SL6440 Ver la hoja de datos (PDF) - Zarlink Semiconductor Inc
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SL6440 Datasheet PDF : 5 Pages
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SL6440
CIRCUIT DESCRIPTION
The SL6440 is a high level mixer designed to have a linear
RF performance. The linearity can be programmed using the
IP pin (11).
The output pins are open collector outputs so that the
conversion gain and output loads can be chosen for the
specific application.
Since the outputs are open collectors they should be
returned to a supply VCC1 through a load.
The choice of VCC1 is important since it must be ensured that
the voltage on pins 3 and 14 is not low enough to saturate the
output transistors and so limit the signal swing unnecessarily.
If the voltage on pins 3 and 14 is always greater than VCC2 the
outputs will not saturate. The output frequency response will
reduce as the output transistors near saturation.
Minimum VCC1
= (IP x RL) + VS + VCC2
where IP
= programmed current
RL
= DC load resistance
VS
= max signal swing at output
if the signal swing is not known:
minimum VCC1 = 2 (IP x RL) + VCC2
In this case the signal will be limiting at the input before the
output saturates.
The device has a separates supply (VCC2) for the oscillator
buffer (pin 4).
The current (IP) programmed into pin 11 can be supplied via
a resistor from VCC1 or form a current source.
The conversion gain is equal to
GdB = 20 Log
RL IP
for single-ended output
56.61 IP + 0.0785
GdB = 20 Log
2RL IP
for differential output
56.61 IP + 0.0785
Device dissipation is calculated using the formula
mW diss
= 2 IP VO + VPIP + VCC2 Diss
where VO
= voltage on pin 3 or pin 14
VP
= voltage on pin 11
IP
= programming current (mA)
VCC2 Diss = dissipation obtained from graph (Fig.6)
As an example Fig.7 shows typical dissipations assuming
VCC1 and VO are equal. This may not be the case in pratice and
the device dissipation will have to be calculated for any
particular application.
Fig.5 shows the intermodulation performance against IP.
The curves are independent of VCC1 and VCC2 but if VCC1
becomes too low the output signal swing cannot be
accommodated, and if VCC2 becomes too low the circuit will
not provide enough drive to sink the programmed current.
Examples are shown of performance at various supply
voltages.
The current in pin 14 is equal to the current in pin 3 which is
equal to the current in pin 11.
50
50
VCC1
0.1µ
10µ
500
OUTPUT
VCC2
4
10µ
0.1µ
LO
INPUT
5
0.001µ
50
3
14
11
0.1µ
SL6440
0.001µ
13
50
6
12
0.001µ
RF
INPUT
Fig.2 Typical application and test circuit
-1dBm COMPRESSION POINT
VCC1 = 15V
VCC2 = 12V
VCC1 = 12V
VCC2 = 10V
LOCAL OSCILLATOR = 30MHz 0dBm
RF INPUT = 40MHz
-10
IF = 10MHz
0
+10
++
+
10
20
30
40
50
60
70
(mA)
TOTAL OUTPUT CURRENT (2IP)
Fig.3 Compression point v. total output current
0
-1
-2
-3
-4
-5
-6
RF INPUT 0dBm
LOCAL OSCILLATOR INPUT LEVEL
-7
VCC1 = 6V
VCC2 = 5V
+
-8
IP = 24mA
-9
VCC1 = 12V
VCC2 = 10V
++
-10
-11
-12
SIGNAL 10MHz HIGHER
THAN LOCAL OSCILLATOR
+
+
10
100
LOCAL OSCILLATOR FREQUENCY MHz
1000
Fig.4 Frequency response at constant output IF
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