LT5521
Very High Linearity
Active Mixer
FEATURES
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DESCRIPTIO
Wideband Output Frequency Range to 3.7GHz
+24.2dBm IIP3 at 1.95GHz RF Output
Low LO Leakage: –42dBm
Integrated LO Buffer: Low LO Drive Level
Single-Ended LO Drive
Wide Single Supply Range: 3.15V to 5.25V
Double-Balanced Active Mixer
Shutdown Function
16-Lead (4mm
×
4mm) QFN Package
The LT
®
5521 is a very high linearity mixer optimized for
low distortion and low LO leakage applications. The chip
includes a high speed LO buffer with single-ended input
and a double-balanced active mixer. The LT5521 requires
only –5dBm LO input power to achieve excellent distor-
tion and noise performance, while reducing external drive
circuit requirements. The LO buffer is internally 50Ω
matched for wideband operation.
With a 250MHz input, a 1.7GHz LO and a 1.95GHz output
frequency, the mixer has a typical IIP3 of +24.2dBm,
–0.5dB conversion gain and a 12.5dB noise figure.
The LT5521 offers exceptional LO-RF isolation, greatly
reducing the need for output filtering to meet LO suppres-
sion requirements.
The device is designed to work over a supply voltage range
from 3.15V to 5.25V.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Cellular, W-CDMA, PHS and UMTS Infrastructure
Cable Downlink Infrastructure
Wireless Infrastructure
Fixed Wireless Access Equipment
High Linearity Mixer Applications
TYPICAL APPLICATIO
LO INPUT
–5dBm
6.8pF
LO
110Ω
IN
+
1:1
10pF
6.8pF
IN
–
GND
IF
INPUT
OUT
+
OUT
–
2.7nH
OUTPUT POWER (dBm)
BPF
1nF
4:1
82pF
BPF
2.7nH
PA
82pF
RF
OUTPUT
1nF
110Ω
BIAS
EN V
CC
V
CC
V
CC
1nF
5V DC
1µF
5521 TA01
U
Fundamental, 3rd Order
Intermodulation Distortion
vs Input Power
20
0
P
FUND
–20
–40
IM3
–60
–80
–100
–14 –12 –10 –8 –6 –4 –2
P
IN
(dBm)
f
IF
= 250MHz
f
LO
= 1.7GHz
f
RF
= 1.95GHz
P
LO
= –5dBm
T
A
= 25°C
0
2
4
6
5521 TA02
U
U
5521f
1
LT5521
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
Power Supply Voltage ........................................... 5.5V
Enable Voltage ............................... –0.2V to V
CC
+ 0.2V
LO Input Power ................................................ +10dBm
LO Input DC Voltage ..................................... 0V to 1.5V
IF Input Power ................................................. +10dBm
Difference Voltage Across Output Pins ................
±1.5V
Maximum Pin 2 or Pin 3 Current ......................... 34mA
Operating Ambient Temperature Range .. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 125°C
Maximum Junction Temperature .......................... 125°C
GND
GND
16 15 14 13
GND 1
IN
+
2
IN
–
3
17
12 OUT
+
11 GND
10 GND
9
5
6
7
8
OUT
–
GND
LO
ORDER PART
NUMBER
LT5521EUF
GND 4
V
CC
V
CC
UF PACKAGE
16-LEAD (4mm
×
4mm) PLASTIC QFN
V
CC
UF PART
MARKING
5521
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN 17) IS GND
MUST BE SOLDERED TO PCB
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DC ELECTRICAL CHARACTERISTICS
V
CC
= 5V, EN = 2.9V, T
A
= 25°C unless otherwise noted.
Test circuit shown in Figure 1. (Note 2)
PARAMETER
Supply Voltage
Supply Current
Shutdown Current
Enable (EN) Low = Off, High = On
Enable Mode
Disable Mode
Enable Current
Shutdown Enable Current
Turn-On Time (Note 3)
Turn-Off Time (Note 4)
LO Voltage (Pin 15)
Input Voltage (Pins 2, 3)
Internally Biased
V
CC
= 5V, Internally Biased
V
CC
= 3.3V, Internally Biased
EN = High
EN = Low
EN = 5V
EN = 0.2V
137
0.1
200
200
0.96
2.20
0.46
2.9
0.2
V
V
µA
µA
ns
ns
V
V
V
EN = 0.2V
CONDITIONS
MIN
3.15
82
20
TYP
MAX
5.25
98
100
UNITS
V
mA
µA
AC ELECTRICAL CHARACTERISTICS
Test circuit shown in Figure 1. (Note 2)
PARAMETER
LO Frequency Range
Input Frequency Range
Output Frequency Range
LO Input Power
LO Return Loss
Output Return Loss
Input Return Loss (Pins 2, 3)
V
CC
= 5V, EN = 2.9V, T
A
= 25°C unless otherwise noted.
MIN
TYP
10 to 4000
10 to 3000
10 to 3700
–5
1
MAX
UNITS
MHz
MHz
MHz
dBm
dB
dB
dB
5521f
CONDITIONS
Z
O
= 50Ω, f
LO
= 1700MHz
Requires Matching
Requires Matching
EN
12
12
15
2
U
W
U
U
W W
W
LT5521
AC ELECTRICAL CHARACTERISTICS
PARAMETER
Conversion Gain
Conversion Gain Variation vs Temperature
Input P1dB
Single-Side Band Noise Figure
IIP3
IIP2 (Note 6)
LO-RF Leakage
LO-IF Leakage
V
CC
= 5V, EN = 2.9V, f
IF
= 250MHz, P
IF
= –7dBm, f
LO
= 1700MHz,
P
LO
= –5dBm, f
RF
= 1950MHz, T
A
= 25°C. Test circuit shown in Figure 1.
CONDITIONS
MIN
TYP
–0.5
–0.009
+10
12.5
Two Tones,
∆f
IF
= 5MHz, P
IF
= –7dBm/Tone
Two Tones,
∆f
IF
= 5MHz, P
IF
= –7dBm/Tone,
f
LO
+ f
IF1
+ f
IF2
+24.2
+49
–42
–40
MAX
UNITS
dB
dB/°C
dBm
dB
dBm
dBm
dBm
dBm
V
CC
= 5V, EN = 2.9V, f
IF
= 44MHz, P
IF
= –7dBm, f
LO
= 1001MHz, P
LO
= –5dBm, f
RF
= 1045MHz, T
A
= 25°C.
PARAMETER
Conversion Gain
Conversion Gain Variation vs Temperature
Input P1dB
Single-Side Band Noise Figure
IIP3
IIP2 (Note 6)
LO-RF Leakage
LO-IF Leakage
Two Tones,
∆f
IF
= 5MHz, P
IF
= –7dBm/Tone
Two Tones,
∆f
IF
= 5MHz, P
IF
= –7dBm/Tone,
f
LO
+ f
IF1
+ f
IF2
CONDITIONS
MIN
TYP
–0.5
–0.012
+10
12.8
+24.5
+49
–38
–59
MAX
UNITS
dB
dB/°C
dBm
dB
dBm
dBm
dBm
dBm
V
CC
= 3.3V, EN = 2.9V, f
IF
= 250MHz, P
IF
= –7dBm, f
LO
= 1700MHz, P
LO
= –5dBm, f
RF
= 1950MHz, T
A
= 25°C. (Note 5)
PARAMETER
Conversion Gain
Conversion Gain Variation vs Temperature
Input P1dB
Single-Side Band Noise Figure
IIP3
IIP2 (Note 6)
LO-RF Leakage
LO-IF Leakage
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Specifications over the –40°C to 85°C temperature range are
assured by design, characterization and correlation with statistical process
controls.
Note 3:
Interval from the rising edge of the Enable input to the time when
the RF output is within 1dB of its steady-state output.
Two Tones,
∆f
IF
= 5MHz, P
IF
= –7dBm/Tone
Two Tones,
∆f
IF
= 5MHz, P
IF
= –7dBm/Tone,
f
LO
+ f
IF1
+ f
IF2
CONDITIONS
MIN
TYP
–0.5
–0.013
+11
13.5
+25.8
+50
–36
–60
MAX
UNITS
dB
dB/°C
dBm
dB
dBm
dBm
dBm
dBm
Note 4:
Interval from the falling edge of the Enable signal to a 20dB drop
in the RF output power.
Note 5:
R1 = R7 = 22.6Ω, Z1 = Z7 = 100nH.
Note 6:
Second harmonic distortion measured at f
LO
+ f
IF1
+ f
IF2
.
5521f
3
LT5521
TYPICAL DC PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
(5V Application)
100
95
90
85
85°C
I
CC
(mA)
25°C
80
75
–40°C
70
65
60
4.7
4.8
4.9
5.1
5.0
V
CC
(V)
5.2
5.3
5521 G01
I
CC
(mA)
TYPICAL AC PERFOR A CE CHARACTERISTICS
f
LO
= 1700MHz, f
IF
= 250MHz, f
RF
= 1950MHz, P
LO
= –5dBm, V
CC
= 5V, EN = 2.9V, T
A
= 25°C, unless otherwise noted. Test circuit
shown in Figure 1 is tuned for 1.95GHz output frequency and V
CC
= 5V.
Fundamental, 2nd and 3rd Order
Intermodulation Distortion
vs Input Power
20
0
OUTPUT POWER (dBm)
85°C
25°C
–40°C
P
FUND
–20
–40
IM3
G
C
(dB)
–0.5
–1.0
–1.5
–2.0
–2.5
0
–25 –20 –15 –10 –5
P
IN
(dBm)
85°C
G
C
(dB)
IM2
–60
IM2
–80
IM3
–100
–14 –12 –10 –8 –6 –4 –2
P
IN
(dBm)
0
2
4
5521 G03
4
U W
6
Test circuit shown in Figure 1.
Supply Current vs Supply Voltage
(3.3V Application)
110
100
85°C
90
25°C
80
–40°C
70
60
50
3.1
3.2
3.3
V
CC
(V)
3.4
3.5
5521 G02
U W
Conversion Gain vs Input Power
1.0
0.5
0
–40°C
Conversion Gain and IIP3
vs RF Frequency
10
8
6
IIP3
25
24
23
IIP3 (dBm)
25°C
4
2
0
–2
–4
1750
85°C
25°C
–40°C
22
21
G
C
20
19
18
2150
5521 G05
5
10
15
1850
1950
RF
OUT
(MHz)
2050
5521 G04
5521f
LT5521
TYPICAL AC PERFOR A CE CHARACTERISTICS
LO-RF Leakage vs LO Frequency
–36
–38
–40°C
LEAKAGE (dBm)
f
LO
= 1700MHz, f
IF
= 250MHz, f
RF
= 1950MHz,
P
LO
= –5dBm, V
CC
= 5V, EN = 2.9V, T
A
= 25°C, unless otherwise noted. Test circuit shown in Figure 1 is tuned for 1.95GHz output
frequency and V
CC
= 5V.
Conversion Gain, IIP3 and Noise
Figure vs Supply Voltage
10
8
6
G
C
(dB)
–40
–42
–44
–46
–48
1500 1550 1600 1650 1700 1750 1800 1850 1900
LO FREQUENCY (MHz)
5521 G06
85°C
G
C
(dB)
25°C
LO-RF Leakage vs LO Power
–32
–34
–36
–34
–36
–38
LO LEAKAGE (dBm)
LO LEAKAGE (dBm)
–38
–40°C
–40
–42
–44
–46
–48
–50
–25
–20
–15 –10 –5
0
LO POWER (dBm)
5
10
25°C
85°C
–40
–42
–44
–40°C
85°C
25°C
NOISE FIGURE (dB)
5521 G09
Low Side LO (LS) and High Side
LO (HS) Comparison: Conversion
Gain and IIP3 vs RF Frequency
10
LS
8
6
G
C
(dB)
LS: R1 = R7 = 110Ω
4 HS: R1 = R7 = 121Ω
f
IF
= 250MHz
2
0
–2
–4
1750
G
C
LS
HS
HS
IIP3
26
24
13.5
NOISE FIGURE (dB)
1850
1950
RF
OUT
(MHz)
U W
Conversion Gain and IIP3
vs LO Power
30
10
IIP3 (dBm) AND NOISE FIGURE (dB)
25
24
IIP3
23
IIP3 (dBm)
IIP3
25
85°C
25°C
–40°C
20
15
10
8
6
4
2
0
–2
–4
–25 –20
4
2
NF
85°C
25°C
–40°C
22
21
G
C
20
19
18
10
G
C
0
–2
4.6
5
0
5.4
4.7
4.8
4.9
5.0 5.1
V
CC
(V)
5.2
5.3
0
–15 –10 –5
LO POWER (dBm)
5
5521 G07
5521 G08
LO-RF Leakage vs Supply Voltage
20
19
18
17
16
15
14
13
12
11
4.8
4.9
5.1
5.0
V
CC
(V)
5.2
5.3
5521 G10
Noise Figure vs LO Power
85°C
25°C
–46
–48
–50
4.7
–40°C
10
–20
–15
–5
–10
LO POWER (dBm)
0
5
5521 G11
Low Side LO (LS) and High Side
LO (HS) Comparison: Noise Figure
vs RF Frequency
LS: R1 = R7 = 110Ω
13.3 HS: R1 = R7 = 121Ω
f = 250MHz
13.1
IF
22
IIP3 (dBm)
20
18
16
14
12
2150
5521 G13
12.9
12.7
12.5
12.3
12.1
11.9
11.7
11.5
1700 1750 1800 1850 1900 1950 2000 2050 2100
RF
OUT
(MHz)
5521 G14
HS
LS
2050
5521f
5
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