ltc5590 Linear Technology Corporation, ltc5590 Datasheet - Page 17

• Manufacturer Part Number: ltc5590
• Description: Dual 600mhz To 1.7ghz High Dynamic Range Downconverting Mixer
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
Table 4. Performance Comparison with V
(RF = 900MHz, High Side LO, IF = 190MHz)
The IFBA pin (Pin 20) is available for reducing the DC
current consumption of the IF amplifier, at the expense of
IIP3. The nominal DC voltage at Pin 20 is 2.1V, and this pin
should be left open-circuited for optimum performance.
The internal bias circuit produces a 4mA reference for
the IF amplifier, which causes the amplifier to draw ap-
proximately 96mA. If resistor R1A is connected to Pin 20
as shown in Figure 7, a portion of the reference current
can be shunted to ground, resulting in reduced IF ampli-
fier current. For example, R1A = 1k will shunt away 1mA
from Pin 20 and the IF amplifier current will be reduced
by 28% to approximately 69mA. Table 5 summarizes RF
performance versus IF amplifier current.
Table 5. Mixer Performance with Reduced IF Amplifier Current
RF = 900MHz, High Side LO, IF = 190MHz, V
RF = 1400MHz, Low Side LO, IF = 190MHz, V
Low Power Mode
Both mixer channels can be set to low power mode us-
ing the I
current mode of operation when lower RF performance is
acceptable, reducing power consumption by 37%. Figure
12 shows a simplified schematic of the I
V
4.7kΩ
2.2kΩ
4.7kΩ
2.2kΩ
(V)
3.3
Open
Open
CCIF
1kΩ
1kΩ
5
R1
R1
SEL
Open
Open
R2A
(Ω)
1k
pin. This allows flexibility to select a reduced
(mA)
(mA)
I
I
191
173
156
137
191
173
156
137
CCIF
CCIF
(mA)
I
191
191
200
CCIF
(dB)
(dB)
8.7
8.7
8.6
8.5
8.4
8.5
8.5
8.4
G
G
C
C
(dB)
8.7
7.5
8.7
G
C
(dBm)
(dBm)
26.0
25.6
25.0
24.1
27.3
26.8
26.2
25.1
IIP3
IIP3
CC
(dBm)
P1dB
CC
10.7
11.4
14.1
CCIF
= V
= V
CCIF
CCIF
= 3.3V and 5V
SEL
(dBm)
P1dB
P1dB
(dB)
10.7
10.6
10.6
10.5
10.9
10.9
10.8
= 3.3V
(dBm)
11
= 3.3V
26.0
26.0
25.5
IIP3
pin interface.
(dB)
(dB)
(dB)
9.75
9.7
9.7
9.6
9.6
9.7
9.6
9.6
9.6
9.7
9.8
NF
NF
NF
Table 6. Performance Comparison Between Different Power Modes
RF = 900MHz, High Side LO, IF = 190MHz, V
Enable Interface
Figure 13 shows a simplified schematic of the ENA pin
interface (ENB is identical). To enable channel A, the ENA
voltage must be greater than 2.5V. If the enable function
is not required, the enable pin can be connected directly
to V
the power supply voltage (V
When I
nominal DC current. When I
current in both channels is reduced, thus reducing power
consumption. The performance in low power mode and
normal power mode are compared in Table 6.
High
Low
I
SEL
CC
. The voltage at the enable pin should never exceed
SEL
19
17
19
18
is set low (<0.3V), both channels operate at
Figure 12. I
I
(mA)
V
TOTAL
ENA
V
I
379
239
SEL
CCA
CCA
Figure 13. ENA Interface Schematic
SEL
(dB)
500Ω
8.7
7.7
500Ω
G
C
Interface Schematic
LTC5590
SEL
LTC5590
CC
) by more than 0.3V. If this
(dBm)
is set high (>2.5V), the DC
26.0
21.5
IIP3
CC
= V
BIAS A
BIAS B
V
CCIF
CCB
LTC5590
5590 F13
(dBm)
P1dB
10.7
10.4
= 3.3V
CLAMP
ESD
5590 F13
17
(dB)
9.7
9.9
NF
5590f