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2022-09-21 17:24:28
AD8350 is low distortion 1.0 GHz differential amplifier
Features
- High dynamic range
- Output ip3: +28 dbm: R@250 mHz low noise coefficient: 5.9 decibel@250 MMB: [123 123 ]
-AD8350 -15: 15 decibel
-AD8350-20: 20 decibels─3 decibel bandwidth: 1.0 Gigabit Hhe
] - Single power operation: 5 V to 10 V
- Power supply current: 28 mia
- Input/output impedance: 200
- Single -end or differential input driver
-8-lead SOIC packaging and 8-lead formation packaging
Application
-Honeycomb base station-Corphic receiver radio frequency/medium frequency increase block
-Differential A-TO-D drive
-Sound surface wave filter interface
-Single-end to differential conversion
-High-performance video [ 123]
-The high -speed data transmissionProduct description
AD8350 series is a high -performance omnidirectional amplifier, suitable for radio frequency and intermediate frequency circuits, with a frequency of 1,000 MI. The amplifier has an excellent noise coefficient of 5.9 250 MMS. It offers a high output third -order intercept (OIP3) at 250 MMS at 250 MMS. Provide 15 decibels and 20 decibel gain versions.
AD8350 design is used to meet the high performance requirements of the transceiver application. It makes the high dynamic range differential signal chain, which has special linearity and increased coexistence suppression. This device can be used as a universal gain block, A-TO-D drive, and high-speed data interface drive. The AD8350 input can also be used as a single -end to differential converter.
The amplifier can work to 5 volts at 250 MHH, OIP3 is +28 dBM, and the distortion performance is slightly reduced. Broadband width, high dynamic range and temperature stability make this product very suitable for honeycomb, cable television, broadband, instrument and instrument and other applications required for various radio frequency and medium frequency.
AD8350 uses 8 -guide single SOIC packaging and μsoic packaging. It is powered by 5 volts and 10 volts, and the typical current is 28 mAh. AD8350 provides power enlightenment function for power sensitivity applications. The AD8350 uses a high -speed complementary bipolar process with analog device. The device can be used within the temperature range of industrial (-40 ° C to+85 ° C).
Function box diagram
8 -guide SOIC and SOIC package (enable)
典型性能特征——AD8350使用AD8350的应用程序
[ 123] FIG. 1 shows the basic connection of operating AD8350. A single power supply in the range of 5 V to 10 V is required. 0.1 μF capacitors should be used. ENBL pins are connected to the positive electrode power supply or 5 V (when VCC 10 V) for normal operation, and should be pulled to the ground to make the device in the dormant mode. The input and output terminals have DC bias levels at the middle power supply, which should be coupled.
FIG. 1 also shows the input and output impedance balance requirements (resistance or non -merit). When the input and output impedance is 200Ω, the AD8350 should be driven by the 200Ω power supply and loaded by 200Ω impedance. You can also achieve passive matching.
FIG. 2 shows how AD8350 is driven by a single -ended source. Unused inputs should communicate with ground. During the single -ended drive, the differential output voltage will be slightly unbalanced. This will lead to an increase in second-order harmonic distortion (when 50 MHz, VCC 10 V, Vout 1 V p-P, the second harmonic of -59 DBC is measured on AD8350-15).
Unable to match
In practical applications, the AD8350 is likely to use the reactive matching component shown in Figure 3 for matching. The matching component can be calculated in Smetu, or the resonance method can be used to determine the matching network that causes complex co -match matching. In any case, the circuit can be analyzed as a single -end equivalent circuit in order to calculate, as shown in Figure 4.
When the source impedance is less than the load impedance, a boost matching network is required. The typical boost network is shown in the input of AD8350 in Figure 3. For pure resistance sources and load impedance, the resonance method can be used. The input and output impedance of AD8350 can simulate the actual 200Ω resistor when the operating frequency is less than 100 MHz. For signals with a frequency of more than 100MHz, the classic Smith matching technology should be used to handle complex impedance relationships. See Table Ii and Table III in the detailed S parameter data of differential measurement in the 200Ω system.
For input matching networks, the source resistance is less than the input resistance of AD8350. The input resistance of AD8350's pin 1 to 8 is 200Ω. If you use 100 NF capacitors and the minimum signal frequency is greater than 1MHz, the electrical resistance of the AC coupling capacitor CAC should be negligible. If the series of tandem electrical resistance of the network electrocomputer is defined as xs 2πf LS, the parallel electrical resistance of the matching container is defined as XP (2πf CP) –1, then:
For 70 MHz applications with a 50Ω source resistance, assuming the input impedance is 200Ω, or RLOAD RIN 200Ω, then XP 115.5 points ω and xs 86.6 ω, which will generate the following components: [[[[[[[[[[[[[[[[ 123]
For the output matching network, if the output source resistance of the AD8350 is greater than the terminal load resistance, the lower voltage network shown in Figure 3 should be used. For anti -blood pressure matching networks, the computing of series and parallel electrical resistance is as follows:
For 10 MHz applications, the 200Ω output source resistance is AD8350, RS 200Ω, 50Ω load connection, RLOAD 50Ω, and then xp 115.5 points ω and xs 86.6 ω, which will generate the following components:
The curve diagram in Figures 5 and Figure 6 can be obtained. The same result. Figure 5 shows the standardized parallel resistance and standardized source resistance of the voltage matching network, RS LT; RLOAD. After checking, you can find an appropriate electric resistance of the given RS/RLOAD value. Then use the XS RS RLOAD/XP to calculate the series of electrical resistance. The same technology can also be used to design a designed antihypertensive matching network.
The same result can also be found through Smith, as shown in Figure 7. In this example, use parallel container and series inductors to match the 200Ω power supply with 50Ω load. For the frequency of 10 MMC, the same capacitance and inductance value found in the resonance method before will be converted to 200Ω power to match the 50Ω load. When the frequency of more than 100 MHz, the S parameters in Table II and III should be used to explain complex impedance relationships.
After determining the matching network of single -end equivalent circuits, you need to apply matching elements in a differential manner. Candidate and electricity resistance need to be separated in order to eventually balance the network. In the previous example, this is just to divide the series inductance into two equal half, as shown in Figure 3.
gain adjustment
Using multiple technologies can reduce the effective gain of AD8350. Obviously, the matching dexter network will reduce the effective gain, but this requires a separate component, which may be discouraged in size and cost. The attenuator will also increase the effective noise coefficient, leading to a decrease in signal -to -noise ratio. Simple pressure signs can be achieved using the combination of front -stage driver impedance and parallel resistance of the AD8350 input terminal, as shown in Figure 8. This provides a compact solution, but due to the thermal noise contribution of the diversion resistor, the density of the input -end noise spectrum at the AD8350 increases. The input impedance can be dynamically changed by using feedback resistors, as shown in Figure 9. This will be reduced by the reduction of the sterilizer and the AD8350 from the Drived source impedance.Enter impedance to cause similar attenuation of the input signal. However, this technology does not significantly reduce the signal -to -noise ratio because the real resistance compliance network will generate unnecessary heat noise increases.
FIG. 8 shows the typical implementation of the concept of diversion distributor. Due to the decrease in the input impedance of the input impedance of the parallel resistor and the AD8350 input impedance, the attenuation of the input signal effectively reduces the gain. For the frequency of less than 100 MHz, the input impedance of AD8350 can be modeled as a actual 200Ω resistor (differential). Assuming that the frequency is low enough, the parallel power resistance of the input terminal can be ignored, and it is high enough, so that the electrical resistance of the medium -sized AC coupling container can be considered to be neglected.
Among them
Table 1 summarizes the insertion loss of multiple parallel resistance values and the power gain generated. When using formula 1, you need to pay close attention to the source resistance and input impedance. It is necessary to consider their electrical resistance before assuming that the contribution of the input impedance of AD8350 and AC coupling container can be ignored before it is ignored. Figure 10 shows the effective power gain of multiple values of the RSHunt of AD8350-15 and AD8350-20.
gain can be dynamically adjusted by using external feedback resistors, as shown in Figure 9. Effective attenuation is the result of reduced input impedance. It is the same as the diversion resistance method, but there is no additional noise contribution at the device input end. In order to reduce co -modular offset errors, good matching resistors must be used. The mass tolerance resistance should be used together with the symmetrical plate layout to help ensure balance performance. The effective gain of multiple values of external feedback resistors is shown in Figure 11.
The power gain of any two port network depends on the power supply and load impedance. When the motion source and load impedance are not 200Ω, the effective gain will change. AD8350's single -end input and output resistance can be modeling using the following programs:
and
Among them // rfint;
rfext r external feedback;
662Ω of rfint AD8350-15;
1100Ω (for AD8350-20); ] Rint 25000Ωgm 0.066 AD8350-15 MHO;0.110 points of MHO of AD8350-20;
RS R source (single-end);
[1] [1 1]
RL R load (single -end);rin r input (single -end);
rout r output (single -end);The following formula calculations can be used:
The lighter load drives
No need to use 200Ω differential load load to load the output of AD8350.It is usually necessary to try to achieve complex co -matching between the source and the load to minimize the reflection and save power.However, if the AD8350 is driving the voltage response device, such as ADC, the maximum power transmission is no longer required.When the driver load is greater than 200Ω, the harmonic distortion performance is actually improved.The lighter load requires a small current driving capacity at the output stage of the AD8350, thereby increasing linearity.Figure 12 shows the second and third harmonic distortion that improves the differential load resistance.