Preliminary
7-23
RF2713
Rev A2 010129
5
Pin
Function
Description (Modulator Configuration)
Interface Schematic
7Q IF OUT
Same as pin 6, except complementary input.
Same as pin 6.
8Q OUT
Pins 8 and 9 are not used in a normal quadrature modulator applica-
tion, and are left unconnected. Note, however, that the outputs of each
of these pins are independent upconverted I and Q channels. These
signals may be useful in other applications where independent IF chan-
nels are needed. Also note that these outputs are optimized as base-
band outputs for the demodulator configuration. As a result, the gain
rolls-off quickly with increasing frequency. This gain roll-off will limit the
usefulness of these pins as independent I and Q upconverters. If these
outputs are to be used, please refer to the Demodulator pin descrip-
tions regarding load impedances.
9I OUT
Same as pin 8, except Q Mixer’s Output.
Same as pin 8.
10
GND
Ground connection. Keep traces physically short and connect immedi-
ately to ground plane for best performance.
11
GND
Same as pin 10.
12
GND
Same as pin 10.
13
LO INPUT
High impedance, single-ended modulator LO input. The LO applied to
this pin is frequency divided by a factor of 2 and becomes the "Carrier".
For modulation, the Carrier is the center of the modulated output spec-
trum (except in the case of SSB/SC). The input impedance is deter-
mined by an internal 500
Ω bias resistor to V
CC. An external blocking
capacitor should be provided if the pin is connected to a device with DC
present. Matching the input impedance is typically achieved by adding
a51
Ω resistor to ground on the source side of the AC coupling capaci-
tor. For the LO input, maximum power transfer is not critical. The inter-
nal LO switching circuits are controlled by the voltage, not power, into
the part. In cases where the LO source does not have enough available
voltage, a reactive match (voltage transformer) can be used. The LO
circuitry consists of a limiting amplifier followed by a digital divider. The
limiting amp ensures that the flip-flop type divider is driven with a
square wave over a wide range of input levels. Because the flip-flop
uses the rising and falling edges of the limiter output, the quadrature
accuracy of the Carrier supplied to the mixers is directly related to the
duty cycle, or equivalently to the even harmonic content, of the input LO
signal. In particular, care should be taken to ensure that the 2xLO level
input to this pin is at least 20dB below the LO level. Otherwise, the LO
input is not sensitive to the type of input wave form, except for IF fre-
quencies below ~2.5MHz, in which case the LO input should be a
square wave, in order to ensure proper triggering of the flip-flops. IF fre-
quencies below 100kHz are attainable if the LO is a square wave and
sufficiently large DC blocking capacitors are used.
14
VCC
Voltage supply for the entire device. This pin should be well bypassed
at all frequencies (IF, LO, Carrier, Baseband) that are present in the
part.
I/Q OUT
2k
Ω
V
CC
500
Ω
500
Ω
LO IN
V
CC
V
CC
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