LA7790M [SANYO]
QPSK Transmitter for Cable TV; QPSK发射的卫星电视
| 型号： | LA7790M |
| 厂家： | 
SANYO SEMICON DEVICE |
| 描述： | QPSK Transmitter for Cable TV |
| 文件： | 总14页 (文件大小：175K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Ordering number : EN5689A
Monolithic Linear IC
LA7790M
QPSK Transmitter for Cable TV
• Varactor diode-based VCO
• Muting
• Electronic volume control
• Power-saving modes
• Switchable output frequency range
• Power supply voltage of 5 V (4.5 to 5.5 V)
Overview
The LA7790M is a QPSK data transmitter for digital cable
TV applications. By integrating the I/Q quadrature
modulator, RF amplifier, electronic volume control, mute
control, and other functions onto a single chip, parts count
is reduced and set size is miniaturized.
Features
Package Dimensions
unit: mm
• Maximum RF amplifier output level of +10 dBm (75Ω
terminator), suitable for directly driving the cable.
• RF output frequency range of 5 to 70 MHz. Frequency
range selection function permits broadband designs.
• Electronic volume control for direct-current control of
RF output level.
3108-MFP24D
[LA7790M]
• Muting ensures ample attenuation during periods with
no transmission.
• Support for both internal and external bias for I/Q
modulation inputs.
• Support for I/Q modulation frequencies up to 10 MHz.
(typ: 500 mVp-p)
Functions
• I/Q quadrature modulator
• I/Q input bias power supply
• RF amplifier
SANYO: MFP24D
Ambient temperature, Ta (°C)
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
5061998RM (OT) No. 5689-1/14
LA7790M
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Maximum power supply voltage
Circuit voltage
Symbol
Conditions
Ratings
Unit
V
V
CC max
Vmax
I11
Pins 1, 10, and 24
7
Pins 1, 12, 17, 20, 21, and 23
Output lead-in current
Ta ≤ 54°C
VCC
V
1
2
mA
mA
mW
°C
Circuit current
I19
Allowable power dissipation
Operating ambient temperature
Storage temperature
Pd max
Topr
650
–20 to +70
–55 to +150
Tstg
°C
Recommended Conditions at Ta = 25°C
Parameter
Symbol
CC op
Conditions
Ratings
Unit
V
Operating power supply voltage
V
Pins 1, 10, and 24
4.5 to 5.5
Operating Characteristics at Ta = 25°C, V = 5.0 V
CC
Ratings
typ
Parameter
Symbol
Conditions
Unit
min
max
Current drain
Circuit current 1
Circuit current 2
I1
With no signal, pin 1
26
33
44
mA
mA
I
24 + I10 With no signal, pins 24 and 10
44
55
73
Modulator fo: f(V19) = 25 MHz
Output frequency range
f(V19)
5
70
–2
MHz
dBm
Note 1: V20 = V23 = GND,
Output signal level
V19(DSB)
–7
–4
V12 = V17 = V21 = VCC, S1 = A
V19(HD2) Note 2: V20 = V23 = GND,
40
35
dB
dB
Output harmonic distortion
V19(HD3) V12 = V17 = V21 = VCC, S1 = A
Note 3: V20 = V23 = GND,
V19(2fo)
Output secondary harmonic distortion
Output tertiary harmonic distortion
Carrier suppression ratio
20
8
dB
dB
dB
dB
V
12 = V17 = V21 = VCC, S1 = A
Note 3: V20 = V23 = GND,
12 = V17 = V21 = VCC, S1 = A
Note 4: V20 = V23 = GND,
12 = V17 = V21 = VCC, S1 = A
Note 5: V20 = V23 = GND,
12 = V17 = V21 = VCC, S1 = A
V19(3fo)
V19(fo)
V
30
30
V
Sideband suppression ratio
V19(SSB)
V
I input level
V4.5
V8.9
V4, 5
V8, 9
V6
V4.5 = |V4 — V5|
500
500
2.1
2.1
2.1
mVp-p
Q input level
V8.9 = |V8 — V9|
mVp-p
I input DC voltage
Q input DC voltage
Reference voltage
Variable attenuator
Minimum gain control voltage
External DC bias voltage
External DC bias voltage
Internal DC bias voltage
1.9
1.9
1.9
2.3
2.3
2.3
V
V
V
V21
V12 = V17 = VCC, V20 = V23 = GND, S1 = A
0
0.5
V
Note 6: V20 = V23 = GND, V12 = V17 = VCC
S1 = A, V21 = VCC → 0.5 V
,
Gain range
V19(GR)
45
dB
V12 = V17 = V21 = VCC
,
Modulator output impedance
VCO
R19
80
120
160
Ω
V20 = V23 = GND, S1 = A
V12 = V17 = V21 = VCC
,
20
500
200
280
900
400
MHz
mVp-p
Ω
Oscillator frequency range
VCO output level
f(osc)
V11(fo)
R11
V
20 = V23 = GND, S1 = A
V12 = V17 = V21 = VCC
,
700
300
V20 = V23 = GND, S1 = A
V12 = V17 = V21 = VCC
,
VCO output impedance
Band switch
V20 = V23 = GND, S1 = A
Band switch 1 “H” level
f(V19) = 25 MHz
Note 7: V12 = V21 = VCC,
V17H
V17L
4
V
V
V
20 = V23 = GND, S1 = A
Band switch 1 “L” level
f(V19) = 12.5 MHz
Note 7: V12 = V21 = VCC,
1
V
20 = V23 = GND, S1 = A
Continued on next page.
No. 5689-2/14
LA7790M
Continued from preceding page.
Ratings
typ
Parameter
Symbol
Conditions
Unit
min
max
Band switch 2 “H” level
f(V11) = 25 MHz
Note 7: V17 = V21 = VCC
V20 = V23 = GND, S1 = A
Note 7: V17 = V21 = VCC
,
V12H
V12L
4
7
V
V
Band switch 2 “L” level
f(V11) = 12.5 MHz
,
1
V20 = V23 = GND, S1 = A
RF output amplifier
Note 8: V12 = V17 = V21 = VCC
,
Maximum output level
V1 max
10
13
dBm
V20 = V23 = GND, SG3 = –6 dBm, S1 = A
V1(HD2)
V1(HD3)
40
40
dBc
dBc
Note 8: V12 = V17 = V21 = VCC
,
Maximum output distortion
V
20 = V23 = GND, SG3 = –6 dBm, S1 = A
Muting
V12 = V17 = V21 = VCC
20 = GND, S1 = B
V12 = V17 = V21 = VCC
20 = GND, S1 = B
Note 9: V23 = 1 V → 4 V
12 = V17 = V21 = VCC, V20 = GND, S1 = B
,
Muting on voltage
V23H
V23L
4
V
V
V
,
Muting off voltage
Muting attenuation
1
V
V1(mute)
70
dB
V
Power save function
Power save on voltage
Power save off voltage
Power save current
V20H
V20L
I1
4
0
V
V
1
Note 10: V20 = 4 V
0.1
mA
Pin Assignment
No. 5689-3/14
LA7790M
Note 1
Note 2
Input: SG1 =1 MHz CW, 500 mVp-p, SG2 = No Signal or
SG2 = 1 MHz CW, 500 mVp-p, SG1 = No Signal
Output:
Input: Same as Note 1
Output:
Note 3
Input: Same as Note 1
Output:
Note 4
Note 5
Input: SG1 = SG2 = 1 MHz CW, 500 mVp-p
Output:
Input: SG1 = 1 MHz CW, 500 mVp-p, 0deg
SG1 = 1 MHz CW, 500 mVp-p, 90deg
Output:
Note 6
Input: SG1 = 1 MHz CW, 500 mVp-p
Output:
No. 5689-4/14
LA7790M
Note 7
Input: SG1 = 1 MHz CW, 500 mVp-p
Output:
Note 8
Input: SG3 = 25 MHz CW, –6 dBm
Output:
Note 9
Input: SG1 = 1 MHz CW, 500 mVp-p
Output:
Note 10
I = pin 1 current when V20 = 4 V (power save on).
1
No. 5689-5/14
LA7790M
Measurement Circuit
No. 5689-6/14
LA7790M
Sample Application Circuit
No. 5689-7/14
LA7790M
1. Modulator
The modulator consists of two identical multiplier circuits, creating I and Q channels. Pins 4 & 5 and pins 8 & 9 are I
and Q channel inputs, respectively. These pins must be biased at 2.1 ± 0.2 V. Pin 6 is an internal 2.1 V bias. This
internal bias can be used if the I & Q data inputs are AC coupled, but an external bias must be used in the case of DC
coupled data inputs. Carrier suppression is improved if the offset voltages between pins 4 & 5 and pins 8 & 9 are
small.
(1) AC coupled application
4
+
I input
5
2.1 V
6
8
Q input
+
9
(2) DC coupled application
+
4
I input
+
2.1 V
5
6
+
8
Q input
+
2.1 V
9
No. 5689-8/14
LA7790M
Equivalent circuit of modulator block
VCC
300
300
to HPF
from
Divider
from
Divider
bias
2.1 V
1 k
300
400
400
300
300
300
1.4 mA
1.4 mA
1.4 mA
1.4 mA
4
5
6
8
9
I-INPUT
Q-INPUT
Unit (resistance : Ω)
No. 5689-9/14
LA7790M
2. Attenuator
The attenuator input signal comes from the modulator output via a high pass filter (f = 2 MHz). The modulator
C
output is pin 19. Pin 19 is connected to the emitter of an NPN emitter follower through a 100 Ω resistor. The emitter
sink current is about 1 mA, but can be increased by the addition of an external resistor between pin 19 and ground.
The minimum value for the external resistor is 1.5 kΩ.
The output level of pin 19 can be adjusted using pin 21. Pin 21 is connected to the base of a PNP emitter follower
through a 300 Ω resistor. When pin 21 = 0 V, the base current is about 10 µA.
Equivalent circuit of attenuator block
VCC
1 k
1 k
Control
Circuit
300
Gain
control
0 to 10 µA
100
MOD
ATT
21
1 k
19
output
HPF
1 mA
1 mA
1 mA
From Modulator
Unit (resistance : Ω)
3. RF Amplifier
The RF amplifier input signal comes from the attenuator output after the harmonics are removed by the LPF. The RF
amplifier is composed of a two-stage amplifier and includes mute and power save functions.
The gain of the RF amplifier can be adjusted using the external input resistor connected to pin 22 and the external
load resistor connected to pin 1. The input of pin 22 must be AC coupled. The output of pin 1 must be connected to
V
CC
via a choke coil. Pin 23 (mute control) and pin 20 (power save control) are both high impedance inputs (base
current less than 10 µA). For normal operation, the voltage at pins 20 and 23 must be less than 1 V. For Mute and
Power Save operation, the voltage at pins 20 are 23 must be between V –1 and V
.
CC
CC
No. 5689-10/14
LA7790M
Equivalent circuit of RF amplifier block
VCC
Choke
Coil
Vout
Load resistor
75
0 to 3µA
RF
output
Mute
23
1
30 mA
VCC
VCC
300
RF input
R1
22
5 k
R2
300
from
1st stage
Vin
Mute
2nd stage
1st stage
Power
save
0 to 4 µA
300
20
3.5 V
Power save
R1 + R2 + 300
·
RF Amplifier Gain = ———————
R1 : Input Resistor
·
R1 + 300
The gain of RF amplifier can be adjusted by changing the value R1.
Unit (resistance : Ω)
No. 5689-11/14
LA7790M
4. Oscillator
The oscillator signal is divided by either 4 or 8, and supplied to the modulator as 0° and 90° switching signals. The
division mode can be selected using Band Switch 1 (pin 17).
Pin 17 = High → Modulation frequency = 1/4 oscillator frequency
Pin 17 = Low → Modulation frequency = 1/8 oscillator frequency
The oscillator requires an external coil and capacitors. Pins 14 & 15 should be DC coupled using a coil. A coil with
Qu of 30 or greater is required and the impedance between pins 14 and 15 is 6 kΩ. The value of the coupling
capacitors between pins 13 & 14 and pins 15 & 16 must be large enough so that the signal phase rotation is small.
Equivalent circuit of oscillator block
VCC
1 k
1 k
3 k
3 k
3.2 V
2.2 mA
13
14
15
16
Unit (resistance : Ω)
No. 5689-12/14
LA7790M
5. Oscillator Output
The output frequency of the oscillator is equal to or half of the output frequency of the modulator. The mode is set
using Band Switch 2 (pin 12).
Pin 12 = High → Oscillator output frequency = modulator frequency
Pin 12 = Low → Oscillator output frequency = 1/2 modulator frequency
6. Band Swtich
The input circuitry of Band Switch 1 (pin 17) and Band Switch 2 (pin 12) are the same. A low setting requires a
voltage of less than 1 V at the pin. A high setting requires a voltage between V –1 and V at the pin. Settings of
CC
CC
low or high generate currents of ±50 µA at pins 12 and 17.
Pin 12, 17 = High → Sink current = 50 µA
Pin 12, 17 = Low → Source current = 50 µA
Equivalent circuit of osc output and band switch blocks
VCC
20 k
20 k
LPF
from
from
Divider
Divider
OSC
OUTPUT
11
300
Band
switch2
12
40 k
20 k
20 k
1 mA
The input circuitry of band switch 1 is same.
Unit (resistance : Ω)
No. 5689-13/14
LA7790M
7. Digital ECL Circuit
To get the correct 0°/90° phase switching signal for the modulator, a divide-by-four dual flip-flop is employed as
shown in the following figure.
Band Switch 1 can be usded to expand the range of the modulation frequency. Band Switch 2 can be used to select
the frequency to output to an external PLL.
OSC
1/2
L
H
Band
switch
H/L
17
to Mudulator
90deg
Q
Q
D
D
Q
Q
D
D
0deg
CL
1/2
CL
1/2
H
L
1/2
1/2
1/2
12
Band
11
VCO
switch2 output
H/L
■ No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace
equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of
which may directly or indirectly cause injury, death or property loss.
■ Anyone purchasing any products described or contained herein for an above-mentioned use shall:
➀ Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and
distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all
damages, cost and expenses associated with such use:
➁ Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on
SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees
jointly or severally.
■ Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for
volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied
regarding its use or any infringements of intellectual property rights or other rights of third parties.
This catalog provides information as of May, 1998. Specifications and information herein are subject to change
without notice.
PS No. 5689-14/14
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