IAM-91563-TR1 Avago Technologies US Inc., IAM-91563-TR1 Datasheet - Page 11

• 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

Figure 30. RF Input Impedance Match.
For this example, the shunt inductor was realized with
the transmission line, MLIN in Figure 29 (Z
length = 0.35 in.). A high quality capacitor should be
selected for C1 to minimize the effects of the capacitor’s
parasitic inductance and resistance. Series capacitor
C1 also serves to block any DC that may be present at
the output of the stage preceding the mixer.
At the IF output, the low pass filter and impedance
match is formed by shunt capacitor C2 and series induc-
tor L2. Referring again to the table of Reflection Coeffi-
cients, the IF output port Γ
which is the frequency point closest to the desired IF of
110 MHz. Γ
Figure 31. IF Input Impedance Match.
-0.2
-0.2
0.2
0.2
IF
is plotted as Point A in Figure 31.
0.2
0.2
-0.5
-0.5
0.5
0.5
Input
C
RF
0.5
0.5
C1
B
C2
L
A
A
C
C
1
1
-1
IF
-1
1
1
B
L2
= 0.64 ∠ -8° at 100 MHz,
Output
C
IF
2
2
B
A
B
2
2
-2
-2
A
O
= 90Ω,
Adding a shunt capacitance (C2) of 11.3 pF brings the
impedance to Point B. The match to Point C at the
center of the chart is completed with a series induc-
tance (L2) of 150 nH.
Although not necessary for many applications, the
match at the LO port can be improved by the addition
of series inductor L3 with a value of approximately
8 nH. Design information (Γ
port is obtained from the table of Reflection Coeffi-
cients. Capacitor C7 is a DC block for the LO port.
DC bias is applied to the IAM-91563 through the RFC at
the IF Output pin. The power supply is bypassed to
ground with capacitor C5 to keep RF, IF, and LO signals
off of the DC bias lines and to prevent gain dips or peaks
in the response of the mixer. C4 is a DC blocking
capacitor for the output.
The values of the RF bypass capacitors and DC block-
ing capacitors that are not part of a impedance match-
ing structure (i.e., C3 - C7) should be chosen to provide
a small reactance (typically < 5 ohms) at the lowest
frequency at the port for which they are used. The
reactance of the RF choke (RFC) should be high (e.g.,
several hundred ohms) at the lowest IF.
The completed 1.9 GHz mixer from the design example
above with all components and SMA connectors in
place is shown in Figure 32. Again, L1 is not used and
is replaced by a metal tab. The length of the shunt
transmission line, MLIN, is adjustable by moving the
position of the shorting tab between the line and the
ground pad. Provision is made for an additional bypass
capacitor, C6, to be added to the bias line near the V
connection to eliminate unwanted RF feedback through
bias lines.
When multiple bypass capacitors are used, consider-
ation should be given to potential resonances. It is
important to ensure that the capacitors, when com-
bined with additional parasitic L’s and C’s on the circuit
board, do not form resonant circuits. The addition of a
small value resistor in the bias supply line between
bypass capacitors will often “de-Q” the bias circuit and
eliminate resonance effects.
11
LO
) for matching the LO
d