1
MGCT03
Transmit Circuit for TDMA/AMPS
DS5418
ISSUE 1.0
December 2000
Ordering Information
MGCT03/KG/QP1S
MGCT03/KG/QP1T
The MGCT03 circuit is designed for use in dual
band, dual mode cellular 900MHz/PCS1900MHz
mobile phones. It can be used for TDMA/AMPS. The
MGCT03 is compatible with baseband and mixed
signal interface circuits from Zarlink Semiconductor
and other manufacturers.
System costs have been kept to a minimum by
removing the requirement for an additional SAW filter
in the transmit IF path. The AGC has been split
between RF and IF sections to reduce noise and a
low pass filter has been included before the IF
variable gain amplifier to remove spurious products
produced in the modulator.
For CDMA systems the MGCT04 is recommended.
Figure 1 - MGCT03 Block Diagram
Features
Dual RF Ports for 900MHz and 1900MHz
AGC Amplifier with 90dB of Variable Gain, Fully
Compensated for Temperature
On-chip Active Filter. Removes the
Requirement for External IF SAW Filter
High Power 900MHz and 1900MHz Output
Stages
Quadrature Modulator
Applications
Transmit Modulator and Up-converter in TDMA/
AMPS Mobile Phones
Absolute Maximum Ratings
Supply voltage (V
CC
)
4V
Control input voltage
-0.6V to VCC + 0.6V
Storage temperature, T
STG
-55C to +125C
Operating temperature
-40C to 100C
Max Junction Temperature (T
J
) 150C
RF900
2/4 AND
PHASE
SHIFT
IF VGA
ALL PASS
PHASE
SHIFT
NETWORK
RF VGA
RF190
RF900
RFDEG1
OSC
BUFFER
VGA CONTROL
VHF OSC IN
Q IN
Q IN
I IN
I IN
17
18
20
19
11
12
2
AGC
UHF
OSCILLATOR
INPUT SELECT
CONTROL LOGIC
POWER CONTROL
1
CP2
CP1
CP0
27
28
23
25
LO 2GHz
LO 1GHz
1900 MHz
OUTPUT DRIVER
900 MHz
OUTPUT DRIVER
7
6
3
4
9
8
V
REF
BIAS
BUFFER
VHF OSC BIAS
SSB MIXER
RF190
RFDEG2
MGCT03
2
Pin
Signal Name
Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
CP2
AGC
RF DEG1
RF DEG2
RF GND
RF 1900
RF1900
RF 900
RF 900
VCO GND
VHF OSC BIAS
VHF OSC IN
VCO V
CC
NC
GND
Q IN
Q IN
GND
I IN
I IN
V
CC
UHF V
CC
LO 2GHZ
GND UHF
LO 1GHZ
RF V
CC
CP1
CP0
Control pin 2. See Tables 4 and 5 for function
Control voltage for IF and RF variable gain amplifiers
Connection to external inductor to control gain of power amplifiers
Connection to external inductor to control gain of power amplifiers
Ground connection to RF circuits
Inverse output from 1900MHz differential output driver
Output from 1900MHz differential output driver
Inverse output from 900MHz differential output driver
Output from 900MHz differential output driver
Ground connection for VHF oscillator
Switched bias voltage for external VHF oscillator
Input from external VHF oscillator
Positive supply to VHF oscillator
Not used
Ground connection
Q input
Q input
Ground connection
I input
I input
Positive supply connection
Positive supply to UHF oscillator input buffers
2GHz local oscillator input
Ground connection to UHF oscillator input buffers
1GHz local oscillator input
Positive supply connection to RF circuits
Control pin 1. See Tables 4 and 5 for function
Control pin 0. See Tables 4 and 5 for function
Table 1 - Pin Assignments
CP2
AGC
RF DEG1
RF DEG2
RF GND
RF 1900
RF 1900
RF 900
RF 900
VCO GND
VHF OSC BIAS
VHF OSC IN
VCO V
CC
NC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CP0
CP1
RF V
CC
LO 1GHz
UHF GND
LO 2GHz
UHF V
CC
V
CC
I IN
I IN
GND
Q IN
Q IN
GND
MGCT03
QSOP28
Figure 2 - Pin Connections - top view
MGCT03
3
Electrical Characteristics
Test conditions (unless otherwise stated): Tamb = -30C to +70C, V
CC
= 27V to 36V. UHF LO level = -15dBm
(both bands), I, Q input = 1.4 volts p.p, test frequency = 849MHz (900 output) and 1910MHz (1900
output).These characteristics are guaranteed by either production test or design. They apply within the
specified ambient temperature and supply voltage ranges unless otherwise stated.
Characteristics
Value
Units
Conditions
Min.
Typ.
Max.
Supply current
Sleep current
Standby mode supply current
Total supply current
Standby to operating mode
switching time
Logic inputs
Logic high voltage
Logic low voltage
V
CC
-0.6
0
8
118
75
10
152
10
VCC
08
A
mA
mA
s
V
V
All circuits off
See Tables 4 and 5
Maximum power PCS mode
Table 2 - DC Characteristics
Characteristics
Value
Units
Conditions
Min.
Typ.
Max.
I and Q modulator
I and Q input voltage level
1.0
1.4
2.0
Vpp
Differential
I and Q common mode voltage
1.2
V
I and Q differential input
resistance
13.5
k
I and Q input bandwidth
2.5
MHz
IF Vector offset
30
dB
SSB rejection
30
dB
VHF oscillator input and divider
Input drive level
22
40
70
mVrms
From external VHF osc. via
matching network
VHF oscillator bias voltage
1.2
V
Variable gain amplifiers
IF amp. operating frequency range
50
200
MHz
RF amp. operating frequency
range
750
2000
MHz
Gain control range
60
dB
Control voltage for minimum gain
0.1
V
Control voltage for maximum gain
2.6
V
AGC control voltage slope
33
60
dB/V
Table 3 - AC Characteristics
MGCT03
4
Characteristics
Value
Units
Conditions
Min.
Typ.
Max.
SSB mixer and UHF oscillator
inputs
SSB rejection
18
dB
Cellular band LO input level
-15
-10
-5
dBm
From external UHF osc. via
matching network
PCS band LO input level
-15
-10
-5
dBm
From external UHF osc. via
matching network
Cellular band local oscillator input
frequency. (LO 1GHz)
850
1100
MHz
PCS band local oscillator input
frequency (LO 2GHz)
1500
2150
MHz
900MHz RF output stage
Specifications assume 50 ohm
load driven via a matching network
(Fig. 6)
RF amplifier operating frequency
range
824
849
MHz
Output power
+8
+19
dBm
Note 1
ACPR (TDMA)
-45
-30
dBc
Pout = +8dBm, Offset = 30kHz
-90
-60
dBc
Pout = +8dBm, Offset = 60kHz
Output power AMPS
+10
+14
+19
dBm
Note 2
Receive band noise
(869 - 894MHz)
-123
-121
dBm/
Hz
ftx = 849 MHz Pout = +8dBm
Spurious Outputs
LO Leakage
-18
dBc
Note 2, Pout = +8dBm
LO Leakage
-14
dBm
V
CC
= 3V, T = 25C Pout = +8dBm
Image Rejection
-18
dBc
Note 2, Pout = +8dBm
Other Spurii
-20
dBm
Note 3
1900MHz RF output stage (PCS)
Specifications assume 50 ohm
load driven via a matching network
(Fig. 5)
RF amplifier operating frequency
range
1850
1910
MHz
Output power
+8
+18
dBm
Note 1
ACPR (TDMA)
-45
-30
dBc
Pout = +8dBm, Offset = 30kHz
-90
-60
dBc
Pout = +8dBm, Offset = 60kHz
Receive band noise
(1930 - 1990 MHz)
-123
-121
dBm/
Hz
ftx = 1910MHz, Pout = +8dBm
Receive band noise
(1930 - 1990MHz)
-128
-125
dBm/
Hz
ftx = 1910MHz, Pout = +3dBm
V
CC
= 3V, T =25C
Table 3 - AC Characteristics (continued)
MGCT03
5
Spurious Outputs
LO Leakage
-18
dBc
Note 2, Pout = =8dBm
LO Leakage
-14
dBm
V
CC
= 3V, T = 25C Pout = +8dBm
Image Rejection
-18
dBc
Note 2, Pout = +8dBm
Other Spurii
-20
dBm
Note 3
Characteristics
Value
Units
Conditions
Min.
Typ.
Max.
Table 3 - AC Characteristics (continued)
Notes:
1. V (I/Q) = 1.4V differential, VHF LO = 22mV rms, UHF LO = -15dBm, VGA = 2.6volts
2. V (I/Q) = 1.4 V dc differential, VHF LO = 22mV rms, UHF LO = -15dBm
3. Frequency range 10MHz to 10*ftx except Rx and Tx bands
Circuit Description
General
The MGCT03 circuit is designed to provide the
transmit function in dual band dual mode IS136/
AMPS mobile phones. The circuit contains the
following blocks:
1. Quadrature modulator
2. Active IF low pass filter
3. IF variable gain amplifier
4. Single sideband mixer with external UHF
oscillator inputs
5. RF variable gain amplifier
6. 900MHz and 1900MHz high power output driver
stages
7. Power and mode control logic
Quadrature Modulator
I and Q data from a baseband circuit such as the
Zarlink Semiconductor MGCM01 or MGCM02 circuit
is applied to the I and Q inputs of the quadrature
modulator to produce the intermediate frequency by
mixing with the local oscillator frequency from the
VHF VCO. The control inputs can select either a
divide by two or divide by four function between the
VHF VCO and the quadrature modulator giving a
choice of possible intermediate frequencies.
VHF Oscillator Input Oscillator Bias and
Divider
An external VHF oscillator circuit is AC coupled to
the VHF oscillator input to drive the quadrature
modulator. An oscillator bias circuit is included on
the chip so that the external VHF oscillator transistor
can be switched off using the control inputs. The bias
voltage is switched off in either of the sieep
conditions shown in Tables 4 and 5.
Active Low Pass Filter
The output from the quadrature modulator is passed
to the active low pass filter which attenuates wide
band noise and spurious outputs.
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