MAX2022ETX+TD Maxim Integrated, MAX2022ETX+TD Datasheet - Page 16

• Manufacturer Part Number: MAX2022ETX+TD
• Description: Modulator / Demodulator 1.5-2.5GHz Quadratr Modulator
• Manufacturer: Maxim Integrated

Specifications of MAX2022ETX+TD

• Rohs: yes

Figure 4. MAX2022 Demodulator Configuration
Figure 5. Demodulator Combining Diagram
MAX2022
RF Demodulator
The MAX2022 can also be used as an RF demodulator
(see
to baseband. The single-ended RF input accepts signals
from 1500MHz to 3000MHz. The passive mixer architec-
ture produces a conversion loss of typically 9.2dB and a
noise figure of 9.4dB. The downconverter is optimized
for high linearity of typically +39dBm IIP3. A wide I/Q port
bandwidth allows the port to be used as an image-reject
mixer for downconversion to a quadrature IF frequency.
The RF and LO inputs are internally matched to 50Ω.
Thus, no matching components are required, and only
DC-blocking capacitors are needed for interfacing.
Demodulator Output Port Considerations
Much like in the modulator case, the four baseband ports
require some form of DC return to establish a common
mode that the on-chip circuitry drives. This is achieved
by directly DC-coupling to the baseband ports (staying
www.maximintegrated.com
Figure
4), downconverting an RF input signal directly
RF
Q+
Q-
I+
I-
3dB PAD
3dB PAD
3dB PAD
3dB PAD
DC RETURN FOR THE ON-CHIP CIRCUITRY.
3dB PADS LOOK LIKE 160Ω TO GROUND
AND PROVIDES THE COMMON-MODE
MAX2022
DC BLOCK
DC BLOCK
DC BLOCK
DC BLOCK
90
0
0°
180°
0°
180°
MINI-CIRCUITS
MINI-CIRCUITS
DC RETURN
DC RETURN
DIPLEXER/
DIPLEXER/
ZFSCJ-2-1
ZFSCJ-2-1
LO
Downconversion 1500MHz to 3000MHz
within the -2.5V to +1.5V common-mode range), through
an inductor to ground, or through a low-value resistor to
ground.
used to connect to each baseband port for demodulator
operation. This network provides a common-mode DC
return, implements a high-frequency diplexer to terminate
unwanted RF terms, and also provides an impedance
transformation to a possible higher impedance baseband
amplifier.
The network C
network to terminate the high frequencies into a load
while passing the desired lower IF frequencies. Elements
L
transformer. Depending on the impedance being trans-
formed and the desired bandwidth, a fewer number of ele-
ments can be used. It is suggested that L
be used since they are part of the high-frequency diplexer.
If power matching is not a concern, then this reduces the
elements to just the diplexer.
a
, C
MATCHING
MATCHING
Quadrature Modulator/Demodulator
b
90°
, L
Figure 6
High-Dynamic-Range, Direct Up/
b
, C
c
, L
MINI-CIRCUITS
a
ZFSC-2-1W-S+
0° COMBINER
, R
c
shows a typical network that would be
, and C
a
, L
a
, and C
d
provide a possible impedance
ADC
ADC
b
form a highpass/lowpass
Maxim Integrated │ 16
a
and C
b
always