IAM-91563-TR1 Avago Technologies US Inc., IAM-91563-TR1 Datasheet - Page 8

• Manufacturer Part Number: IAM-91563-TR1
• Description: IC,Downconverter,GAAS,TSSOP,6PIN,PLASTIC
• Manufacturer: Avago Technologies US Inc.

Specifications of IAM-91563-TR1

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

microstriplines on PC boards in this thickness range is
also very convenient for mounting chip components
such as the series inductor at the input or DC blocking
and bypass capacitors.
For applications using higher frequencies such as the
5.8 GHz ISM band, the additional cost of PTFE/glass
dielectric materials may be warranted to minimize
transmission line loss at the mixer’s RF input. An
additional consideration of using lower cost materials
at higher frequencies is the degradation in the Q’s of
transmission lines used for impedance matching.
Biasing
The IAM-91563 is a voltage-biased device and is de-
signed to operate in the “normal mode” from a single,
+3 volt power supply with a typical current drain of
only 9 mA. The internal current regulation circuit al-
lows the mixer to be operated with voltages as high as
+5 volts or as low as +1.5 volt.
The device current can be increased up to 20 mA by
adding an external resistor from the Source Bypass pin
to ground. This feature makes it possible to operate the
IAM-91563 in the “high power mode” to achieve greater
linearity. Refer to the section titled “High Linearity
Mode” for information on applications and perfor-
mance when using this feature.
Application Guidelines
Several design considerations should be taken into
account to ensure that maximum performance is ob-
tained from the IAM-91563 downconverter. The RF and
IF ports must be impedance matched at their respec-
tive frequencies to the circuits to which they are con-
nected. This is typically 50 ohms when the mixer is
used as a building block component in a 50-ohm sys-
tem. These ports have been left untuned on the MMIC
to allow the mixer to be used over a wide range of RF
and IF bands. The LO port is already sufficiently well
matched (less than 1 dB of mismatch loss) for most
applications.
As with most mixers, appropriate filters must be placed
at the RF port and IF port such as in Figure 22. The filter
in front of the RF port eliminates interference from the
image frequency and the IF filter prevents RF and LO
signal leakage into the IF signal processing circuitry.
Figure 22. Image and IF Filters.
HP Filter
RF
LO
IF
LP Filter
Additional design considerations relate to the use of
higher bias current where greater linearity is required,
bypassing of the Source Bypass pin, bias injection, and
DC blocking and bypassing.
Each of these design factors will be discussed in greater
detail in the following sections.
RF Port
A well matched RF port is especially important to
maximize the conversion gain of the IAM-91563 mixer.
Matching is also necessary to realize the specified
noise figure and RF-to-LO isolation. The amount the
conversion gain can be increased by impedance match-
ing is equal to the mismatch loss at the RF port. The
impedance of the RF port is characterized by the
measured reflection coefficients shown in Typical Re-
flection Coefficients Table. The maximum “mismatch
gain” that results from eliminating the mismatch loss is
expressed in dB as a function of the reflection coeffi-
cient as:
For wireless bands in the 800 MHz to 6 GHz range, the
magnitude of the reflection coefficient of the RF port
varies from 0.91 to 0.80, which corresponds to a mis-
match gain of 7.6 to 4.4 dB.
The impedance of the RF port is capacitive, and for
frequencies from 800 MHz to 2.4 GHz, falls very near
the R=1 circle of a Smith chart. While these imped-
ances could be easily matched to 50 ohms with a simple
series inductor, it is advantageous to use a 2-element
matching network of the series C, shunt L type as
shown in Figure 23 instead. There are two main rea-
sons for this choice. The first is to incorporate a high
pass filter characteristic into the matching circuit.
Second, the series C, shunt L combination will match
the entire range of RF port impedances to 50 Ω. Most
wireless communication bands are sufficiently narrow
that a single (mid-band) frequency approach to imped-
ance matching is adequate.
Figure 23. RF Input HPF Matching.
Input
RF
G
RF, mm
C
= 10 log
L
8
RF
10
1– Γ
1
RF
LO
2
IF
(1)