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Specifications and information are subject to change without notice
WJ Communications, Inc
Phone 1-800-WJ1-4401
FAX: 408-577-6621
e-mail: sales@wj.com
Web site: www.wj.com
Page 2 of 4 April 2005
CV111-3
UMTS-band High Linearity Downconverter
Product Information
The Communications Edge
TM
Device Architecture / Application Circuit Information
Typical Downconverter Performance Chain Analysis
Cumulative Performance
Output
P1dB
(dBm)
13
21.0
11
19.0
2
6.5
21
21.0
21
21.0
Stage
Gain
(dB)
Output
P1dB
(dBm)
Output
IP3
(dBm)
NF
(dB)
Current
(mA)
Gain
(dB)
Output
IP3
(dBm)
41.0
39.0
22.2
38.1
38.1
NF
(dB)
RF Amplifier
RF Filter
LO Amp / MMIC Mixer
IF Amplifier
CV111-1
13
-2
-9
19
21
---
9
23
41
---
23
41
3.2
2.0
9.8
2.1
140
---
100
140
380
3.2
3.3
4.5
5.3
5.3
Cumulative Performance
CV111-3
: The application circuit can be broken up into four main
functions as denoted in the colored dotted areas above: RF/IF
diplexing (purple; this is only used with the cellular-band CV
products), amplifier matching (green), filtering (red), and dc biasing
(blue). There are various placeholders for chip components in the
circuit schematic so that a common PCB can be used for all WJ
single-branch converters. Additional placeholders for other optional
functions such as filtering are also included.
RF / IF Amplifier Matching:
The RF amplifier requires a
matching element (C12) for optimal gain and input return loss
performance. The IF amplifier requires matching elements to
optimize the performance of the amplifier to the desired IF center
frequency. Since IF bandwidths are typically on the order of 5 to
10%, a simple two element matching network, in the form of either
a high-pass or low-pass filter structure, is sufficient to match the
MMIC IF amplifier over these narrow bandwidths. Proper
component values for other IF center frequencies can be provided by
emailing to applications.engineering@wj.com.
RF Bandpass Filtering:
Bandpass filtering is recommended to
achieve the best noise figure performance with the downconverter.
The bandpass filter, implemented with a SAW filter on the
application circuit, allows for the suppression of noise from the
image frequency. It is permissible to not use a filter and use a 2 dB
pad with R6, R7, and R16 instead with slightly degraded noise
figure performance.
External Diplexer:
This is only used with the cellular-band CV
products. The mixer performs the diplexing internally for the
CV111-3; therefore the components shown in the diplexer section
should be loaded as follows: C2 = C14 = 0
Ω
.
IF and LO Lowpass Filtering (optional):
Filtering of unwanted
RF and LO signals are typically performed in the IF chain. This
filtering function may be realized using lumped elements;
placeholders (L9, C21, C22) are provided in the application circuit
to allow for lumped-element filtering to be implemented if desired.
The LO lowpass filter is used only in the cellular-band CV products;
it should not be used for this product. L1 should be loaded with a 0
Ω
jumper.
DC biasing:
DC bias must be provided for the RF, LO and IF
amplifiers in the converter. R1 sets the operating current for the last
stage of the LO amplifier and is chosen to optimize the mixer LO
drive level. Proper RF chokes and bypass capacitors are chosen for
proper amplifier biasing at the intended frequency of operation. The
“+5 V” dc bias should be supplied directly from a voltage regulator.
RF Amp Bias
IF Amp Bias
LO Amp Bias
LO Amp Bias
RF Bandpass Filter /
Attenuator Pad
LO Lowpass Filter
(not used in this product)
Optional IF
Lowpass Filter
RF Amp Matching
IF Amp Matching
RF / IF Diplexer
(used for cellular versions only)
Printed Circuit Board Material:
.014” FR-4, 4 layers, .062” total thickness
G
28
R
27
G
26
M
25
G
24
I
23
G
22
1
2
3
4
5
6
7
21
20
19
18
17
16
15
8
G
9
10
G
11
M
12
G
13
L
14
G
IF Amp
RF Amp
LO Driver Amp
IF OUT
GND
N/C
GND
BIAS
GND
LO IN
RF OUT
GND
N/C
GND
N/C
GND
MIXRF
N
RF
IF
LO