7-56
Figure 1. HPMX-2005 Connections Showing Unbalanced 
LO and I/Q Inputs.
Figure 2. HPMX-2005 Connections Showing Differential 
LO and I/Q Inputs.
HPMX-2005 Pin 
Descriptions
VCC (pins 1, 2 & 16)
These three pins provide DC 
power to the RFIC, and are connected together internal to the 
package. They should be connected to a 5 V supply, with appropriate AC bypassing (1000 pF 
typ.) used near the pins, as shown 
in figures 1 and 2.The voltage on
these pins should always be 
kept at least 0.8 V more posi- 
tive  than the DC level on any 
of pins 5, 6, 11, or 12. Failure to
do so may result in the modulator 
drawing sufficient current 
through the data or reference inputs to damage the IC (see also 
Figure 5).
Ground (pins 3, 4, 10, 13 & 14)
These pins should connect with 
minimal inductance to a solid 
ground plane (usually the backside of the PC board). Recommended assembly employs 
multiple plated through via holes 
where these leads contact the PC 
board.
I
ref
 (pin 12) and Q
ref
 (pin 5)
I
mod
 (pin 11) and Q
mod
 (pin 6)
Inputs
The I and Q inputs are designed 
for unbalanced operation but can 
be driven differentially with similar performance. The recommended level of unbalanced I and
Q signals is 1.5 V
p-p
 with an average level of 2.5 V above ground. 
The reference pins should be DC 
biased to this average data signal 
level (VCC/2 or 2.5 V typ.). For 
single ended drive, pins 5 and 12 
can be tied together. For differential operation, 0.75 V
p-p
 signals
may be applied across the I
mod/Iref
and the Q
mod/Qref
 pairs. The average level of all four signals should 
be about 2.5 V above ground. The 
impedance between Iin or Qin and 
ground is typically 10 kΩ and the 
impedance between I
mod
 and I
ref
or Q
mod
 and Q
ref 
 is typically
10␣ k Ω. The input bandwidth typically exceeds 40 MHz. It is possible to reduce LO leakage 
through the IC by applying slight 
DC imbalances between I
mod
 and
I
ref
 and/or Q
mod
 and Q
ref
 (see page
9). All performance data shown 
on this data sheet was taken with 
unbalanced I/Q inputs.
LO Input (pins 7 and 8)
The LO input of the HPMX-2005 is 
balanced (differential) and 
matched to 50 Ω. For drive from a 
unbalanced LO, pin 7 should be 
AC coupled to the LO using a 50 Ω 
transmission line and a blocking 
capacitor (1000 pF typ.), and pin 8 
should be AC grounded (1000 pF 
capactitor typ.), as shown in figure 1. For drive from a differential 
LO source, 50 Ω transmission 
lines and blocking capacitors 
(1000 pF typ.) are used on both
pins 7 and 8, as shown in figure 2. 
The internal phase shifter allows 
operation from 25 to 200 MHz (or 
to 250 MHz by using pin 9 — see 
below). The recommended LO 
input level is -12 dBm. All performance data shown on this data 
sheet was taken with unbalanced 
LO operation.
Phase Adjust (pin 9)
Applying a DC bias to this pin alters the frequency range of the internal RC phase shifter. In normal 
operation, this pin is not connected. (Do not ground this pin!) 
For operation at LO frequencies 
above 140 MHz, superior modulation error can be achieved by connecting pin 9 to VCC (5 V). The 
resulting changes in performance 
are shown in figures 13 through
18. Use of pin 9 extends the 
operating range to beyond 
250␣ MHz.
RF Output (pin 15)
The RF output of the HPMX-2005 
is configured for unbalanced operation, and connects directly to 
an emitter follower in the output 
stage of the IC. The output impedance is appropriate for connection 
without further impedance matching to transmission lines of 
characteristic impedance between 
50 Ω and 150 Ω. The reflection 
coefficients are given in figure 11. 
A DC blocking capacitor (1000 pF 
typ.) is required on this pin.
OPTIONAL FOR 
OPERATION TO 250 MHz
LO
in
1000 pF
1000 pF
VCC = +5 V
1000 pF
RF
out
1000 pF
Q
ref
Q
mod
I
mod
1 16
215
314
413
512
611
710
89
1000 pF
OPTIONAL FOR 
OPERATION TO 250 MHz
1000 pF
1000 pF
VCC = +5 V
1000 pF
RFout
Q
ref
Q
mod
I
mod
LO
 +
LO
 –
1000 pF
1000 pF
I
ref
1 16
2
15
314
413
512
611
710
89