RF2670
10
8MHZ DUAL BASEBAND AGC WITH
PROGRAMMABLE LOW PASS FILTERING
Typical Applications
• Digital Cordless Telephones
• Inventory Tracking
• Secure Communication Links
• Wireless Security
• Wireless LANs
• Battery Powered Applications
Product Description
.157
.150
The RF2670 is a monolithic integrated circuit specifically
designed for direct conversion to baseband QPSK receivers. The part provides dual baseband amplifiers with a
70dB gain range (single pin analog input) and separate I
and Q RSSI. On-chip programmable baseband filters are
incorporated into each amplifier providing 1MHz, 2MHz,
4MHz, or 8MHz bandwidth with a 5-pole Bessel
response. I and Q output are available in digital or analog
form. The data comparators use a self generated DC reference to track DC offsets in the received signal. The
analog outputs have a 500mVpp swing with approximately 1.7V DC offset. A 2.0V reference voltage is also
available for A/D converters changing DC bias.
GaAs MESFET
SiGe HBT
Si CMOS
.012
.008
.344
.337
.025
.244
.228
.069
.053
8°MAX
0°MIN
.050
.016
.010
.008
10
Package Style: SSOP-24
Features
IF AMPLIERS
ü
GaAs HBT
Si Bi-CMOS
.010
.004
1
Optimum Technology Matching® Applied
Si BJT
.033
• I/Q Baseband Receivers
IN Q+
23
IN Q-
24
VCC1
VCC2
VCC3
• 10dB to 80dB Gain Range
20
5
8
• Digital and Analog Outputs
15 Q DATA
0-25 dB
0-20 dB
-12-+12
17dB
6 dB
18 IF OUT Q
21 DCFB Q
PD
11
BW SEL2
14
BW SEL1
13
• On-Chip Selectable IF Bandwidths
• Reference Voltage for A/D Converter
10 RSSI I
DC
Bias
17 VREF
16 RSSI Q
• 2.7V to 3.6V Operation
19 VGC
IN I+
2
IN I-
1
9 I DATA
7 IF OUT I
4 DCFB I
Ordering Information
RF2670
RF2670PCBA
Functional Block Diagram
Rev A4 010820
8MHz Dual Baseband AGC with Programmable Low
Pass Filtering
Fully Assembled Eval Board.
RF Micro Devices, Inc.
7625 Thorndike Road
Greensboro, NC 27409, USA
Tel (336) 664 1233
Fax (336) 664 0454
http://www.rfmd.com
10-45
RF2670
Absolute Maximum Ratings
Parameter
Ratings
Unit
Supply Voltage
Control Voltages
Input RF Level
Operating Ambient Temperature
Storage Temperature
-0.5 to +3.6
-0.5 to +3.6
+20
-40 to +85
-40 to +150
VDC
VDC
dBm
°C
°C
Parameter
Specification
Min.
Typ.
Max.
Caution! ESD sensitive device.
RF Micro Devices believes the furnished information is correct and accurate
at the time of this printing. However, RF Micro Devices reserves the right to
make changes to its products without notice. RF Micro Devices does not
assume responsibility for the use of the described product(s).
Unit
Baseband Amplifiers
Frequency Range
Voltage Gain
Noise Figure
0.01
8
MHz
83
-0.08
500
dB
dB
dB
dBm
dBm
mV
dB
V
dB/mV
mVPP
1
55
1.7
1.64
60
0.5 to 2.4
V
VPP
dB
V
1.5
2
77
Input IP3
Output DC offset
Gain Control Range
Gain Control Voltage Range
Gain Control Sensitivity
VGA Output Voltage
IF AMPLIERS
10
VGA DC Output Voltage
Output P1dB
RSSI Range
RSSI Output Voltage Compliance
Input Impedance
65
1.2
80
5
35
-65
+2
0
70
25
2.0
2.5
kΩ
Condition
T=25°C, VCC =3.0V
Minimum frequency is dependent upon input
blocking cap, DC feedback cap, and gain
setting. Recommended components yields a
minimum frequency of less than 10kHz.
At maximum gain setting
At minimum gain setting
At maximum gain setting
At minimum gain setting
Driving a 5kΩ load
At maximum gain setting
Maximum RSSI is 2.5V or VCC -0.3, whichever is less.
Differential
Integrated Filters
Characteristics
Five pole Bessel
Bandwidth
1, 2, 4, 8
Passband Ripple
Group Delay
Ultimate Rejection
MHz
1
100
50
dB
ns
80
dB
100
dB
MHz
ns
V
Five pole Bessel internal LPF.
Three pole external LPF.
Selectable from 1MHz, 2MHz, 4MHz, and
8MHz.
At 8MHz, increasing as bandwidth
decreases.
Data Amplifiers
Voltage Gain
Bandwidth
Rise and Fall Time
Logic High Output
8
2
5
VCC -0.3V
Logic Low Output
0.3
Hysteresis
40
V
5pF Load
Can sink/source 1mA and maintain these
logic levels.
Can sink/source 1mA and maintain these
logic levels.
mV
Power Down Control
Logical Controls “ON”
Logical Controls “OFF”
Control Input Impedance
Turn on Time
10-46
VCC -0.3V
0.3
>1
10
13
V
V
MΩ
ms
Voltage supplied to the input
Voltage supplied to the input
With recommended DC feedback cap
(270nF)
Rev A4 010820
RF2670
Parameter
Specification
Min.
Typ.
Max.
Unit
Condition
Power Supply
Voltage
Current Consumption
2.7
3.0
3.6
V
13
17
mA
VCC =3.0V; PD=High
1
µA
VCC =3.0V; Sleep Mode, PD=Low
IF AMPLIERS
10
Rev A4 010820
10-47
RF2670
IF AMPLIERS
10
Pin
1
2
3
4
5
Function
IN IIN I+
GND2
DCFB I
VCC2
6
7
8
9
GND3
IF OUT I
VCC3
I DATA
10
11
RSSI I
PD
12
13
GND1
BW SEL1
14
15
BW SEL2
Q DATA
16
17
18
19
20
RSSI Q
VREF
IF OUT Q
VGC
VCC1
21
22
23
24
DCFB Q
GND1
IN Q+
IN Q-
Description
Interface Schematic
Complementary input for the in-phase IF channel.
Input for the in-phase IF channel.
Ground for VCC2.
DC feedback capacitor for in-phase channel.
Power supply for VGA amplifier 3, differential to single-ended converter,
and post filter.
Ground for VCC3.
Analog signal IF output for in-phase channel.
Power supply for data amplifier.
Logic-level data output for the in-phase channel. This is a digital output
signal obtained from the output of a Schmitt trigger.
Received signal strength indicator for the in-phase channel.
Enable pin for the receiver circuits. PD >2.0V powers up all of the functions. PD<1.0V turns off all of the functions.
Ground for VCC1 for both the in-phase and quadrature channels.
Bandwidth select logic input. Pin 13 and pin 14 provide a two bit control
word for the setting of the IF bandwidth. See Table1. Additional filtering
should be used at the amplifiers to precisely control the 3dB bandwidth
of the system. See design information details about differential input filters.
See pin 13.
Logic-level data output for the quadrature channel. This is a digital output signal obtained from the output of a Schmitt trigger.
Received signal strength indicator for the quadrature channel.
Gain control reference voltage.
Analog signal IF output for quadrature channel.
Gain control voltage.
Power supply for bias circuits and VGA amplifiers for both the in-phase
and quadrature channels.
DC feedback capacitor for quadrature channel.
Ground for VCC1 for both the in-phase and quadrature channels.
Plus input for quadrature channel
Minus input for quadrature channel
Table 1: Bandwidth Selection Controls
BWSEL1
BWSEL2
0
0
1
1
0
1
0
1
10-48
IF-3dB
Frequency
1MHz
2MHz
4MHz
8MHz
Rev A4 010820
RF2670
Differential Filter Design Information
Butterworth Response
L
RS
C1
C2
L
RS
RL
RL
12
12
1
1
C1bw ⋅ --- ⋅ 10
C2bw ⋅ --- ⋅ 10
6
2
2
Lbw ⋅ RL ⋅ 10
C1 = -------------------------------------- ;C2 = -------------------------------------- ;L = ----------------------------------2 ⋅ π ⋅ fc ⋅ RL
2 ⋅ π ⋅ fc ⋅ RL
2 ⋅ π ⋅ fc
C1bw = 5.1672 ;C2bw = 15.4554 ;Lbw = 0.1377
RS
RS = 125 ;RL = 1000 ;------- = 0.125
RL
10
Differential LC Filter Component Values
(Butterworth Response)
IF AMPLIERS
100000
Component Value
10000
1000
C2 (pF)
100
C1 (pF)
10
L (µH)
1
1.E+05
1.E+06
1.E+07
Frequency
Rev A4 010820
10-49
RF2670
Differential Filter Design Information (Cont.)
Bessel Response
L
RS
C1
C2
L
RS
RL
RL
12
12
1
1
C1bw ⋅ --- ⋅ 10
C2bw ⋅ --- ⋅ 10
6
2
2
Lbw ⋅ RL ⋅ 10
C1 = -------------------------------------- ;C2 = -------------------------------------- ;L = ----------------------------------2 ⋅ π ⋅ fc ⋅ RL
2 ⋅ π ⋅ fc ⋅ RL
2 ⋅ π ⋅ fc
C1bw = 2.9825 ;C2bw = 15.4697 ;Lbw = 0.0860
RS
RS = 125 ;RL = 1000 ;------- = 0.125
RL
10
Differential LC Filter Component Values
(Bessel Response)
IF AMPLIERS
100000
Component Value
10000
1000
C2 (pF)
100
C1 (pF)
10
1
1.E+05
L (µH)
1.E+06
1.E+07
Frequency
10-50
Rev A4 010820
RF2670
Pin Out
IN-I 1
24 IN-Q
IN+I 2
23 IN+Q
GND2 3
22 GND1
DCFBI 4
21 DCFBQ
VCC2 5
20 VCC1
GND3 6
19 VGC
IF OUT I 7
18 IF OUT Q
VCC3 8
17 V REF
I DATA 9
16 RSSI Q
RSSI I 10
15 Q DATA
14 BW SEL2
GND1 12
13 BWSEL1
10
IF AMPLIERS
PD 11
Rev A4 010820
10-51
RF2670
Evaluation Board Schematic
(Download Bill of Materials from www.rfmd.com.)
J1
I IN
L1
10 µH
50 Ω µstrip
C5
100 nF
50 Ω µstrip
J4
Q IN
T2
L2
10 µH
C2
1 nF
C6
100 nF
DCFB I
1 IN I-
IN Q- 24
2 IN I+
IN Q+ 23
3 GND2
GND1 22
VCC
C3
1 nF
C4
220 pF
L4
10 µH
C8
100 nF
DCFB Q
C10
220 nF
DCFB Q 21
4 DCFB I
C9
220 nF
5 VCC2
VCC1 20
6 GND3
VGC 19
VCC
VGC
50 Ω µstrip
VREF
VREF 17
C11
47 nF
50 Ω µstrip
RSSI Q 16
9 I DATA
RSSI I
C13
68 pF
V IF EN
10 RSSI I
Q DATA 15
11 V IF EN
BW SEL2 14
12 GND1
BW SEL1 13
J5
IF OUT Q
50 Ω µstrip
IF OUT Q 18
7 IF OUT I
8 VCC3
J3
I DATA
L3
10 µH
T1
C1
220 pF
J2
IF OUT I
C7
100 nF
C12
68 pF
RSSI Q
J6
Q DATA
50 Ω µstrip
BW SEL2
BW SEL1
2670400-
P1
P1-1
10
IF AMPLIERS
L1-L4 and C1-C4 make two LPFs. The fc of the RF2670 is variable;
therefore the L and C components must be variable. The following
table gives recommended component values ("std" indicates standard
eval board value).
Desired BW
BW1, BW2 C1, C4 (pF) C2, C3 (pF) L1-L4 (µH)
700 kHz
0 0
330
1800
P1-3
P4-1
0 1
220 (std)
1000 (std)
10
2.8 MHz
1 0
100
470
4.7
P4-3
7.0 MHz
1 1
33
180
V IF EN
2
GND
3
DCFB I
P2-3
1
DCFB Q
P5-1
2
GND
3
VREF
P2-1
P4
22
1.4 MHz
P2
1
1
RSSI Q
2
GND
3
RSSI I
P5
P5-3
1
BW SEL2
2
GND
3
BW SEL1
2.2
P3
P3-1
C21
100 pF
C22
10 nF
C23
100 pF
C24
10 nF
C25
100 pF
C26
10 nF
C27
10 µF
P3-3
10-52
1
VCC
2
GND
3
VGC
Rev A4 010820
RF2670
Evaluation Board Layout
Board Size 3.0” x 2.0”
IF AMPLIERS
10
Rev A4 010820
10-53
RF2670
RF2670 IF Bandwidth Response
65.0
55.0
45.0
Gain (dB)
35.0
25.0
15.0
BW_SEL (0-0)
BW_SEL (0-1)
5.0
BW_SEL (1-0)
BW_SEL (1-1)
-5.0
-15.0
-25.0
-35.0
0.1
1.0
10.0
100.0
IF Frequency (MHz)
IF AMPLIERS
10
10-54
Rev A4 010820
RF2670
IIP3 versus Voltage Gain
Noise Figure versus Voltage Gain
(Non-Matched Input Z)
40.0
10.0
-40°C
-40°C
+25°C
0.0
+25°C
35.0
+100°C
+100°C
-10.0
30.0
Noise Figure (dB)
IP3 (dB)
-20.0
-30.0
-40.0
-50.0
25.0
20.0
15.0
10.0
-60.0
5.0
-70.0
-80.0
0.0
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
Voltage Gain (dB)
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
Voltage Gain (dB)
Voltage Gain versus Gain Control Voltage
90.0
-40°C
80.0
+25°C
+100°C
Voltage Gain (dB)
70.0
60.0
50.0
40.0
10
30.0
IF AMPLIERS
20.0
10.0
0.0
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
Gain Control Voltage (V)
Rev A4 010820
10-55
RF2670
IF AMPLIERS
10
10-56
Rev A4 010820