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U2796B
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
D Supply-voltage range: 2.7 V to 5.5 V D Excellent isolation characteristics D Low current consumption: 3.2 mA without RIP3 D IIP3 programmable D Input frequency operating range up to 2 GHz D RF characteristic nearly independent of supply voltage
Benefits
D Stand-alone product D Low current consumption extends talk time D 3-V operation requires only small space for batteries
Block Diagram
RFI 2 3 BPC Mixer 5 IFO 4 IFO
Duty cycle control loop
Buffer
Voltage regulator
6,8
7 LO i
1 VS
93 7758 e
Figure 1. Block diagram
Ordering Information
Extended Type Number U2796B-MFP U2796B-MFPG3 Package SO8 SO8 Tube Taped and reeled Remarks
Rev. A3, 10-Oct-00
1 (10)
U2796B
Pin Description
VS RFi BPC IFO
93 7820 e
Pin 1 2 3 4 8 7 6 5 GND LOi 3 GND IFO 4 5 6 7
Figure 2. Pinning
Symbol VS RF BPC IFo IFo GND LOi GND
Function Supply voltage RF input and IIP3 programming port Bypass capacitor IF output IF output Ground Local oscillator input Ground
1 2
8
Absolute Maximum Ratings
Parameters Supply voltage Input voltage Junction temperature Storage temperature Pin 1 Pins 2, 3, 4, 5 and 7 Symbol VS Vi Tj Tstg Value 6 0 to VS 125 -40 to +125 Unit V V C C
Operating Range
Parameters Supply-voltage range Ambient temperature Pin 1 Symbol VS Tamb Value 2.7 to 5.5 -40 to +85 Unit V C
Thermal Resistance
Parameters Junction ambient SO8 Symbol RthJA Value 175 Unit K/W
Electrical Characteristics
Test conditions (unless otherwise specified): VS = 3 V, fLO = 900 MHz; IM = 1.2 mA, Tamb = 25C. System impedance ZO = 50 Parameters Supply voltage Supply current Conversion power gain RIP3 = R, Test conditions / Pin Pin 1 Pin 1 RL = 3 k, RIP3 = R fLO = 900 MHz fLO = 1700 MHz fIF = 45 MHz Symbol VS IS PGC Min. 2.7 2.8 3.2 9 9 Typ. Max. 5.5 3.7 Unit V mA dB
Figure 4
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Rev. A3, 10-Oct-00
U2796B
Electrical Characteristics (continued)
Parameters Isolation LO spurious at RFin RF to LO Figure 6 Fi Operating frequencies RF frequency LOin frequency IFout frequency Input level RF input (-1 dB comp.) 3rd-order intercept point LO input Impedances RF input LO input IF output Pin 2 Pin 7 Pins 4 and 5 PiLO = 0 dBm, RL u 3 k fLO = 900 MHz fLO = 1700 MHz Pin 7 ZiRF ZiLO ZoIF 25 50 u10 k// 0.9 pF 9 12 VSWRLO
Test conditions / Pin PiLO = -10 dBm Figure 5 Pin 7 to 2 PiRF = -25 dBm Pin 2 to 7 fLO = 900 MHz fLO = 1700 MHz Pin 2 Pin 7 Pins 4 and 5 RL = 50 , Pin 2
Symbol ISLORF ISRFLO
Min.
Typ.
Max. -35
Unit dBm dB
30
40 20
RFi LOi IFo PiRF IIP3 PiLO -15 -4 -6
2000 2000 300
MHz MHz MHz dBm dBm
PiLO = -10 dBm, RIP3 = R Figure 2 Pin 2 Pin 7
0
dBm
Noise figure (DSB) Figure 7 i Voltage standing wave ratio LO
NF50
dB
1.3
2
Note: IM = Internal mixer current (see figure 3)
3.5 3.0 IIP3 ( dBm ) 2000
93 7827 e
8 5 2
IM ( mA )
2.5
2.0 1.5 1.0 0 400 800 1200 1600
-1 -4 -7 1 2 IM ( mA ) 3
93 7825 e
RE ( W )
Figure 3. Mixer current (IM) versus RE
Figure 4. Third-order input intercept IIP3 point versus IM
Rev. A3, 10-Oct-00
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U2796B
IFO 5 4 LO buffer
3 IM 2 RE
LOi
7
RFi
93 7759 e
Figure 5. Mixer circuitry
f 1= 958.5 MHz 1. RF generator Ri = 50W LOi -10 dBm C1 8 10 dB 7 6 5 IFO N Cr 10 dB
f
= 900 MHz LO LO generator Ri = 50W
Power splitter
RFi 10 dB
U2796B
Spectrum analyzer Hp 70908 A R = 50W i
10 dB 1 -26 dBm 2. RF generator R = 50W i f = 958.55 MHz 2 2 3 C3
IFO 4
C4 C2 1mH RIP3 VS
93 7760 e
Figure 6. Test circuit conversion power gain (PGC) and 3rd-order input intercept point (IIP3)
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Rev. A3, 10-Oct-00
U2796B
93 7761 e
LOi - 10 dBm C1 8 7 6 5 IFO 10 dB
LO generator Ri = 50 W
U2796B
Spectrum analyzer Ri = 50 W C2 10 dB RFi
Figure 7. Test circuit isolation LO to RF
1
2
3 C3
IFO 4 C4 VS
LO generator Ri = 50 W
Power splitter 10 dB 10 dB NWA, E R i = 50 W
-15 to -5 dBm
LOi C1 8 7 6 5 IF O
U2796B
1
2
3 C2
IF O 4
NWA, S R i = 50 W 10 dB
C3 -26 dBm RF i 1 mH R IP3
C4 VS
93 7762 e
Figure 8. Test circuit isolation RF to LO
Rev. A3, 10-Oct-00
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U2796B
LOi LO generator R i = 50 W
C1
8
7
6
5 IFO N Cr Noise figure meter
U2796B
1
2
3 C3
IFO 4
Noise source RFi
C2
C4 RIP3
VS
93 7763 e
Figure 9. Test circuit noise figure
Note: 1. 2. 3. 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 u fIF should be implemented. 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. For best noise performance 0 dBm LO power level is required.
6 (10)
Rev. A3, 10-Oct-00
U2796B
94 7840 e
Figure 10. S11 RF input impedance
94 7841 e
Figure 11. S11 LO input impedance
Rev. A3, 10-Oct-00
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U2796B
Application Circuit
C1 8 7 LO i
6
5 IFO Cr N IFout TR8/1
U2796B
1 C2 RFi
2
3 C3
IFO 4
R2 RIP3
C4 VS
93 7765 e
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 fLO. The output balun transformer ratio u = 8:1 for ZO = 50 . R2 increases the IF output level and is calculated from: V (4, MinimalMinimal5) - V S (1) R2 + S I S (1 ) For example ,VS (4, 5) = 4 V, VS (1) = 3 V, IS (1) = 2.2 mA R2 [ 470 , where IS (1) is the current consumption without the mixer stage. the impedance of a subsequent filter is 1 kW, the capacitive voltage divider may be left out. VS L1 L2 VS
95 9632
C2
C1 4 5
C2
R
Application Hint
The output transformer at the Pins 4 and 5 can be replaced by LC circuits as shown in figure 13. Compared to transformer, 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 figure and gain can be achieved. The second circuit was dimensioned for approximately 130 MHz and a load resistance of 50 W. If, for instance, 1 mH
VS
10 pF 8.2 pF 4 220 nH 5
Figure 13.
RL = 50 W 39 pF
8 (10)
Rev. A3, 10-Oct-00
U2796B
Evaluation Board
Cx n.c. C1
C3
Cr
RIP3
C2
i
93 7826 e
Figure 14. Evaluation board with application circuit
Package Information
Package SO8
Dimensions in mm
5.00 4.85 1.4 0.4 1.27 3.81 8 5 0.25 0.10 0.2 3.8 6.15 5.85 5.2 4.8 3.7
technical drawings according to DIN specifications 13034
1
4
Rev. A3, 10-Oct-00
out
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U2796B
Ozone Depleting Substances Policy Statement
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. Data sheets can also be retrieved from the Internet: http://www.atmel-wm.com
Atmel Germany GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423
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Rev. A3, 10-Oct-00

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