CX74036
IS-136 Receive RF IC for TDMA and AMPS Applications
Conexant’s CX74036 receive RF IC is an advanced, highly integrated and high
performance, triple-mode, dual-band IC for IS-136 compliant cellular radio
applications and is designed in an advanced 28 GHz Ft BiCMOS process. In the
800 MHz cellular band, the CX74036 is designed to operate in both the Time
Division Multiple Access (TDMA) mode and Advanced Mobile Phone System
(AMPS) mode. In the 1900 MHz Personal Communications System (PCS) band,
the device operates in the TDMA mode.
The CX74036 embodies all the necessary functions for a radio receiver system
except for the RF and Intermediate Frequency (IF) filters and RF Local Oscillator
(LO) sources. The device front-end section has two Low Noise Amplifier (LNA) and
mixer pairs, one for the 800 MHz band and the other for the 1900 MHz band. A
common path is taken from the first IF mixer output to the demodulator output.
The CX74036 48-pin, 7x7 Land Grid Array (LGA) package pin configuration is
shown in Figure 1. A block diagram of the CX74036 is shown in Figure 2.
Features
•
•
•
•
•
•
Front-end to baseband in one IC
Inphase and Quadrature (I/Q) demodulator
3 V supply operation
Low current consumption
LNA gain switch with current reduction
IF LO synthesizer with Voltage Controlled
Oscillator (VCO) (requires external tank)
•
70 dB Variable Gain Amplifier (VGA) dynamic
range
•
Low Noise Figure (NF) and high 3rd order Input
Intercept Point (IIP3) mixers
Applications
•
Cellular and/or PCS band phones
•
TDMA and/or AMPS mode phones
•
Portable battery powered radio equipment
VCC2_LNAH
VCC2_LNAL
VCC1_LNA
LNA_INH
LNA_INL
LNA_O H
LNA_O L
EXT_LO
39
LNA_G
MXIH
MIXIL
BAND
CHIP_EN
LO IH
LO IL
VCC_MX
STANDBY
IQ /IF
MXO UT+
MXO UT-
MX2I+
1
2
3
4
5
6
7
8
9
10
11
12
13
48
47
46
45
44
43
42
41
40
38
IF_O +
NC2
NC1
37
36
35
34
33
32
31
30
29
28
27
26
IF_O -
Q-
Q+
I-
I+
EXT_LO IN
VCC_VCO
VCO -
VCO +
VCC_SYN
LP_FIL
REFIN
DATA
14
15
16
17
18
19
20
21
22
23
24
25
MX2I-
VG AI-
IFBYPASS
VG AI+
Vvga
FB_CAP
VCC_VG A
MX2O UT
VCC_IF
LATCH_EN
CLK
101105A-1_082500
Figure 1. CX74036 48-Pin, 7x7 LGA Package Pin Configuration
Data Sheet
Conexant – Proprietary
Data Subject to Change
Doc. No. 101105A
October 17, 2000
CX74036
Receive RF IC
Im age Rejection Filter
1st IF SAW
450 KHz
Vvga
Vcc
Standby
CLK
Interface
Power
M anagem ent
DATA
EN
LNA G ain
Band Select
Power Down
VCO /REFIN
PCS RF In
1st IF LO
CX74036
RX RFIC
VHF
Synth
I
÷P
÷ 4
IQ /
IF
Q
IF O ut
IF Buffer
Cell RF In
Cell LO
PCS LO
19.44 M Hz
Ext.1.8 M Hz
Im age Rejection Filter
101105A-2_101200
Figure 2. CX74036 Functional Block Diagram
Technical Description
Low Noise Amplifiers:
The CX74036 contains two
independent LNAs for the cellular and PCS bands. The gain of
both LNAs can be switched off to a loss mode via one command
line interface. Only one LNA is powered at any given time.
Control is done by an external band-select control signal. The
input and output matches are external to the chip. The LNAs’
parameters, Noise Figure (NF), and gain are chosen to provide
an excellent balance between system sensitivity and IIP3
requirements to achieve maximum dynamic range. Both LNA
outputs are ported off-chip to allow for image filtering before
being fed to the RF mixer inputs.
RF Mixers:
The mixers are designed to operate with a low LO
input power level of –10 dBm. This eliminates the requirement of
buffer amplifiers for the external VCO. Cellular band mixer high
gain and low NF performance allow for the cellular LNA gain to
be lower, which saves current consumption. Both mixers are
designed to provide high suppression of one-half IF response.
The outputs of both mixers share a common interface path to
the external IF Surface Acoustic Wave (SAW) filter, which
reduces complexity and cost. The RF mixer load configuration is
shown in Figure 3. Inductors can be Surface Mount Multilayer
Chip (SMMC) components.
First IF Mixer:
This mixer begins the common signal path for
both cellular and PCS band modes. Input and output impedance
are set to values that are close to the most commonly available
SAW and ceramic filters.
Vcc
330 nH
1200 pF
+
RF M ixers
Output
10 K
Ω
to IF SAW
Filter
-
1200 pF
330 nH
Vcc
101105A-3_101100
Figure 3. RF Mixer Load Configuration
Variable Gain Amplifier:
The VGA itself provides 70 dB of
dynamic range to satisfy the high system dynamic range
requirement. With the inclusion of the LNA gain switch, the
system dynamic range is extended to more than 95 dB.
I/Q Demodulator:
Using digital circuitry generates a stable
quadrature LO signal, on-chip direct connection to the VGA
output, on-chip LO source, and lowpass filtering for each
channel. This, in turn, provides a high performance I/Q
demodulator with very low amplitude and phase offsets. The
output signal quality is compatible with many baseband interface
requirements.
101105A
October 17, 2000
2
Conexant – Proprietary
Data Subject to Change
Receive RF IC
CX74036
VHF Synthesizer and Oscillator:
The on-chip VHF synthesizer
and an oscillator with an added external tank circuit generate
the required second IF LO signal for conversion down to the
standard second IF signal. A programmable divide circuit is also
included to generate the LO for the I/Q demodulator. Depending
on the frequency plan used, an option is provided to inject an
external LO source for the I/Q demodulator.
Control Logic Truth Table.
The Control Logic Truth Table is
shown in Table 1.
3-Wire Bus Programming.
The 3-wire bus programming data
is included in Table 2. The 3-wire programming data pattern
diagram is shown in Figure 4.
Electrical and Mechanical Specifications ________________
The signal pin assignments, names, and descriptions are found
in Table 3. Absolute maximum ratings are provided in Table 4,
the recommended operating conditions are specified in Table 5.
Electrical characteristics are shown in Table 6.
Figure 6 provides the 48-Pin, 7x7 LGA package dimensions.
ESD Sensitivity
The CX74036 is a static-sensitive electronic device. Do not
operate or store near strong electrostatic fields. Take proper
ESD precautions.
Table 1. Control Logic Truth Table
Mode
Active, Low Band, LNA High Gain, IQ
Active, High Band, LNA High Gain, IQ
Active, Low Band, LNA Low Gain, IQ
Active, High Band, LNA Low Gain, IQ
Active, Low Band, LNA High Gain, IF
Active, High Band, LNA High Gain, IF
Active, Low Band, LNA Low Gain, IF
Active, High Band, LNA Low Gain, IF
Standby
External LO Mode
Sleep
LNA_G
1
1
0
0
1
1
0
0
---
---
---
BAND
0
1
0
1
0
1
0
1
---
---
---
CHIP_EN
1
1
1
1
1
1
1
1
0
1
0
STANDBY
1
1
1
1
1
1
1
1
1
---
0
IQ/IF
0
0
0
0
1
1
1
1
---
---
---
LO_EXT
1
1
1
1
1
1
1
1
1
0
0
Note.
Synthesizer prescaler and charge pump can be turned off via programming from the 3-wire bus. This mode can be used when driving
the IF Mixer with an external synthesizer.
Table 2. 3-Wire Bus Programming Data
Bit Number
00
01 – 08
09 – 12
13 – 23
24
25 – 32
33 – 34
35
Function
Select VCO or Reference Input to Programming Counter
Synthesizer M Counter Programming, MB0 – MB7
Synthesizer A Counter Programming, AB0 – AB3
Synthesizer Reference Counter Programming, RB0 – RB10
Charge Pump Polarity
Programmable M Counter Programming, M2B0 – M2B1
Programmable A Counter Programming, A2B0 – A2B1
Synthesizer Power down (For External Synthesizer Mode)
Programming
“0” = Reference Input
“1” = VCO Input
“0” = Ground Referenced Varactor
“1” = VCC Referenced Varactor
“0” = Internal Synthesizer
“1” = External Synthesizer
101075A
October 17, 2000
Conexant – Proprietary
Data Subject to Change
3
CX74036
Receive RF IC
M SB
35
SPD
34
A2B1
33
A2B0
32
M 2B7
31
M 2B6
30
M 2B5
29
M 2B4
28
M 2B3
27
M 2B2
26
M 2B1
25
M 2B0
24
CPP
23
RB10
22
RB9
RB8
21
RB7
20
RB6
19
RB5
18
LSB
17
RB4
RB3
16
RB2
15
RB1
14
RB0
13
AB3
12
AB2
11
AB1
10
AB0
09
M B7
08
M B6
07
06
M B5
05
M B4
04
M B3
03
M B2
02
M B1
01
M B0
00
VRS
00 = First bit shifted in (LSB)
35 = Last bit shifted in (M SB)
VRS = Select VCO or Reference Input to Programm able Counter
"0" = Reference Input
"1" = VCO Input
M B0 - M B7: Program m ing for Synthesizer M Counter: M B0 (LSB), M B7 = (M SB)
AB0 - AB3: Program m ing for Synthesizer A Counter: AB0 (LSB), AB7 = (M SB)
RB0 - RB10: Program m ing for Synthesizer R Counter: RB0 (LSB), RB10 = (M SB). CPP = Change Pum p Polarity,
"0" = Ground Reference
M 2B0 - M 2B7: Program m ing for LO Divider M Counter: M 2B0 (LSB), M 2B7 = (M SB)
A2B0 - A2B7: Program m ing for LO Divider A Counter: A2B0 (LSB), A2B1 = (M SB)
SPD = Synthesizer Power Down (for External Synthesizer M ode)
"1" = Internal Synthesizer,
"0"= External Synthesizer
101105A-4_101200
Figure 4. 3-Wire Programming Data Pattern
Table 3. Signal Pin Names and Definitions (1 of 2)
Pin No.
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
Signal Name
LNA_G
MXIH
MIXIL
BAND
CHIP_EN
LOIH
LOIL
VCC_MX
STANDBY
IQ/IF
MXOUT+
MXOUT-
MX2I+
MX2I-
VCC_IF
IFBYPASS
MX2OUT
Vvga
VCC_VGA
VGAI-
VGAI+
FB_CAP
LATCH_EN
CLK
DATA
REFIN
LNAs gain control command
1900 MHz band mixer Input
800 MHz band mixer Input
Description
800 MHz/1900 MHz band select command
Chip power down select command
1900 MHz RF mixer LO input
800 MHz RF mixer LO input
RF mixer VCC
Control signal to enable RF LO buffers and VHF synthesizer
I/Q or IF output select command
RF mixer output. Open Collector.
RF mixer output. Open Collector.
IF mixer input
IF mixer input
IF section VCC
IF mixer bias decoupling
IF mixer output
Analog voltage input for VGA gain control
VGA section VCC
VGA input
VGA input
VGA DC feedback filter capacitor connection
Enable input line for internal synthesizer programming
Serial clock input line for internal synthesizer programming
Serial data input line for internal synthesizer programming
19.44 MHz reference oscillator input. Requires VCC/2 DC bias.
4
Conexant – Proprietary
Data Subject to Change
101105A
October 17, 2000
Receive RF IC
Table 3. Signal Pin Names and Definitions (2 of 2)
Pin No.
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
CX74036
Signal Name
LP_FIL
VCC_SYN
VCO+
VCO-
VCC_VCO
EXT_LOIN
I+
I–
Q+
Q–
IF_O–
IF_O+
EXT_LO
NC1
LNA_INH
LNA_INL
NC2
VCC1_LNA
VCC2_LNAL
VCC2_LNAH
LNA_OL
LNA_OH
Synthesizer section VCC
Description
IF PLL external loop filter connection
IF VCO external tank circuit connection
IF VCO external tank circuit connection
VCO section VCC
External LO input for quadrature detector. Requires VCC/2 DC bias.
I Channel data output
I Channel data output
Q Channel data output
Q Channel data output
Buffered IF output
Buffered IF output
Programmable counter ON/OFF control signal for choosing between
Internal and External demodulator LO.
No connect
1900 MHz band LNA input
800 MHz band LNA input
No connect
Bias VCC for LNAs
VCC for cellular band LNA.
VCC for PCS band LNA.
800 MHz band LNA output. Requires external matching and AC coupling.
1900 MHz band LNA output. Requires external matching and AC coupling.
Table 4. Absolute Maximum Ratings
Parameter
Supply voltage
Input voltage range
LNA input power
Power dissipation
Ambient operating temperature
Storage temperature
–40
–40
Symbol
VCC
Minimum
–0.3
–0.3
Typical
Maximum
+3.6
VCC
+5
600
+85
+125
Units
V
V
dBm
mW
°C
°C
101105A
October 17, 2000
Conexant – Proprietary
Data Subject to Change
5
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