The MAX19998 single, high-linearity downconversion
mixer provides 8.7dB of conversion gain, +24.3dBm
input IP3, +11.3dBm 1dB input compression point,
and a noise figure of 9.7dB for 2300MHz to 4000MHz
WiMAXK, LTE, and MMDS receiver applications. With
an ultra-wide LO 2600MHz to 4300MHz frequency
range, the MAX19998 can be used in either low-side
or high-side LO injection architectures for virtually all
2.5GHz and 3.5GHz applications. For a 2.5GHz variant tuned specifically for high-side injection, refer to the
MAX19996A.
In addition to offering excellent linearity and noise performance, the MAX19998 also yields a high level of
component integration. This device includes a doublebalanced passive mixer core, an IF amplifier, and an LO
buffer. On-chip baluns are also integrated to allow for
single-ended RF and LO inputs. The MAX19998 requires
a nominal LO drive of 0dBm, and supply current is typically 230mA at VCC = 5.0V or 150mA at VCC = 3.3V.
The MAX19998 is pin compatible with the MAX19996/
MAX19996A 2000MHz to 3900MHz mixer family. The
device is also pin similar with the MAX9984/MAX9986/
MAX9986A 400MHz to 1000MHz mixers and the
MAX9993/MAX9994/MAX9996 1700MHz to 2200MHz
mixers, making this entire family of downconverters ideal
for applications where a common PCB layout is used for
multiple frequency bands.
The MAX19998 is available in a compact, 5mm x 5mm,
20-pin thin QFN with an exposed pad. Electrical performance is guaranteed over the extended -40NC to +85NC
temperature range.
Applications
2.5GHz WiMAX and LTE Base Stations
2.7GHz MMDS Base Stations
3.5GHz WiMAX and LTE Base Stations
Fixed Broadband Wireless Access
Wireless Local Loop
Private Mobile Radios
Military Systems
Features
S2300MHz to 4000MHz RF Frequency Range
S2600MHz to 4300MHz LO Frequency Range
S50MHz to 500MHz IF Frequency Range
S8.7dB Conversion Gain
S9.7dB Noise Figure
S+24.3dBm Typical Input IP3
S+11.3dBm Typical Input 1dB Compression Point
S67dBc Typical 2RF - 2LO Spurious Rejection at
PRF = -10dBm
SIntegrated LO Buffer
SIntegrated RF and LO Baluns for Single-Ended
Inputs
SLow -3dBm to +3dBm LO Drive
SPin Compatible with the MAX19996/MAX19996A
2000MHz to 3900MHz Mixers
SPin Similar with the MAX9984/MAX9986/
MAX9986A Series of 400MHz to 1000MHz Mixers
and the MAX9993/MAX9994/MAX9996 Series of
1700MHz to 2200MHz Mixers
SSingle 5.0V or 3.3V Supply
SExternal Current-Setting Resistors Provide Option
for Operating Device in Reduced-Power/ReducedPerformance Mode
Ordering Information
PARTTEMP RANGEPIN-PACKAGE
MAX19998ETP+
MAX19998ETP+T
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..........................................................-0.3V to +5.5V
IF+, IF-, LOBIAS, IFBIAS to GND ............. -0.3V to (VCC + 0.3V)
RF, LO Input Power .......................................................+12dBm
RF, LO Current
(RF and LO is DC shorted to GND through balun) ........50mA
Continuous Power Dissipation (Note 1) ................................. 5W
Note 1: Based on junction temperature TJ = TC + (BJC x VCC x ICC). This formula can be used when the temperature of the
MAX19998
Note 2: Junction temperature TJ = TA + (BJA x VCC x ICC). This formula can be used when the ambient temperature of the PCB is
Note 3: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
Note 4: TC is the temperature on the exposed pad of the package. TA is the ambient temperature of the device and PCB.
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.
exposed pad is known while the device is soldered down to a PCB. See the Applications Information section for details.
The junction temperature must not exceed +150NC.
known. The junction temperature must not exceed +150NC.
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
5.0V SUPPLY DC ELECTRICAL CHARACTERISTICS
(Typical Application Circuit,R1 = 698ω, R2 = 604ω, VCC = 4.75V to 5.25V, no input RF or LO signals. TC = -40NC to +85NC, unless
otherwise noted. Typical values are at VCC = 5.0V, TC = +25NC, all parameters are production tested.)
Using a Mini-Circuits TC4-1W-17 4:1
transformer as defined in the Typical Application Circuit, IF matching components
affect the IF frequency range (Notes 5, 6)
IF
Using a Mini-Circuits TC4-1W-7A 4:1
transformer as defined in the Typical Application Circuit, IF matching components
affect the IF frequency range (Notes 5, 6)
LO
100500
50250
-30+3dBm
MHz
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
5.0V SUPPLY AC ELECTRICAL CHARACTERISTICS—fRF = 3100MHz to 3900MHz,
LOW-SIDE LO INJECTION
(Typical Application Circuit, with tuning elements outlined in Table 1, R1 = 698ω, R2 = 604ω, VCC = 4.75V to 5.25V, RF and LO ports
are driven from 50I sources, PLO = -3dBm to +3dBm, PRF = -5dBm, fRF = 3100MHz to 3900MHz, fIF = 300MHz, fLO = 2800MHz to
3600MHz, fRF > fLO, TC = -40NC to +85NC. Typical values are for TC = +25NC, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, fRF = 3500MHz,
fLO = 3200MHz, fIF = 300MHz. All parameters are guaranteed by design and characterization, unless otherwise noted.) (Note 7)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Small-Signal Conversion GainG
Gain Variation vs. Frequency
Conversion Gain Temperature
Coefficient
Input 1dB Compression PointIP
Third-Order Input Intercept PointIIP3
IIP3 Variation with T
Single-Sideband Noise FigureNF
Noise Figure Temperature
Coefficient
Noise Figure Under BlockingNF
2RF - 2LO Spur Rejection2 x 2f
3RF - 3LO Spur Rejection3 x 3f
RF Input Return LossRL
LO Input Return LossRL
IF Output ImpedanceZ
IF Output Return LossRL
C
DG
TC
TC
C
C
CG
1dB
SSB
NF
B
RF
LO
IF
IF
TC = +25NC (Notes 8, 9)
fRF = 3100MHz to 3900MHz, any 100MHz
band
fRF = 3100MHz to 3900MHz, any 200MHz
band
fRF = 3100MHz to 3900MHz,
TC = -40NC to +85NC
(Note 10)10.011.4dBm
f
- f
RF1
TC = +25NC (Note 9)
fRF = 3100MHz to 3900MHz, f
P
RF1
No blockers present (Note 5)9.712.5
No blockers present, TC = +25NC (Note 5)
Single sideband, no blockers present,
TC = -40NC to +85NC
+8dBm blocker tone applied to RF port,
fRF = 3500MHz, fLO = 3200MHz,
f
BLOCKER
VCC = +5.0V, TC = +25NC (Notes 5, 11)
SPUR
SPUR
LO on and IF terminated into a matched
impedance
RF and IF terminated into a matched
impedance
Nominal differential impedance at the IC’s IF
outputs
RF terminated into 50I, LO
driven by 50I source, IF
transformed to 50I using
external components shown
in the Typical Application
Circuit. See the Typical
Operating Characteristics
3.3V SUPPLY AC ELECTRICAL CHARACTERISTICS—fRF = 3100MHz to 3900MHz,
LOW-SIDE LO INJECTION (continued)
(Typical Application Circuit, with tuning elements outlined in Table 1, R1 = 845ω, R2 = 1.1kω, RF and LO ports are driven from 50I
sources, fRF > fLO. Typical values are for TC = +25NC, VCC = 3.3V, PRF = -5dBm, PLO = 0dBm, fRF = 3500MHz, fLO = 3200MHz, fIF
= 300MHz, unless otherwise noted.) (Note 7)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
RF terminated into 50I, LO
driven by 50I source, IF
transformed to 50I using
external components shown
IF Output Return LossRL
RF-to-IF IsolationfRF = 3100MHz to 3900MHz, PLO = +3dBm27dB
LO Leakage at RF PortfLO = 2800MHz to 3600MHz, PLO = +3dBm-30dBm
2LO Leakage at RF PortfLO = 2800MHz to 3600MHz, PLO = +3dBm-26.5dBm
LO Leakage at IF PortfLO = 2800MHz to 3600MHz, PLO = +3dBm-27.5dBm
in the Typical Application
IF
Circuit. See the Typical
Operating Characteristics
for performance vs. inductor
values.
5.0V SUPPLY AC ELECTRICAL CHARACTERISTICS—fRF = 3100MHz to 3900MHz,
HIGH-SIDE LO INJECTION
(Typical Application Circuit, with tuning elements outlined in Table 1, R1 = 698ω, R2 = 604ω, VCC = 4.75V to 5.25V, RF and LO ports
are driven from 50I sources, PLO = -3dBm to +3dBm, PRF = -5dBm, fRF = 3100MHz to 3900MHz, fIF = 300MHz, fLO = 3400MHz
to 4200MHz, fRF < fLO, TC = -40NC to +85NC. Typical values are for TC = +25NC, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, fRF =
3500MHz, fLO = 3800MHz, fIF = 300MHz, unless otherwise noted.) (Note 7)
5.0V SUPPLY AC ELECTRICAL CHARACTERISTICS—fRF = 2300MHz to 2900MHz,
HIGH-SIDE LO INJECTION (continued)
(Typical Application Circuit, with tuning elements outlined in Table 1, R1 = 698ω, R2 = 604ω, VCC = 4.75V to 5.25V, RF and LO ports
are driven from 50I sources, PLO = -3dBm to +3dBm, PRF = -5dBm, fRF = 2300MHz to 2900MHz, fIF = 300MHz, fLO = 2600MHz
to 3200MHz, fRF < fLO, TC = -40NC to +85NC. Typical values are for TC = +25NC, VCC = 5.0V, PRF = -5dBm, PLO = 0dBm, fRF =
2600MHz, fLO = 2900MHz, fIF = 300MHz, unless otherwise noted. (Note 7)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
IIP3 Variation with T
Single-Sideband Noise FigureNF
Noise Figure Temperature
Coefficient
2LO - 2RF Spur Rejection2 x 2f
3LO - 3RF Spur Rejection3 x 3f
RF Input Return LossRL
LO Input Return LossRL
IF Output ImpedanceZ
IF Output Return LossRL
C
SSB
TC
NF
RF
LO
IF
IF
fRF = 2300MHz to 2900MHz, f
P
= P
RF1
No blockers present 10.0dB
Single sideband, no blockers present,
TC = -40NC to +85NC
SPUR
SPUR
LO on and IF terminated into a matched
impedance
RF and IF terminated into a matched
impedance
Nominal differential impedance at the IC’s IF
outputs
RF terminated into 50I,
LO driven by 50I source,
IF transformed to 50I
using external components shown in the Typical Application Circuit. See
the Typical Operating Characteristics for performance vs. inductor values.
Note 5: Not production tested.
Note 6: Operation outside this range is possible, but with degraded performance of some parameters. See the Typical
Operating Characteristics.
Note 7: All limits reflect losses of external components, including a 0.8dB loss at fIF = 300MHz due to the 4:1 impedance trans-
former. Output measurements were taken at IF outputs of the Typical Application Circuit.
Note 8: Guaranteed by design and characterization.
Note 9: 100% production tested for functional performance.
Note 10: Maximum reliable continuous input power applied to the RF port of this device is +12dBm from a 50I source.
Note 11: Measured with external LO source noise filtered so that the noise floor is -174dBm/Hz. This specification reflects the
effects of all SNR degradations in the mixer including the LO noise, as defined in Application Note 2021: Specifications
and Measurement of Local Oscillator Noise in Integrated Circuit Base Station Mixers.
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 3.3V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 3.3V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 3.3V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 3.3V, fRF = 3100MHz to 3900MHz, LO is low-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 3100MHz to 3900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 2300MHz to 2900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 2300MHz to 2900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Typical Operating Characteristics (continued)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 2300MHz to 2900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
(Typical Application Circuit with tuning elements outlined in Table 1, VCC = 5.0V, fRF = 2300MHz to 2900MHz, LO is high-side injected
for a 300MHz IF, PRF = -5dBm, PLO = 0dBm, TC = +25NC, unless otherwise noted.)
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Pin Configuration/Functional Diagram
TOP VIEW
IF+
IF-
GND
IFBIAS
19201817
LEXT
16
V
1
CC
15
GND
MAX19998
CC
V
MAX19998
9
GND
10
GND
GND
GND
GND
2
RF
3
4
EP
5
768
CC
V
LOBIAS
Pin Description
PINNAMEFUNCTION
1, 6, 8, 14V
CC
2RF
3, 9, 13, 15GNDGround. Not internally connected. Pins can be grounded.
Power Supply. Bypass to GND with 0.01FF capacitors as close as possible to the pin.
Single-Ended 50I RF Input. Internally matched and DC shorted to GND through a balun. Provide an
input DC-blocking capacitor if required.
V
14
CC
13
GND
12
GND
11
LO
4, 5, 10, 12,
17
7LOBIAS
11LO
GND
Ground. Internally connected to the exposed pad. Connect all ground pins and the exposed pad
(EP) together.
LO Amplifier Bias Control. Output bias resistor for the LO buffer. Connect a 604I (5V, 230mA bias
condition) from LOBIAS to ground.
Local Oscillator Input. This input is internally matched to 50I. Requires an input DC-blocking capacitor.
External Inductor Connection. Connect a low-ESR 4.7nH inductor from this pin to ground to increase
16LEXT
the RF-to-IF and LO-to-IF isolation. Connect this pin directly to ground to reduce the component
count at the expense of reduced RF-to-IF and LO-to-IF isolation.
18, 19IF-, IF+
20IFBIAS
Mixer Differential IF Output. Connect pullup inductors from each of these pins to VCC (see the Typical Application Circuit).
IF Amplifier Bias Control. IF bias resistor connection for the IF amplifier. Connect a 698I (5V, 230mA
bias condition) from IFBIAS to GND.
Exposed Pad. Internally connected to GND. Solder this exposed pad to a PCB pad that uses multiple
—EP
ground vias to provide heat transfer out of the device into the PCB ground planes. These multiple via
grounds are also required to achieve the noted RF performance.
The MAX19998 provides high linearity and low noise
figure for a multitude of 2300MHz to 4000MHz WiMAX,
LTE, and MMDS base-station applications. This device
operates over a 2600MHz to 4300MHz LO range and
a 50MHz to 500MHz IF range. Integrated baluns and
matching circuitry allow 50I single-ended interfaces to
the RF and LO ports. The integrated LO buffer provides a
high drive level to the mixer core, reducing the LO drive
required at the MAX19998’s input to a range of -3dBm
to +3dBm. The IF port incorporates a differential output,
which is ideal for providing enhanced 2RF - 2LO and
2LO - 2RF performance.
RF Input and Balun
The MAX19998 RF input provides a 50I match when
combined with a series DC-blocking capacitor. This
DC-blocking capacitor is required as the input is internally DC shorted to ground through the on-chip balun.
When using an 8.2pF DC-blocking capacitor, the RF port
input return loss is typically 17dB over the RF frequency
range of 3200MHz to 3900MHz. See Table 1 for lower
band tuning.
LO Inputs, Buffer, and Balun
The LO input is internally matched to 50I, requiring
only a 2pF DC-blocking capacitor. A two-stage internal
LO buffer allows for a -3dBm to +3dBm LO input power
range. The on-chip low-loss balun, along with an LO
buffer, drives the double-balanced mixer. All interfacing
and matching components from the LO inputs to the IF
outputs are integrated on-chip.
High-Linearity Mixer
The core of the MAX19998 is a double-balanced, highperformance passive mixer. Exceptional linearity is provided by the large LO swing from the on-chip LO buffer.
When combined with the integrated IF amplifier, IIP3,
2RF - 2LO rejection, and noise-figure performance are
typically +24.3dBm, 67dBc, and 9.7dB, respectively,
for low-side LO injection architectures covering the
3000MHz to 4000MHz RF band.
Differential IF Output Amplifier
The MAX19998 has a 50MHz to 500MHz IF frequency
range, where the low-end frequency depends on the
frequency response of the external IF components. The
MAX19998 mixer is tuned for a 300MHz IF using 390nH
external pullup bias inductors. Lower IF frequencies
would require higher L1 and L2 inductor values to main-
MAX19998
tain a good IF match. The differential, open-collector IF
output ports require that these inductors be connected
to VCC.
Note that these differential ports are ideal for providing enhanced 2RF - 2LO performance. Single-ended
IF applications require a 4:1 (impedance ratio) balun to
transform the 200I differential IF impedance to a 50I
single-ended system. Use the TC4-1W-17 4:1 transformer for IF frequencies above 200MHz and the TC4-1W-7A
4:1 transformer for frequencies below 200MHz. The user
can use a differential IF amplifier or SAW filter on the
mixer IF port, but a DC block is required on both IF+/
IF- ports to keep external DC from entering the IF ports
of the mixer.
Applications Information
Input and Output Matching
The RF and LO inputs provide 50I matches when
combined with the proper tuning. Use an 8.2pF capacitor value on the RF port for frequencies ranging from
3000MHz to 4000MHz. Use a 3.3nH series inductor and
a 0.3pF shunt capacitor on the RF port for frequencies
ranging from 2300MHz to 2900MHz. On the LO port, use
a 2pF DC-blocking capacitor to cover operations spanning the 2600MHz to 4300MHz range.
The IF output impedance is 200I (differential). For evaluation, an external low-loss 4:1 (impedance ratio) balun
transforms this impedance down to a 50I single-ended
output (see the Typical Application Circuit).
Reduced-Power Mode
The MAX19998 has two pins (LOBIAS, IFBIAS) that allow
external resistors to set the internal bias currents. See
Table 1 for nominal values for these resistors. Larger
value resistors can be used to reduce power dissipation at the expense of some performance loss. If Q1%
resistors are not readily available, substitute with Q5%
resistors.
Significant reductions in power consumption can also
be realized by operating the mixer with an optional
supply voltage of 3.3V. Doing so reduces the overall
power consumption by 57% (typ). See the 3.3V Supply AC Electrical Characteristics table and the relevant 3.3V
curves in the Typical Operating Characteristics section
to evaluate the power vs. performance trade-offs.
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
LEXT Inductor
Short LEXT to ground using a 0I resistor. For applications requiring improved RF-to-IF and LO-to-IF isolation,
L3 can be changed to optimize performance (see the
Typical Operating Characteristics). However, the load
impedance presented to the mixer must be such that any
capacitances from IF- and IF+ to ground do not exceed
several picofarads to ensure stable operating conditions.
Since approximately 120mA flows through LEXT, it is
MAX19998
important to use a low-DCR wire-wound inductor.
Layout Considerations
A properly designed PCB is an essential part of any RF/
microwave circuit. Keep RF signal lines as short as possible to reduce losses, radiation, and inductance. The
load impedance presented to the mixer must be such
that any capacitance from both IF- and IF+ to ground
does not exceed several picofarads. For the best performance, route the ground pin traces directly to the
exposed pad under the package. The PCB exposed pad
MUST be connected to the ground plane of the PCB. It is
suggested that multiple vias be used to connect this pad
to the lower level ground planes. This method provides a
good RF/thermal-conduction path for the device. Solder
the exposed pad on the bottom of the device package
to the PCB. The MAX19998 evaluation kit can be used
as a reference for board layout. Gerber files are available
upon request at www.maxim-ic.com.
Power-Supply Bypassing
Proper voltage supply bypassing is essential for highfrequency circuit stability. Bypass each VCC pin with the
capacitors shown in the Typical Application Circuit and
see Table 1 for component values.
Table 1. Component Values
DESIGNATIONQTYDESCRIPTIONCOMPONENT SUPPLIER
8.2pF microwave capacitor (0402). Use for RF
C11
C2, C6, C8, C114
C3, C90Not installed, capacitors—
C1012pF microwave capacitor (0402)Murata Electronics North America, Inc.
C13, C1421000pF microwave capacitors (0402)Murata Electronics North America, Inc.
C15182pF microwave capacitor (0402)Murata Electronics North America, Inc.
C161
L1, L22390nH wire-wound high-Q inductors* (0805)Coilcraft, Inc.
L314.7nH wire-wound high-Q inductor (0603)Coilcraft, Inc.
R11
R21
R31
T114:1 IF balun TC4-1W-17*Mini-Circuits
U11MAX19998 IC (20 Thin QFN-EP)Maxim Integrated Products, Inc.
*Use larger value inductors and a TC4-1W-7A 4:1 balun for IF frequencies below 200MHz.
frequencies ranging from 3000MHz to 4000MHz.
3.3nH microwave inductor (0402). Use for RF
frequencies ranging from 2300MHz to 2900MHz.
0.01FF microwave capacitors (0402)
Not installed for RF frequencies ranging from
3000MHz to 4000MHz
0.3pF microwave capacitor (0402). Use for RF
frequencies ranging from 2300MHz to 2900MHz.
698IQ1% resistor (0402). Use for VCC = 5.0V
applications.
845IQ1% resistor (0402). Use for VCC = 3.3V
applications.
604IQ1% resistor (0402). Use for VCC = 5.0V
applications.
1.1kIQ1% resistor (0402). Use for VCC = 3.3V
applications.
The exposed pad (EP) of the MAX19998’s 20-pin thin
QFN-EP package provides a low thermal-resistance
path to the die. It is important that the PCB on which
the MAX19998 is mounted be designed to conduct
Typical Application Circuit
L1
C13
V
GND
L2
R1
IF+
IFBIAS
19201817
CC
1
RF
2
3
INPUT
RF
R3
C14
+5.0V
C3C2
C1
C16*
heat from the EP. In addition, provide the EP with a lowinductance path to electrical ground. The EP MUST be
soldered to a ground plane on the PCB, either directly or
through an array of plated via holes.
C15
326
14
4:1
IF-
GND
LEXT
16
U1
MAX19998
IF
OUTPUT
T1
L3
GND
15
V
CC
14
GND
13
+5.0V
C11
MAX19998
GND
GND
4
5
+5.0V
EP
CC
V
C6
768
CC
V
LOBIAS
R2
C8C9
9
10
GND
GND
NOTE: PINS 4, 5, 10, 12, AND 17 ARE ALL INTERNALLY
CONNECTED TO THE EXPOSED GROUND PAD. CONNECT
THESE PINS TO GROUND TO IMPROVE ISOLATION.
+5.0V
PINS 3, 9, 13, AND 15 HAVE NO INTERNAL CONNECTION, BUT CAN BE
EXTERNALLY GROUNDED TO IMPROVE ISOLATION.
*C16 NOT USED FOR 3000MHz TO 4000MHz APPLICATIONS.
SiGe, High-Linearity, 2300MHz to 4000MHz
Downconversion Mixer with LO Buffer
Chip Information
PROCESS: SiGe BiCMOS
MAX19998
Package Information
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPEPACKAGE CODEDOCUMENT NO.
20 Thin QFN-EPT2055+3
21-0140
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time.
28 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600