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RF2713
Rev A5 DS061016
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
Pin
Function
Description (Demodulator Configuration)
Interface Schematic
1I INPUT A
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 par-
allel changes the input impedance (see the Gilbert Cell mixer equivalent
circuit). The single-ended input impedance (as shown in the application cir-
cuit) becomes 630
Ω, but in the balanced configuration, the input imped-
ance would remain 1260
Ω.
The mixers are Gilbert Cell designs with balanced inputs. The equivalent
schematic for one of the mixers is shown on the following page. The input
impedance of each pin is determined by the 1260
Ω resistor to VCC in par-
allel with a transistor base. Note from the schematic that 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 630
Ω input impedance.
2I INPUT B
Same as pin 1, except complementary input.
See pin 1.
3Q INPUT A
Same as pin 1, except Q Buffer Amplifier.
See pin 1.
4Q INPUT B
Same as pin 3, except complementary input.
See pin 1.
5BG OUT
Band Gap voltage reference output. This voltage output is held constant
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 (0.1
μF) capacitor.
6I IF OUT
This pin is not used in the Demodulator Configuration, but must be con-
nected to VCC in order to properly bias the I mixer.
7Q IF OUT
Same as pin 6, except Q mixer.
Same as pin 6.
8Q 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 2k
Ω pull-down resistor. Even though the AC output imped-
ance is ~50
Ω, this pin is intended to drive only high impedance loads such
as an opamp or an ADC. The output transistor is NOT biased such that it
can drive a large signal into a 50
Ω load. DC coupling of this output is per-
mitted provided that the DC impedance to ground, which appears in paral-
lel with the internal pull-down resistor, is significantly greater than 2k
Ω.
9I OUT
Same as pin 8, except Q Mixer’s Baseband Output.
Same as pin 8.
10
GND
Ground connection. Keep traces physically short and connect immediately
to ground plane for best performance.
11
GND
Same as pin 10.
12
GND
Same as pin 10.
1260
Ω
1260
Ω
INPUT A
VCC
VCC
INPUT B
IF OUT
I/Q OUT
2 k
Ω
VCC
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