The ADL5380 is a high performance quadrature I-Q
demodulator that covers an RF input frequency range from 400
MHz to 6 GHz. With a NF = 13dB, IP1dB = 12dBm and IIP3 =
31dBm at 2.5GHz, the demodulator offers good dynamic range
suitable for the demanding infrastructure direct-conversion
requirements. The differential RF inputs provide a well-behaved
broad-band input impedance of 50Ω and should be driven from
a 1:1 balun for best performance.
Excellent quadrature accuracy is achieved using on-chip polyphase
filters for LO quadrature generation. Over a wide range of
local oscillator (LO) levels, excellent demodulation accuracy is
achieved with phase and amplitude balances < 0.25 dB and <
0.5o, respectively. The demodulated in-phase (I) and quadrature
(Q) differential outputs are fully buffered. The ADL5380
provides a typical voltage conversion gain of 4dB
Figure 1. Functional Block Diagram
independent of differential load impedances as low as 100 Ω
with a drive capability exceeding 2Vpp in to 200 Ω.
The fully balanced design minimizes effects from 2nd order
distortion. The leakage from the LO port to the RF port is <-
60dBc. Differential DC-offsets at the I and Q outputs are
<10mV. Both of these factors contribute to the excellent IIP2 of
>60dBm.
The ADL5380 operates off a 4.75V to 5.25V supply with a
typical supply current of 200mA. The ADL5380 is fabricated
using Analog Devices’ advanced Silicon-Germanium bipolar
process and is available in a 24-lead exposed paddle LFCSP
package. Performance is specified over a -40oC to +85oC
temperature range.