN, RXIN = -28dBm (200Ω system), fRXIN, RXIN = 425MHz,
fLO = 435.7MHz, fTXIN, TXIN = 10.7MHz, TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
21.5
23.6
25.5
UNITS
DOWNCONVERTER (RXEN = high)
Downconverter Mixer Voltage Gain
TA = +25°C
TA = -40°C to +85°C (Note 1)
20
Downconverter Mixer Noise Figure
27
dB
14
dB
(Note 2)
-16
dBm
Input Third-Order Intercept
Two tones at 424MHz and 425MHz,
-30dBm per tone
-11
dBm
Image Rejection
fIMAGE = fLO + fIF = 446.4MHz
Downconverter Mixer Input 1dB
Compression Level
25
MIXOUT Maximum Voltage Swing
Power-Up Time
34
dB
2
Vp-p
Standby to RX or TX (Note 3)
5
LIMITING AMPLIFIER AND RSSI (RXEN = high)
VGC = 0.8V (Note 4)
120
µs
160
Limiter Output Level
VGC = open
475
950
Phase Variation
VGC = 2.0V (PLIMIN = +5dBm)
-75dBm to 5dBm from 50Ω
3.6
degrees
Minimum Linear RSSI Range
-75dBm to 5dBm from 50Ω
80
dB
Minimum Monotonic RSSI Range
-80dBm to 10dBm from 50Ω
90
dB
RSSI Slope
-75dBm to 5dBm from 50Ω
10.6
mV/dB
RSSI Maximum Intercept
(Note 5)
-82
-75
TA = +25°C
±1
±2
RSSI Relative Error
625
mVp-p
1100
TA = -40°C to +85°C (Note 1)
±2.5
dBm
dB
RSSI Rise Time
Rise time to within 1dB accuracy; using a 100pF
capacitor from RSSI to GND
Minimum-Scale RSSI Voltage
At LIMIN input of -75dBm
50
90
135
mV
Maximum-Scale RSSI Voltage
At LIMIN input of 5dBm
850
940
1025
mV
OSCILLATOR (TXEN = RXEN = high)
Frequency Range
Phase Noise
Maximum LO Frequency Pulling
(Note 7)
At 10kHz offset
Standby mode to TX or RX mode
200
440
-88
±36
MHz
dBc/Hz
kHz
LO Leakage
At RXIN port
-65
dBm
Oscillator Buffer Output Power
Maximum Power-Up Time
6.4
TA = +25°C (Note 8)
-12
TA = -40°C to +85°C (Notes 1 and 8)
-13
Shutdown to standby mode (Note 9)
-9
220
µs
dBm
µs
_______________________________________________________________________________________
3
MAX2511
AC ELECTRICAL CHARACTERISTICS
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2511 test fixture, VCC = +3.0V, RXEN = TXEN = low, 0.01µF across CZ and CZ, MIXOUT tied to VREF through 165Ω resistor,
TXIN, TXIN tied to VREF through 50Ω resistor, TXOUT and TXOUT loaded with 100Ω differential, GC open, LIMOUT, LIMOUT loaded
with 2kΩ differential, TANK and TANK driven with -2.5dBm from a 100Ω source; OSCOUT AC-terminated with 50Ω, 330pF at RSSI
pin, 0.1µF at VREF pin, Rx inputs and Tx outputs differentially coupled, PRXIN, RXIN = -28dBm (200Ω system), fRXIN, RXIN = 425MHz,
fLO = 435.7MHz, fTXIN, TXIN = 10.7MHz, TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TRANSMITTER (TXEN = high, VTXIN and VTXIN = 100mVp-p differential)
VGC = 0.5V, TA = +25°C
Output Power
TYP
MAX
UNITS
-44
VGC = open, TA = +25°C
-19
VGC = 2.0V, TA = +25°C
-5
VGC = 2.0V, TA = -40°C to +85°C (Note 1)
-6
dBm
-2
Image Rejection
34
25
dBc
LO Rejection
40
30
dBc
Output 1dB Compression Point
VGC = 2.0V
Output IM3 Level
0.5V < VGC < 1.87V
-40dBm < POUT < -10dBm (Note 10)
2
-40
VGC = 2.0V
-35
dBm
dBc
Note 1: Guaranteed by design and characterization.
Note 2: Driving RXIN or RXIN with a power level greater than the 1dB compression level forces the input stage out of its linear
range, causing harmonic and intermodulation distortion. The RSSI output increases monotonically with increasing input
levels beyond the mixer’s 1dB compression level.
Note 3: Assuming the supply voltage has been applied, this includes settling of the limiter offset correction and the Rx or Tx bias
stabilization time. Guaranteed by design.
Note 4: LIMOUT, LIMOUT loaded with 2kΩ differential. With no load, the output swing is approximately twice as large.
Note 5: The RSSI maximum intercept is the maximum input power (over a statistical sample of parts) at which the RSSI output is 0V.
This point is extrapolated from the linear portion of the RSSI voltage versus limiter input power. This specification and the
RSSI slope define the ideal behavior of the RSSI function (the slope and intercept of a straight line), while the RSSI relative
error specification defines the deviations from this line. See the RSSI Output Voltage vs. Limiter Input Power graph in the
Typical Operating Characteristics.
Note 6: The RSSI relative error is the deviation from the best-fitting straight line of RSSI output voltage versus limiter input power.
A 0dB relative error is exactly on this line. The limiter input power range for this test is -75dBm to +5dBm from 50Ω. See the
RSSI Relative Error graph in the Typical Operating Characteristics .
Note 7: Operation outside this frequency range is possible but has not been characterized. At lower frequencies, it might be
necessary to overdrive the oscillator with an external signal source.
Note 8: If a larger output level is required, a higher value of load resistance (up to 100Ω) may be used.
Note 9: This assumes that the supply voltage has been applied, and includes the settling time of VREF, using the Typical
Operating Circuit.
Note 10: Using two tones at 10.7MHz and 10.8MHz, 50mVp-p per tone at TXIN, TXIN. See Typical Operating Characteristics.
4
_______________________________________________________________________________________
Low-Voltage IF Transceiver
with Limiter and RSSI
(MAX2511 test fixture, VCC = +3.0V, 0.01µF across CZ and CZ, MIXOUT tied to VREF through 165Ω resistor, TXIN, TXIN tied to VREF
through 50Ω resistor, TXOUT and TXOUT loaded with 100Ω differential, GC open, LIMOUT, LIMOUT loaded with 2kΩ differential,
TANK and TANK driven with -2.5dBm from a 100Ω source; OSCOUT AC-terminated with 50Ω, 100pF at RSSI pin, 0.1µF at VREF pin,
Rx inputs and Tx outputs differentially coupled, PRXIN, RXIN = -28dBm (200Ω system), fRXIN, RXIN = 425MHz, fLO = 435.7MHz, fTXIN,
TXIN = 10.7MHz, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
Tx MODE
40
45
30
20
Rx MODE
20
15
15
10
10
5
0
0
25
85
Tx MODE
35
30
STANDBY MODE
STANDBY MODE
5
-40
40
25
25
Rx MODE
20
2.7 3.0
3.5
4.0
4.5
5.0
5.5
0
0.4
0.8
1.2
1.6
2.0
2.4
TEMPERATURE (°C)
VCC (V)
GC VOLTAGE (V)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
DOWNCONVERTER MIXER CONVERSION
GAIN vs. SUPPLY VOLTAGE
DOWNCONVERTER GAIN
vs. RXIN FREQUENCY
TA = +85°C
GAIN (dB)
1.5
TA = -40°C
23
1.0
TA = +25°C
22
TA = +85°C
21
RXEN = HIGH
TXEN = LOW
24.5
VOLTAGE GAIN (dB)
2.0
24
25.0
MAX2511-TOC05
25
MAX2511 TOC04
2.5
2.8
3.2
MAX2511/TOC07A
Rx MODE
ICC (mA)
25
ICC (mA)
ICC (mA)
30
ICC (µA)
Tx MODE
35
50
MAX2511 TOC02
35
MAX2511 TOC01
40
SUPPLY CURRENT
vs. GC VOLTAGE
MAX2511 TOC03
SUPPLY CURRENT
vs. TEMPERATURE
24.0
23.5
23.0
TA = +25°C
0.5
22.5
20
RXEN = HIGH
TXEN = LOW
TA = -40°C
0
2.7 3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
22.0
19
2.7 3.0
3.5
4.0
4.5
VCC (V)
5.0
5.5
200
275
350
425
RXIN FREQUENCY (MHz)
_______________________________________________________________________________________
5
MAX2511
__________________________________________Typical Operating Characteristics
____________________________Typical Operating Characteristics (continued)
(MAX2511 test fixture, VCC = +3.0V, 0.01µF across CZ and CZ, MIXOUT tied to VREF through 165Ω resistor, TXIN, TXIN tied to
VREF through 50Ω resistor, TXOUT and TXOUT loaded with 100Ω differential, GC open, LIMOUT, LIMOUT loaded with 2kΩ differential, TANK and TANK driven with -2.5dBm from a 100Ω source; OSCOUT AC-terminated with 50Ω, 100pF at RSSI pin, 0.1µF at
VREF pin, Rx inputs and Tx outputs differentially coupled, PRXIN, RXIN = -28dBm (200Ω system), fRXIN, RXIN = 425MHz, fLO = 435.7MHz,
fTXIN, TXIN = 10.7MHz, TA = +25°C, unless otherwise noted.)
DOWNCONVERTER-MIXER IMAGE
REJECTION vs. TEMPERATURE
AND SUPPLY VOLTAGE
30
38
36
VCC = 5.5V
34
VCC = 2.7V
32
VCC = 3.0V
30
30
25
20
15
10
28
200
250
300
350
0
-40
400 425
-20
0
20
40
60
85
0
10
20
30
40
FREQUENCY (MHz)
TEMPERATURE (°C)
IF FREQUENCY (MHz)
DOWNCONVERTER INPUT 1dB
COMPRESSION LEVEL
RXIN DIFFERENTIAL INPUT IMPEDANCE
vs. FREQUENCY
LIMITER OUTPUT LEVEL
vs. GC VOLTAGE
50
TA = +25°C
40
TA = -40°C
30
20
TXEN = LOW
RXEN = HIGH
10
0
150
100
50
0
RX MODE REAL
-50
RX MODE IMAGINARY
-100
-150
RX OFF IMAGINARY
-250
2.7 3.0
3.5
4.0
4.5
VCC (V)
5.0
5.5
1.2
TA = -40°C
TA = +25°C
1.0
TA = +85°C
.8
.6
.4
.2
-200
200
300
400
FREQUENCY (MHz)
50
MAX2511-TOC11
RX OFF REAL
200
OUTPUT LEVEL (Vp-p)
60
250
MAX2511/TOC10
TA = +85°C
REAL AND IMAGINARY IMPEDANCE (Ω)
MAX2511-TOC09
70
6
5
26
25
TXEN = LOW
RXEN = HIGH
35
IMAGE REJECTION (dB)
35
40
MAX2511 TOC0A2
MAX2511/TOC0A1
40
40
Rx IMAGE REJECTION (dBc)
IMAGE REJECTION (dB)
45
DOWNCONVERTER IMAGE REJECTION
vs. IF FREQUENCY
MAX2511-TOC08
DOWNCONVERTER IMAGE REJECTION
vs. RXIN FREQUENCY
1dB COMPRESSION LEVEL (mVrms)
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
TXEN = LOW
RXEN = HIGH
0
500
0
0.4
0.8
1.2
1.6
2.0
GC VOLTAGE (V)
_______________________________________________________________________________________
2.4
2.8
3.0
Low-Voltage IF Transceiver
with Limiter and RSSI
Tx OFF REAL
-100
-200
-300
-400
Tx OFF
IMAGINARY
-500
-600
Tx MODE
IMAGINARY
-700
-800
-20
MAX2511-TOC16a
Tx MODE REAL
-30
-40
-50
-60
-70
-80
-90
-900
-100
-1000
0.8
1.2
1.6
2.0
2.7
200
MAX2511tocC
-0.5
Tx POUT (dBm)
VCC = 2.7V
VCC = 5.5V
-30
-2.0
-2.5
VCC = 5.5V
-3.0
-3.5
-35
-40
VCC = 5.5V
VCC = 2.7V
VGC = 0.5V
-50
-5.0
0
20
40
TEMPERATURE (°C)
1.6
2.0
2.4
2.8
35
30
25
20
15
10
-4.5
-20
1.2
-4.0
-45
-40
0.8
UPCONVERTER IMAGE REJECTION
vs. IF FREQUENCY
IMAGE REJECTION (dB)
-1.5
-15
VGC = OPEN
VCC = 2.7V
-1.0
0.4
GC VOLTAGE (V)
TRANSMITTER OUTPUT POWER
vs. TEMPERATURE AND SUPPLY
GC VOLTAGE (GC = 2V)
VCC = 2.7V
VCC = 5.5V
0
500
TRANSMITTER OUTPUT POWER
vs. TEMPERATURE, SUPPLY,
AND GC VOLTAGE
-10
-25
400
FREQUENCY (MHz)
VGC = 2V
-20
300
GC VOLTAGE (V)
0
-5
2.4
MAX2511 TOC20
0.4
MAX2511TOCD
0
TX PORT (dBm)
0
INTERMODULATION POWER (dBm)
205MHz
260MHz
350MHz
430MHz
100
MAX2511 TOC21
MAX2511TOCB
5
0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
-65
UPCONVERTER IM3 LEVELS vs.
GC VOLTAGE (POWERS ARE PER TONE)
TRANSMITTER DIFFERENTIAL
OUTPUT IMPEDANCE vs. FREQUENCY
REAL AND IMAGINARY IMPEDANCE Ω
Tx POUT (dBm)
TRANSMITTER OUTPUT POWER
vs. GC VOLTAGE (FREQUENCY)
60
85
5
-40
-20
0
20
40
TEMPERATURE (°C)
60
85
0
10.7
20
30
40
50
IF FREQUENCY (MHz)
_______________________________________________________________________________________
7
MAX2511
____________________________Typical Operating Characteristics (continued)
(MAX2511 test fixture, VCC = +3.0V, 0.01µF across CZ and CZ, MIXOUT tied to VREF through 165Ω resistor, TXIN, TXIN tied to
VREF through 50Ω resistor, TXOUT and TXOUT loaded with 100Ω differential, GC open, LIMOUT, LIMOUT loaded with 2kΩ differential, TANK and TANK driven with -2.5dBm from a 100Ω source; OSCOUT AC-terminated with 50Ω, 100pF at RSSI pin, 0.1µF at
VREF pin, Rx inputs and Tx outputs differentially coupled, PRXIN, RXIN = -28dBm (200Ω system), fRXIN, RXIN = 425MHz, fLO = 435.7MHz,
fTXIN, TXIN = 10.7MHz, TA = +25°C, unless otherwise noted.)
____________________________Typical Operating Characteristics (continued)
(MAX2511 test fixture, VCC = +3.0V, 0.01µF across CZ and CZ, MIXOUT tied to VREF through 165Ω resistor, TXIN, TXIN tied to
VREF through 50Ω resistor, TXOUT and TXOUT loaded with 100Ω differential, GC open, LIMOUT, LIMOUT loaded with 2kΩ differential, TANK and TANK driven with -2.5dBm from a 100Ω source; OSCOUT AC-terminated with 50Ω, 100pF at RSSI pin, 0.1µF at
VREF pin, Rx inputs and Tx outputs differentially coupled, PRXIN, RXIN = -28dBm (200Ω system), fRXIN, RXIN = 425MHz, fLO = 435.7MHz,
fTXIN, TXIN = 10.7MHz, TA = +25°C, unless otherwise noted.)
RSSI RELATIVE ERROR
vs. LIMIN INPUT AND TEMPERATURE
RSSI OUTPUT VOLTAGE vs. LIMIN
INPUT POWER AND TEMPERATURE
1
.9
4
RSSI ERROR (dB)
.5
TA = +85°C
.4
.3
2
1
0
-1
-2
TA = +25°C
TA = +25°C
TA = -40°C
-3
.2
-4
TA = -40°C
.1
-5
0
-120 -100
-80
-60
-40
-20
0
-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20
20
PLIMIN (dBm, 50Ω)
PLIMIN (dBm, 50Ω)
TRANSMITTER IMAGE REJECTION vs.
TEMPERATURE AND SUPPLY VOLTAGE
MIXER INPUT-REFERRED RSSI VOLTAGE
vs. RXIN INPUT POWER
1.1
MAX2511TOCE
40
38
VCC = 5.5V
1.0
0.9
RSSI VOLTAGE (V)
VCC = 3.3V
36
34
32
VCC = 2.7V
MAX2511-TOC15
RSSI OUTPUT (V)
.6
TA = +85°C
3
.8
.7
MAX2511 TOC2514
5
MAX2511 TOC13
1.1
Tx IMAGE REJECTION (dBc)
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
0.8
0.7
0.6
0.5
0.4
30
0.3
28
0.2
26
-40
-20
0
20
40
TEMPERATURE (°C)
8
60
85
0.1
-120 -100
-80
-60
-40
-20
0
10
PRXIN (dBm, 50Ω)
_______________________________________________________________________________________
Low-Voltage IF Transceiver
with Limiter and RSSI
PIN
NAME
FUNCTION
1
LIMIN
Limiter Input. Connect a 330Ω (typ) resistor to VREF for DC bias, as shown in the Typical Operating
Circuit.
2, 3
CZ, CZ
Offset-Correction Capacitor pins. Connect a 0.01µF capacitor between CZ and CZ.
4
RSSI
5
GC
Gain-Control pin in transmit mode. Applying a DC voltage to GC between 0V and 2.0V adjusts the
transmitter gain by 40dB. In receive mode, GC adjusts the limiter output level from 0Vp-p to about
1Vp-p. This pin’s input impedance is typically 80kΩ terminated to 1.35V.
6, 9
TANK, TANK
Tank pins. Connect the resonant tank across these pins, as shown in the Typical Operating Circuit.
7, 10
GND
Ground. Connect GND to the PC board ground plane with minimal inductance.
8, 11
VCC
Supply Voltage. Bypass VCC directly to GND. See the Layout Issues section.
Receive-Signal-Strength-Indicator Output. The voltage on RSSI is proportional to the signal power at
LIMIN. The RSSI output sources current pulses into an external capacitor (100pF typ). The output is
internally terminated with 6kΩ, and this RC time constant sets the decay time.
12
OSCOUT
Oscillator-Buffer Output. OSCOUT provides a buffered oscillator signal (at the oscillator frequency)
for driving an external prescaler. This pin is a current output and must be AC-coupled to a resistive
load. The output power is typically -9dBm into a 50Ω load. If a larger output swing is required, a
larger load resistance (up to 100Ω) can be used.
13, 14
LIMOUT,
LIMOUT
Differential Outputs of the Limiting Amplifier. LIMOUT and LIMOUT are open-collector outputs that
are internally pulled up to VCC through 1kΩ resistors.
15, 16
TXIN, TXIN
Differential Inputs of the Image-Reject Upconverter Mixer. TXIN and TXIN are high impedance and
must be pulled up to VCC through two external resistors whose value is equal to the desired terminating impedance (50Ω to 50kΩ).
17
RXEN
Receiver-Enable pin. When high, RXEN enables the receiver if TXEN is low. If both RXEN and TXEN
are high, the part is in standby mode; if both are low, the part is in shutdown. See the Power
Management section for more details.
18
TXEN
Transmitter-Enable pin. When high, TXEN enables the transmitter, if RXEN is low. If both TXEN and
RXEN are high, the part is in standby mode; if both are low, the part is in shutdown. See the Power
Management section for more details.
19, 21
VCC
Bias VCC Supply pins. Decouple these pins to GND. See the Layout Issues section.
20
GND
Receiver/Transmitter Ground pin. Connect to the PC board ground plane with minimal inductance.
22, 25
RXIN, RXIN
23, 24
TXOUT, TXOUT
Differential Outputs of the Image-Reject Upconverter. TXOUT and TXOUT must be pulled up to VCC
with two external inductors and AC coupled to the load.
26
GND
Receiver Front-End Ground. Connect GND to the PC board ground plane with minimal inductance.
27
MIXOUT
Single-Ended Output of the Image-Reject Downconverter. MIXOUT is high impedance and must be
biased to the VREF pin through an external terminating resistor whose value depends on the interstage filter characteristics. See the Applications Information section for more details.
28
VREF
Reference Voltage pin. VREF is used to provide an external bias voltage for the MIXOUT and LIMIN
pins. Bypass this pin with a 0.1µF capacitor to ground. VREF voltage is equal to VCC / 2. See the
Typical Operating Circuit for more information.
Differential Inputs of the Image-Reject Downconverter Mixer. In most applications, an impedance
matching network is required. See the Applications Information section for more details.
_______________________________________________________________________________________
9
MAX2511
______________________________________________________________Pin Description
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
IF BPF
LIMIN
VREF
MIXOUT
CZ
CZ
OFFSET
CORRECTION
RECEIVE IMAGE-REJECT MIXER
90°
RXIN
Σ
RXIN
LIMITER
GM
LIMOUT
0°
LIMOUT
VGA
TANK
RSSI
0°
90°
TANK
RSSI
VREF = VCC / 2
LO PHASE
SHIFTER
OSCOUT
RXEN
BIAS
TXEN
TXIN
PA
TXOUT
0°
VGA
Σ
TXIN
TXOUT
90°
TRANSMIT IMAGE-REJECT MIXER AND VGA/PA
MAX2511
VOLTAGE GAIN
AND BIAS CONTROL
GC
Figure 1. Functional Diagram
_______________Detailed Description
The following sections describe each of the blocks
shown in Figure 1.
Receiver
The receiver consists of two basic blocks: the imagereject downconverter mixer and the limiter/RSSI section.
The receiver inputs are the RXIN, RXIN pins, which
should be AC coupled and may require a matching network, as shown in the Typical Operating Circuit. To
design a matching network for a particular application,
refer to the Applications Information section and the
receiver input impedance plots in the Typical Operating
Characteristics.
10
Image-Reject Mixer
The downconverter is implemented using an imagereject mixer consisting of an input buffer with dual outputs, each of which is fed to a double-balanced mixer.
The LO signal is generated by an on-chip oscillator and
an external tank circuit. The buffered oscillator signal
drives a quadrature phase generator that provides two
outputs with 90° of phase shift between them. This pair
of LO signals is fed to the two receive mixers. The
mixer’s outputs are then passed through a pair of
phase shifters, which provide 90° of phase shift across
their outputs. The resulting two signals are then
summed together. The final phase relationship is such
that the desired signal is reinforced, and the image signal is largely canceled. The downconverter mixer’s
______________________________________________________________________________________
Low-Voltage IF Transceiver
with Limiter and RSSI
Limiter
The signal passes through an external IF bandpass filter into the limiter input (LIMIN). LIMIN is a singleended input that is centered around the VREF pin
voltage. Open-circuit input impedance is typically
greater than 10kΩ terminated to VREF. For proper operation, LIMIN must be tied to VREF through the filter terminating impedance (not more than 1kΩ). The limiter
provides a constant output level, which is largely independent of the limiter input-signal level over an 80dB
input range.
The adjustable output level allows easy interfacing of
the limiter output to the downstream circuitry. The limiter’s output drives a variable-gain amplifier that adjusts
the limited output level from 0Vp-p to typically 1Vp-p as
the GC pin voltage is adjusted from 0.5V to 2.0V. Using
this feature allows the downstream circuitry, such as an
analog-to-digital converter (ADC), to run at optimum
performance by steering the limiter’s output level to
match the desired ADC input level. GC is also used for
transmit (Tx) gain adjustment in Tx mode, so be sure to
keep the voltage at an appropriate value for each mode.
to less than -40dBm by controlling the GC pin. For
output levels between -10dBm and -40dBm, -40dBc
IM3 levels are maintained. The resulting signal appears
as a differential output on TXOUT and TXOUT, which
expect a 100Ω differential load impedance.
TXOUT and TXOUT are open-collector outputs and
need external pull-up inductors to VCC for proper operation. They also need a DC block so the load does not
affect DC biasing. A shunt resistor across TXOUT,
TXOUT can be used to back-terminate an external filter,
as shown in the Typical Operating Circuit. It is possible
to use the receiver inputs RXIN and RXIN to provide
this termination, as described in the Filter Sharing section. For single-ended operation, tie the unused input to
VCC.
Local Oscillator and Oscillator Buffer
The on-chip LO requires only an external LC tank circuit
for operation. The tank circuit is connected across
TANK and TANK. A dual varactor diode is typically used
to adjust the frequency in a phase-locked loop (PLL).
See the Applications Information section for the tank circuit design equations. Keep the resonator’s Q as high
VCC
Received-Signal-Strength Indicator
The RSSI output provides a linear indication of the
received power level on the LIMIN input. The RSSI
monotonic dynamic range exceeds 90dB while providing better than 80dB linear range. The RSSI output
pulses current into an external filter capacitor (typically
100pF). The output is internally terminated with 6kΩ to
GND, and this R-C time constant sets the decay time.
Transmitter
The image-reject upconverter mixer operates in a fashion similar to the downconverter mixer. The transmit
mixer consists of an input buffer amplifier that drives
on-chip IF phase shifters. The shifted signals are then
input to a pair of double-balanced mixers, which are
driven with the same quadrature (Q) LO source used
by the receiver. The mixer outputs are summed together, largely canceling the image signal component. The
image-canceled signal from the mixer outputs is fed
through a variable-gain amplifier (VGA) with 40dB of
gain-adjust range.
The VGA output is connected to a driver amplifier with
an output 1dB compression point of 2dBm. The output
power can be adjusted from approximately 2dBm
VBIAS
Figure 2. Simplified Oscillator Equivalent Circuit
______________________________________________________________________________________
11
MAX2511
output is buffered and converted to a single-ended current output at the MIXOUT pin, which can drive a shuntterminated bandpass filter over a large dynamic range.
MIXOUT can drive a shunt-terminated 330Ω filter (165Ω
load) to more than 2Vp-p over the entire supply range.
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
as possible for lowest phase noise. The tank’s PC board
layout is also critical to good performance (consult the
Layout Issues section for more information).
The OSCOUT pin buffers the internal oscillator signal
for driving an external PLL. This output should be AC
coupled and terminated at the far end (typically the
input to a prescaler) with a 50Ω load. If a larger output
level is desired, you can use a resistive termination up
to 100Ω. When a controlled-impedance PC board is
used, this trace’s impedance should match the termination impedance.
Power Management
The MAX2511 features four power-supply modes to preserve battery life. These modes are selected via the
RXEN and TXEN pins, according to Table 1.
In shutdown mode, all part functions are off. In standby
mode, the LO and the LO buffer are active. This allows
a PLL (implemented externally to the MAX2511) to
remain up and running, avoiding any delay resulting
from PLL loop settling. Transmit (Tx) mode enables the
LO circuitry, upconverter mixer, transmit VGA, and output driver amplifier. Receive (Rx) mode enables the LO
circuitry, downconverter mixer, limiting amplifier, and
adjustable output level amplifier.
Table 1. Power-Supply Mode Selection
RXEN
STATE
TXEN
STATE
MODE
Low
Low
Shutdown
Transmit
Low
High
High
Low
Receive
High
High
Standby
__________Applications Information
400MHz ISM Applications
The MAX2511 can be used in applications where the
200MHz to 440MHz signal is an RF (rather than an IF)
signal, such as in 400MHz ISM applications. In this
case, we recommend preceding the MAX2511 receiver
section with a low-noise amplifier (LNA) that can operate over the same supply-voltage range. The
MAX2630–MAX2633 family of amplifiers meets this
requirement. But since these parts have single-ended
inputs and outputs, it is necessary to AC terminate the
unused MAX2511 input (RXIN) to ground with 47nF.
12
Oscillator Tank
The on-chip oscillator circuit requires a parallel resonant tank circuit connected across TANK and TANK.
Figure 3 shows an example of an oscillator tank circuit.
Inductor L1 is resonated with the effective total capacitance of C1 in parallel with the series combination of
C2, C3, and (CD1) / 2. CD1 is the capacitance of one
of the varactor diodes. Typically, C2 = C3 to maintain
symmetry. The effective parasitic capacitance, CP
(including PCB parasitics), is approximately 3.5pF. The
total capacitance is given by the following equation:
CEFF =
1
+ C1 + CP
2
2
+
C2
CD1
Using this value for the resonant tank circuit, the oscillation frequency is as follows:
1
FOSC =
L1CEFF
2πEquation.2
EMBED
Starting with the inductor recommended in Table 2,
choose the component values according to your application needs, such as phase noise, tuning range, and
VCO gain. Keep the tank’s Q as high as possible to
reduce phase noise. For most of the MAX2511’s applications (such as a first IF to second IF transceiver), the
oscillator’s tuning range can be quite small, since the IF
frequencies are not tuned for channel selection. This
allows a narrowband oscillator tank to be used, which
typically provides better phase noise and stability performance than wideband tank circuits. Careful PC
board layout of the oscillator tank is essential. See the
Layout Issues section for more information.
To overdrive the oscillator from an external 50Ω source,
see Figure 4.
Rx Input Impedance Matching
The RXIN, RXIN port typically needs an impedancematching network for proper connection to external circuitry such as a filter. See the Typical Operating Circuit
for an example circuit topology. A shunt resistor across
RXIN, RXIN can be used to set terminating impedance,
with a slight degradation of the Noise Figure.
The component values used in the matching network
depend on the desired operating frequency as well as
the filter impedance. Table 3 indicates the RXIN, RXIN
differential input impedance in both series and parallel
form. This data is also plotted in the Typical Operating
Characteristics.
______________________________________________________________________________________
Low-Voltage IF Transceiver
with Limiter and RSSI
Receive IF Filter
The interstage 10.7MHz filter, located between the
MIXOUT pin and the LIMIN pin, is not shared. This filter
prevents the limiter from acting on any undesired signals that are present at the mixer’s output, such as LO
feedthrough, out-of-band channel leakage, and other
mixer products. This filter is also set up to pass DC bias
voltage from the the V REF pin into the LIMIN and
MIXOUT pins through two filter-termination resistors
(330Ω—see the Typical Operating Circuit for more
information). If the filter can provide a DC shunt path,
such as a transformer-capacitor based filter or some L-C
filters, the two resistors can be combined into one parallel, equivalent resistor (165Ω) to reduce component
count (Figure 5—inset).
______________________Layout Issues
A well-designed PC board is an essential part of an RF
circuit. For best performance, pay attention to powersupply issues, as well as the layout of the matching networks and tank circuit.
Power-Supply Layout
For minimizing coupling between different sections of the
chip, the ideal power-supply layout is a star configuration, which has a heavily decoupled central VCC node.
The VCC traces branch out from this node, each going to
one VCC node on the MAX2511. At the end of each of
these traces is a bypass capacitor that is good at the
RF frequency of interest. This arrangement provides
local decoupling at each VCC pin. At high frequency,
any signal leaking from a supply pin sees a relatively
high impedance (formed by the VCC trace impedance)
to the central VCC node, and an even higher impedance to any other supply pin.
Place the VREF decoupling capacitor (0.1µF typ) as
close to the MAX2511 as possible for best interstage filter performance. Use a high-quality, low-ESR capacitor
for best results.
Matching Network Layout
The TXOUT, TXOUT port requires a bias network that
consists of two inductors to VCC (for differential drive)
and optionally a back-termination resistor for matching
to an external filter. The RXIN, RXIN port also needs an
impedance-matching network. Both networks should be
symmetrical and as close to the chip as possible. See
the Typical Operating Circuit for more details. If you use
a ground-plane PC board, cut out the ground plane
under the matching network components to reduce
parasitic capacitance.
Local-Oscillator Tank Layout
Oscillator-tank circuit layout is critical. Parasitic PC
board capacitance, as well as trace inductance, can
affect oscillation frequency. Keep the tank layout symmetrical, tightly packed, and as close to the device as
possible. If a ground-plane PC board is used, the
ground plane should be cut out under the oscillator
components to reduce parasitic capacitance.
______________________________________________________________________________________
13
MAX2511
Filter Sharing
In half-duplex or TDD applications, the number of external filters can be minimized by combining transmit and
receive filter paths (Figure 5).
The 10.7MHz filter that is usually connected to the
TXIN, TXIN ports can be the same filter that is connected at LIMOUT and LIMOUT. To use the same filter, connect TXIN to LIMOUT, and TXIN to LIMOUT.
The 425MHz SAW filter needed at the RXIN, RXIN ports
and the filter needed at TXOUT and TXOUT can be
shared in a similar manner. The RXIN, RXIN ports must
be DC blocked to prevent the bias voltage needed by
the TXOUT and TXOUT pins from entering the receiver.
When sharing filters in this manner, the transmitter output port (TXOUT, TXOUT) and receiver input port (RXIN,
RXIN) matching networks must be modified. The receiver port’s input impedance must be the parallel combination of the receiver and transmitter ports in Rx mode.
In this case, the receiver port is active, but the transmitter port adds an additional parasitic impedance. See
the transmitter and receiver-port impedance graphs in
the Typical Operating Characteristics.
When the part is in transmit mode, the RXIN and RXIN
inputs provide back termination for the TXOUT and
TXOUT outputs so that a single IF filter can be connected (Figure 5). With this technique, the matching network
can be adjusted so the input VSWR is less than 1.5:1 in
Rx mode, and the output VSWR is less than 2:1 in Tx
mode.
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
10k
TANK
C2
10k
CP
L1
VCO VOLTAGE
FROM PLL
C1
C3
TANK
10k
C2 = C3
Figure 3. Oscillator Tank Schematic
TANK
MINI CIRCUITS
TC4-1Ω
50Ω
SIGNAL SOURCE
R = 200Ω
CP
TANK
ADJUST R FOR BEST RETURN LOSS AT SIGNAL SOURCE
Figure 4. Overdriving the On-Chip Oscillator
Table 2. Recommended Values for L1
14
fLO (MHz)
L1 (µH)
200 to 300
18
300 to 400
12
400 to 500
8.2
Table 3. Rx Input Impedance
FREQUENCY
(MHz)
SERIES
IMPEDANCE
(Ω)
EQUIVALENT PARALLEL
IMPEDANCE
R (Ω)
C (pF)
100
274-j226
460
2.85
200
131-j186
395
2.86
300
79-j138
320
2.9
400
58-j105
248
2.9
500
48-j82
188
2.9
600
43-j62
132
2.9
______________________________________________________________________________________
Low-Voltage IF Transceiver
with Limiter and RSSI
MAX2511
ONE PORT FILTER
(LC OR TRANSFORMER-C)
TWO-PORT FILTER
10.7 MHz BPF
165Ω
0.1µF
330Ω
MIXOUT
VREF
330Ω
LIMIN
0.1µF
MIXOUT
LIMIN
RXIN
ROPT
VCC
LIMOUT
RX
MIXER
VREF
LIMITER
LIMOUT
VCC
RXIN
LMATCH
LMATCH
CBLOCK CBLOCK
MAX2511
TXOUT
TXIN
CMATCH
TXOUT
10.7MHz
BPF
TX
MIXER
TXIN
425MHz
BPF
CMATCH
CONTROL
GC
Figure 5. Filter Sharing
______________________________________________________________________________________
15
MAX2511
Low-Voltage IF Transceiver
with Limiter and RSSI
___________________________________________________Typical Operating Circuit
VCC
VCC
47nF
LCHOKE
47nF
LCHOKE
24
1k
TXOUT
TXIN
CBLOCK
Tx
OUTPUT
TXIN
R*
23
LIMOUT
TXOUT
LIMOUT
CBLOCK
25
RXIN
RXEN
CMATCH
Rx
INPUT
LMATCH
TXEN
CMATCH
MAX2511
22
1k
10.7MHz Tx
0.1µF
15
INPUT
0.1µF
13
10.7MHz Rx
0.1µF
14
IF OUTPUT
18
CONTROL
LOGIC
17
VCC
VCC
8
GND
7
TANK
6
RXIN
VCC
47nF
VCC
20
21
47nF
VCC
6.8pF
10kΩ
D1
8.2nH
20
GND
TANK
4
5
FOSC = 435.7MHz
VCC
47nF
100pF
0.1µF
16
10kΩ
12pF
VCO ADJUST
FROM PLL
10kΩ
9
6.8 pF
RSSI
470pF
OSCOUT
GC
12
TO PRESCALER
VCC
26
0.01µF*
27
VCC
GND
GND
MIXOUT
LIMIN
10.7MHz
BPF, Z0 = 330Ω
1
330Ω
330Ω
0.1µF
CZ
VREF CZ
28
11
10
D1 = ALPHA SMV1204-199
47nF
3
2
0.01µF
GAIN CONTROL VOLTAGE
RSSI OUTPUT
*OPTIONAL
16
______________________________________________________________________________________
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