ATMEL U3770M

U3770M
CT2 I/Q Modulator and Clock Circuitry
Description
The U3770M is a quadrature modulator realized using
Atmel Wireless & Microcontrollers’ advanced 0.8 micron CMOS process. The IC is especially designed for
CT2 applications in conjunction with Atmel Wireless &
Microcontrollers’ RF/IF signal processor U2760B and a
CT2 baseband controller (i.e., AMD PhoXTM controller
Am79C4xx). Together with Atmel Wireless &
Microcontrollers’ PLL IC U2783B and the GaAs front
end U7001BG, a complete CT2 chip set is available.
Electrostatic sensitive device.
Observe precautions for handling.
Features
D Programmable 0.8/1.6-MHz quadrature-modulated
carrier generation
D More than 26 dB LO and sideband suppression
D 18.432 MHz CMOS level clock generation
D Supply-voltage range 2.7 V to 3.3 V
D Low power consumption, typically 12 mW
D SO16 package or die form
Block Diagram
RRef in 12.8 MHz
LF
2
DIV / 25
Phase
512 kHz comparator
Amp.
VDD
DGND
AGND
PROG
TST
Qin
QBin
Iin
IBin
95 9881
11
VCO
512 kHz
DIV / 36
14
CLK out
9
MOD out
18.432 MHz
3
4
13
DIV / 2
or
DIV / 4
12
10
6.4 MHz
3.2 MHz
Dual DFF
6
5
8
7
1, 15, 16
DNC
Figure 1. Block diagram
Ordering Information
Extended Type Number
Package
U3770M-MFP
SO16
Tube
U3770M-MFPG3
SO16
Taped and reeled
Rev. A3, 07-Sep-00
Remarks
1 (6)
U3770M
Functional Description
The U3770M has been designed to reduce power consumption and cost of CT2 devices. An innovative CMOS
I/Q modulator with extremely low current provides all the
advantages of I/Q modulation:
– No requirement for FM deviation tuning
– Eliminates the Gaussian filter
– Simplifies the power ramping control
The modulated output carrier can be programmed to be
0.8 MHz or 1.6 MHz by the PROG control pin.
The typical supply voltage is 3 V @ 4 mA.
To reduce overall system cost, an internal PLL generates
an 18.432-MHz clock signal from the system’s 12.8-MHz
reference oscillator. This way, only one crystal oscillator
is needed in the complete CT2 device.
Internally, the 12.8-MHz reference signal is fed into a
shaping amplifier and then into two logic dividers, to generate a 512-kHz and a programmable 3.2-MHz or
6.4-MHz clock. This clock is divided by 4 by two D flipflops. The flip-flop outputs drive the four analog switches
in quadrature. The local oscillator (LO) supression mixer
consists of a pair of analog switches. make a local oscillator (LO) suppression mixer. By summing the other pair
outputs the suppression (both LO and side tone) is
<–26 dBc.
The 512-kHz clock drives a frequency synthesizer. The
VCO runs at a fixed frequency of 18.432 MHz. The VCO
control voltage (LF pin) controls the VCO frequency.
Pin Description
Pin
Symbol
n.c.
1
16 n.c.
2
FRef in
External 12.8-MHz reference
frequency input
FRef in
2
15 n.c.
3
VDD
Supply voltage
4
DGND
Digital ground
5
QBin
Analog switch input
6
Qin
Analog switch input
7
IBin
Analog switch input
8
Iin
Analog switch input
9
MODout
10
TST
11
LF
12
PROG
PROG = 0, 1.6-MHz mode
PROG = 1, 0.8-MHz mode
13
AGND
Analog ground
14
CLKout
Digital CMOS clock output
18.432 MHz
1, 15,
16
n.c.
VDD 3
14 CLKout
DGND 4
13 AGND
QB 5
12 PROG
Q 6
IB
I
11 LF
10 TST
7
9 MODout
8
95 9930
Figure 2. Pinning
2 (6)
Function
Modulator output signal
Test input, must be connected to
GND (only factory use)
PLL loop filter
Not connected
Rev. A3, 07-Sep-00
U3770M
Absolute Maximum Ratings
Stresses at or above those listed may cause permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in this data sheet is not implied. Exposure
to absolute maximum rating conditions for extended periods may affect device reliability.
Parameters
Symbol
Value
Unit
VDD
6
V
Modulator input voltages
I, IB, Q, QB
–0.5 to VDD
V
Reference frequency input
FRef in
–0.5 to VDD
V
Ambient temperature
Tamb
–40 to +85
°C
Storage temperature
Tstg
–65 to +150
°C
Junction temperature
Tj
Tj < Tamb +10
°C
Symbol
Value
Unit
Supply voltage
VDD
3 " 10%
V
Ambient temperature
Tamb
–5 to +70
°C
Junction temperature
Tj
Tj < Tamb +5
°C
Storage temperature
Tstg
–40 to +125
°C
Supply voltage
Operating Range
Parameters
Electrical Characteristics
Test conditions (unless otherwise specified) related to test circuit
VS = 3 V, VBIi, VBIi and VBQi, VBQi = 1 VPP single ended, oscillator frequency FRef in = 12.8 MHz, Tamb = –5 to +70°C
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
2.7
3
3.3
V
Supply-voltage range
Pin 3
VDD
Supply current
Pin 3
IDD
FRef in
Pin 2
4
mA
Input voltage
VF Ref in
150
mVPP
Input impedance
ZF Ref in
100
kW
I, Q inputs
Pins 5, 6, 7 and 8
Input voltage
Single ended
VIin, Qin
1
VPP
Input impedance
Single ended
ZIin, Qin
20
kW
Input frequency
FIin, Qin
18
kHz
External bias voltage
VIB, QB
1.5
V
VMod out
70
mVRMS
LO sub
SB sub
ZMod out
–26
dBc
5
kW
FCLK out
18.432
MHz
MODout
Output level
Pin 9
1)
Unloaded
LO and sideband suppression
Output impedance
CLKout
Pin 14
Output frequency
Output-voltage swing
Rev. A3, 07-Sep-00
@ load = 20 pF
VCLK out
1.8
V
3 (6)
U3770M
Note 1)
4 (6)
The output signal contains some harmonics to be filtered by an external lowpass filter
Rev. A3, 07-Sep-00
U3770M
Test Circuit
47 nF
4.7 nF
R Ref in
12.8 MHz
LF
2
VDD
Phase
comparator
512 kHz
Amp
VCO
14
CLK out
DIV / 36
512 kHz
18.432 MHz
4
DGND
13
AGND
12
PROG
95 9967
11
DIV / 25
3
22 W
DIV / 2
or
DIV / 4
6.4 MHz
Dual DFF
3.2 MHz
10
TST
9
MOD out
6
5
QB in
Q in
1 nF
1 kW
8
I in
1 nF
1 kW
7
IB in
1 nF
1 kW
1 nF
1 kW
Figure 3. Test circuit
Rev. A3, 07-Sep-00
5 (6)
U3770M
Package Information
Package: SO16
3.
We reserve the right to make changes to improve technical design and may do so without further notice.
Parameters can vary in different applications. All operating parameters must be validated for each customer
application by the customer. Should the buyer use TEMIC Semiconductors products for any unintended or
unauthorized application, the buyer shall indemnify TEMIC Semiconductors against all claims, costs, damages,
and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with
such unintended or unauthorized use.
Data sheets can also be retrieved from the Internet:
http://www.temic–semi.com
TEMIC Semiconductor GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany
Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423
6 (6)
Rev. A3, 07-Sep-00