U2796B
Rev. A3, 10-Oct-00 1 (10)
2-GHz Single-Balanced Mixer
Description
The U2796B-FP is a 2-GHz down-conversion mixer for
telecommunication systems, e.g. cellular radio, CT1,
CT2, DECT, PCN, using Atmel Wireless &
Microcontrollers’ advanced bipolar UHF technology.
The U2796B is well suited for the receiver portion of the
RF circuit. Single-balanced structure has been chosen for
best noise performance and low current consumption.
The IIP3 is programmable.
Electrostatic sensitive device.
Observe precautions for handling.
Features
Supply-voltage range: 2.7 V to 5.5 V
Excellent isolation characteristics
Low current consumption: 3.2 mA without RIP3
IIP3 programmable
Input frequency operating range up to 2 GHz
RF characteristic nearly independent of
supply voltage
Benefits
Stand-alone product
Low current consumption extends talk time
3-V operation requires only small space for batteries
Block Diagram
Duty cycle
control loop
Buffer
Mixer
Voltage
regulator
2
3
5
4
IF
S
V
6,8 7
LO 193 7758 e
i
O
IFO
RFI
BPC
Figure 1. Block diagram
Ordering Information
Extended Type Number Package Remarks
U2796B-MFP SO8 Tube
U2796B-MFPG3 SO8 Taped and reeled
U2796B
Rev. A3, 10-Oct-002 (10)
Pin Description
1
2
3
45
6
7
8
GND
VS
RFi
BPC
IFO
LOi
IFO
GND
93 7820 e
Figure 2. Pinning
Pin Symbol Function
1 VSSupply voltage
2 RF RF input and IIP3 programming
port
3 BPCBypass capacitor
4 IFo IF output
5 IFo IF output
6 GND Ground
7 LOiLocal oscillator input
8 GND Ground
Absolute Maximum Ratings
Parameters Symbol Value Unit
Supply voltage Pin 1 VS6 V
Input voltage Pins 2, 3, 4, 5 and 7 Vi0 to VSV
Junction temperature Tj125 °C
Storage temperature Tstg –40 to +125 °C
Operating Range
Parameters Symbol Value Unit
Supply-voltage range Pin 1 VS2.7 to 5.5 V
Ambient temperature Tamb –40 to +85 °C
Thermal Resistance
Parameters Symbol Value Unit
Junction ambient SO8 RthJA 175 K/W
Electrical Characteristics
Test conditions (unless otherwise specified):
VS = 3 V, fLO = 900 MHz; IM = 1.2 mA, Tamb = 25°C. System impedance ZO = 50 Ω
Parameters Test conditions / Pin Symbol Min. Typ. Max. Unit
Supply voltage Pin 1 VS2.7 5.5 V
Supply current RIP3 = , Pin 1 IS2.8 3.2 3.7 mA
Conversion power gain RL = 3 kΩ, RIP3 =
fLO = 900 MHz PGC9 dB
Figure 4 fLO = 1700 MHz
fIF = 45 MHz 9
U2796B
Rev. A3, 10-Oct-00 3 (10)
Electrical Characteristics (continued)
Parameters Test conditions / Pin Symbol Min. Typ. Max. Unit
Isolation
LO spurious at RFin PiLO = –10 dBm
Figure 5 Pin 7 to 2 ISLORF –35 dBm
RF to LO
Fi 6
PiRF = –25 dBm Pin 2 to 7
fLO = 900 MHz ISRFLO 30 40 dB
Figure 6 fLO = 1700 MHz 20
Operating frequencies
RF frequency Pin 2 RFi2000 MHz
LOin frequency Pin 7 LOi2000 MHz
IFout frequency Pins 4 and 5 IFo300 MHz
Input level
RF input (–1 dB comp.) RL = 50 Ω, Pin 2 PiRF –15 dBm
3rd-order intercept
point PiLO = –10 dBm, RIP3 =
Figure 2 Pin 2 IIP3 –4 dBm
LO input Pin 7 PiLO –6 0 dBm
Impedances
RF input Pin 2 ZiRF 25 Ω
LO input Pin 7 ZiLO 50 Ω
IF output Pins 4 and 5 ZoIF 10
kΩ// 0.9
pF
Noise figure (DSB)
i
PiLO = 0 dBm, RL 3 kΩ
fLO = 900 MHz NF50 9dB
Figure 7 fLO = 1700 MHz 12
Voltage standing wave
ratio LO Pin 7 VSWR-
LO
1.3 2
Note: IM = Internal mixer current (see figure 3)
0 400 800 1200 1600
1.0
1.5
2.0
2.5
3.0
3.5
I ( mA )
M
RE ( )
2000
93 7825 e
Figure 3. Mixer current (IM) versus RE
12
–7
–4
–1
2
5
8
IIP3 ( dBm )
IM ( mA )
3
93 7827 e
Figure 4. Third-order input intercept IIP3 point versus IM
U2796B
Rev. A3, 10-Oct-004 (10)
LO buffer
LO 7
3
2
E
R
IF
54
RF M
I
93 7759 e
i
O
i
Figure 5. Mixer circuitry
8765
1234
C
2
3
C
IP3
R
1
Spectrum
analyzer
Hp 70908 A
R = 50
i
N
C4
1
C
LO
R = 50
i
10 dB
LO
10 dB
i
1. RF
generator
R = 50
10 dB
10 dB
i
2. RF
R = 50
RF
Power
splitter
S
V
r
C
U2796B
93 7760 e
1
f = 958.5 MHz f = 900 MHz
LO
f = 958.55 MHz
2
–10 dBm
–26 dBm
H
i
i
IFO
IFO
generator
generator
Figure 6. Test circuit conversion power gain (PGC) and 3rd-order input intercept point (IIP3)
U2796B
Rev. A3, 10-Oct-00 5 (10)
8765
1234
C
2
3
C
1
C
LO
generator
R = 50
i
10 dB
– 10 dBm
LO
10 dB
U2796B
i
Spectrum
analyzer
R = 50
RF S
V
4
C
93 7761 e i
i
IFO
IFO
Figure 7. Test circuit isolation LO to RF
8765
1234
C
2
3
C
IP3
R
C4
1
C
LO
generator
R = 50
i
10 dB
LO
10 dB
S
V
U2796B
RF
–15 to –5 dBm
–26 dBm
10 dB NWA, E
R = 50
i
Power splitter
i
NWA, S
R = 50
93 7762 e
H
i
i
IFO
IFO
Figure 8. Test circuit isolation RF to LO
U2796B
Rev. A3, 10-Oct-006 (10)
8765
1234
C
2
3
C
IP3
R
N
C4
1
C
LO
generator
R = 50
i
LO
S
V
r
C
U2796B
Noise
source RF
Noise
figure
meter
93 7763 e
IFO
IFO
i
i
Figure 9. Test circuit noise figure
Note:
1. The noise floor of the LO generator might influence the noise figure test result. In order to avoid this,
either a bandpass or a highpass filter with fc fIF should be implemented.
2. If IF output network does not provide sufficient suppression of the LO component, a lowpass filter
should be inserted to avoid overdriving the noise figure meter.
3. For best noise performance 0 dBm LO power level is required.
U2796B
Rev. A3, 10-Oct-00 7 (10)
94 7840 e
Figure 10. S11 RF input impedance
94 7841 e
Figure 11. S11 LO input impedance
U2796B
Rev. A3, 10-Oct-008 (10)
Application Circuit
8765
1234
C
2
3
C
IP3
R
N
C4
1
CLO
S
V
r
C
U2796B
RF
2
R
93 7765 e
IFout
i
i
IFO
IFO
TR8/1
Figure 12. Application circuit
Recommended Values for the Evaluator
C1 and C2 = 150 pF, C3 and C4 = 100 nF. Cr is calculated
for resonance with the balun at fIF, or as a highpass filter
for f LO. The output balun transformer ratio = 8:1 for ZO
= 50 Ω. R2 increases the IF output level and is calculated
from:
R2VS(4,MinimalMinimal5)–V
S(
1
)
I
S(
1
)
For example ,VS (4, 5) = 4 V, VS (1) = 3 V, IS (1) = 2.2 mA
R2 470 Ω, where IS (1) is the current consumption with-
out the mixer stage.
Application Hint
The output transformer at the Pins 4 and 5 can be replaced
by LC circuits as shown in figure 13. Compared to trans-
former, LC circuits save space and are suitable for higher
IF frequencies. When applying one of these solutions, it
has to be checked whether the requirements on noise fi-
gure and gain can be achieved.
The second circuit was dimensioned for approximately
130 MHz and a load resistance of 50 . If, for instance,
the impedance of a subsequent filter is 1 k, the capaci-
tive voltage divider may be left out.
VSVS
L2
L1C2
C1C2R
45
VS
5
RL = 50
39 pF
1 H
220 nH
8.2 pF
10 pF
4
95 9632
Figure 13.
U2796B
Rev. A3, 10-Oct-00 9 (10)
Evaluation Board
93 7826 e
RIP3
C1
Cx
C3 Cr
C2
i
out
n.c.
Figure 14. Evaluation board with application circuit
Package Information
13034
technical drawings
according to DIN
specifications
Package SO8
Dimensions in mm 5.00
4.85
0.4
1.27 3.81
1.4
0.25
0.10
5.2
4.8
3.7
3.8
6.15
5.85
0.2
85
14
U2796B
Rev. A3, 10-Oct-0010 (10)
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It is the policy of Atmel Germany GmbH to
1. Meet all present and future national and international statutory requirements.
2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems
with respect to their impact on the health and safety of our employees and the public, as well as their impact on
the environment.
It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as
ozone depleting substances (ODSs).
The Montreal Protocol (1987) and its London Amendments (1990) intend to severely restrict the use of ODSs and forbid
their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these
substances.
Atmel Germany GmbH has been able to use its policy of continuous improvements to eliminate the use of ODSs listed
in the following documents.
1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively
2. Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental
Protection Agency (EPA) in the USA
3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C (transitional substances) respectively.
Atmel Germany GmbH can certify that our semiconductors are not manufactured with ozone depleting substances
and do not contain such substances.
2.
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 Atmel Wireless & Microcontrollers products for any unintended
or unauthorized application, the buyer shall indemnify Atmel Wireless & Microcontrollers 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.
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Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423
