Preliminary Data Sheet
November 1998
W3013 Indirect Quadrature Modulator
with Gain Control
Application Circuits
A typical application circuit for the W3013 is shown in Figure 4. The LC filter components, L
F
and C
F
, are chosen
to have a parallel resonance at the same frequency as LO1, according to the formula
f
O
=
1
2
L
F
(C
F
+
1.2e
−
12)
where f
O
is the center of the filter passband in Hz, L
F
is the filter inductor in Henries, and C
F
is the filter capacitor
in farads. Use of an inductor of 100 nH or larger in the filter will minimize the variation of output power due to
tolerance variation of the filter components.
If the transmitter frequency plan requires the use of more than one LO1 frequency, the W3013 RF output power
may be approximately equalized by designing the LC filter center frequency at
f
O
=
f(LO1max)f(LO1min)
,
i.e., the geometric mean of the maximum and minimum LO1 frequencies.
Board and device parasitic capacitance and inductance must be accounted for in calculating L
F
and C
F
.
The matching network will vary depending on the application, but must include a series capacitor to block dc
connections to the W3013 output pin if the load is conductive. For optimum performance, the bypass capacitor,
C
1
, should have a series self-resonant frequency that is close to the output frequency and should be mounted
near pin 20. It is expected that the positive supply (V
CC
) will appear as a low impedance to ground at low
frequencies, using a voltage regulator and/or a large capacitor such as a 10
µF
tantalum electrolytic.
+2.7 V
C1
MATCHING
NETWORK
1
L
F
20
19
18
17
16
15
14
13
12
11
50
Ω
(OPT)
LO2
ENB/APC
z
2
3
4
5
6
7
8
LO1
9
50
Ω
(OPT)
10
z
OUTPUT
C
F
I
I
Q
Q
SIGNALS
FROM CODEC
Figure 4. Typical Application Circuit
Lucent Technologies Inc.
7
AGERE [ AGERE SYSTEMS ]
