RF2713
Pin
1
Function Description (Demodulator Configuration)
Interface Schematic
When the RF2713 is configured as a Quadrature Demodulator, both
mixers are driven by the IF. Whether driving the mixers single-endedly
(as shown in the application schematic) or differentially, the A Inputs
(pins 1 and 3) should be connected to each other. Likewise, both B
Inputs (pins 2 and 4) should be connected to each other. This ensures
that the IF will reach each mixer with the same amplitude and phase,
yielding the best I and Q output amplitude and quadrature balance.
Note that connecting the inputs in parallel changes the input imped-
ance (see the Gilbert Cell mixer equivalent circuit). The single-ended
input impedance (as shown in the application circuit) becomes 630Ω,
but in the balanced configuration, the input impedance would remain
1260Ω.
I INPUT A
VCC
VCC
1260
Ω
1260
Ω
INPUT A
INPUT B
The mixers are Gilbert Cell designs with balanced inputs. The equiva-
lent schematic for one of the mixers is shown on the following page.
The input impedance of each pin is determined by the 1260Ω resistor
to V in parallel with a transistor base. Note from the schematic that
CC
all four input pins have an internally set DC bias. For this reason, all
four inputs (pins 1 through 4) should be DC blocked. The capacitance
values of the blocking capacitors is determined by the IF frequency.
When driving single-endedly, both the series (pins 1 and 3) and shunt
(pins 2 and 4) blocking capacitors should be low impedances, relative
to the 630Ω input impedance.
Same as pin 1, except complementary input.
Same as pin 1, except Q Buffer Amplifier.
Same as pin 3, except complementary input.
See pin 1.
See pin 1.
See pin 1.
2
3
4
5
I INPUT B
Q INPUT A
Q INPUT B
BG OUT
Band Gap voltage reference output. This voltage output is held con-
stant over variations in supply voltage and operating temperature and
may be used as a reference for other external circuitry. This pin should
not be loaded such that the sourced current exceeds 1mA. This pin
should be bypassed with a large (0.1μF) capacitor.
This pin is not used in the Demodulator Configuration, but must be con-
6
I IF OUT
IF OUT
nected to V in order to properly bias the I mixer.
CC
Same as pin 6, except Q mixer.
Same as pin 6.
VCC
7
8
Q IF OUT
Q OUT
Q Mixer’s Baseband Output. This pin is NOT internally DC blocked and
has DC present due to internal biasing. This is an emitter-follower type
output with an internal 2kΩ pull-down resistor. Even though the AC out-
put impedance is ~50Ω, this pin is intended to drive only high imped-
ance loads such as an opamp or an ADC. The output transistor is NOT
biased such that it can drive a large signal into a 50Ω load. DC cou-
pling of this output is permitted provided that the DC impedance to
ground, which appears in parallel with the internal pull-down resistor, is
significantly greater than 2kΩ.
I/Q OUT
2 k
Ω
Same as pin 8, except Q Mixer’s Baseband Output.
Same as pin 8.
9
10
I OUT
GND
Ground connection. Keep traces physically short and connect immedi-
ately to ground plane for best performance.
Same as pin 10.
Same as pin 10.
11
12
GND
GND
7-50
Rev A5 061016
RFMD [ RF MICRO DEVICES ]
