Features

Low power; power supply current 800 μA/amplifier; fully stipulated at +2.7 V,+5 V, and ± 5 V power supply; 5V high-speed rapid drop; 80 mix, -3 decibel bandwidth (G G +1); 30V/μS conversion rate; 125ns settlement time to 0.1%; rail -to -track input and output; no phase reversal when the input voltage exceeds 0.5V; Within 20 MV range; low distortion-62 decibel@1 MMH, VO 2 volt P-P-86 decibel@100 kilus, VO 4.6 volt P-P; output current: 15 mAh; advanced options: VOS (maximum value) most (maximum value) maximum value maximum value) 1.5 MV.

Application

High -speed battery power supply system; high group density system; portable test instrument; A/D buffer; active filter; high -speed, settings and demand amplifiers.

General description

AD8031 (single) and AD8032 (dual) single power supply voltage feedback amplifier has 80MHz signal bandwidth, 30V/μs conversion High -speed performance of speed and 125ns stable time. This performance is possible, and the power that consumes less than 4.0 MW at the same time is from a single 5 volt power. These characteristics increase the operation time of high -speed battery power supply systems without affecting dynamic performance.

The product has a real single power supply capacity, with rail -to -rail input and output characteristics, and specifies to be used for +2.7 V,+5 V and ± 5 V power supply. The input voltage range can be extended to more than 500 millollers per track. The output voltage fluctuates within the 20 millivoltage range of each orbit to provide the maximum output dynamic range.

AD8031/AD8032 also provides excellent signal quality Each amplifier's power current is 800 μA; THD is -62 DBC, 2 volts of P-P, 1 meter output signal, 100 kilowatt-86 decibels, 100 kilowatt-86 decibels, 100 kucking, 86 decibels, 100 kucking, 86 decibels, 100 kilo, 86 decibels. 4.6 Volume P-P signal opens +5 volt power. Low distortion and fast stability make them an ideal buffer for single power ADC.

AD8031/AD8032 works on the power supply from+2.7V to+12V and dual power supply up to ± 6V. It is very suitable for widespread application. Consumed high -speed system. AD8031/AD8032 has 8 -core PDIP and 8 -core SOIC units, which can work within the industrial temperature range of 40 ° C to+85 ° C. AD8031A also has a space-saving 5-core SOT-23 unit, and AD8032A has an 8-core MSOP unit.

Absolute maximum rated value

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The stress that is higher than the absolute maximum rated value may cause permanent damage to the device. This is just a stress rated value; the functional operations of the equipment in the operation chapter of this specification or above or any other conditions do not mean. Long -term exposure to absolute maximum rated conditions may affect the reliability of the device.

Maximum power consumption

AD8031/AD8032 that can securely dissipate the maximum power restricted by rising temperature. The maximum safe connection temperature of the plastic packaging device is determined by the glass of the plastic (about 150 ° C). Temporarily surpassing this limit may cause the parameter performance to change due to changes in the stress applied to the mold. The knot temperature that exceeds 175 ° C for a long time will cause equipment failure.

Although AD8031/AD8032 has internal short -circuit protection, this may not be enough to ensure that under all conditions will not exceed the highest cordon (150 ° C). To ensure normal operation, it is necessary to observe the maximum power reduction curve shown in Figure 7.

Typical performance features

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Operation theory

AD8031/AD8032 is a single and dual version of high -speed, low power consumption, voltage feedback amplifier. It has an innovative structure and a maximum limit Improve the dynamic range of input and output. The linear input co -mode range exceeds any power voltage of 200 millivolves, and the amplifier does not display the phase reversal when the power supply exceeds 500 millivoltors. When the driving light load is driven, the output is within the 20 millivoltage range of any power supply; when the driver is as high as 5 mAh, the output is within 300 millivoltage range.

In the process of manufacturing on the simulation device, inc. In the process of super fast complement of the bipolar (XFCB), the amplifier provides an impressive 80MHz bandwidth as a follower, providing 30V/ at the power supply of only 800 Weirean, 30V// The conversion rate of microseconds. The careful design makes the amplifier work under the power supply voltage as low as 2.7 volts.

Input level operation

FIG. 43 shows the simplified schematic diagram of the input level. For the co -mode voltage of up to 1.1V in the positive power supply (a single 5V power supply is 0V to 3.9V), the end current I2 flows through the PNP differential to Q13 and Q17. Q5 is cut off; no bias current is transmitted to the parallel NPN differential to Q2 and Q3. When the common modulus voltage is driven within the 1.1V range of the positive power supply, the Q5 is turned on and the tail flow is paired from the PNP to NPN. In this transition area, the amplifier input current changes the amplitude and direction. Repeated use of the same tail current can ensure that the input level has the same cross -guidance in the two working areas, which determines the gain and bandwidth of the amplifier.

When the co -mode voltageWhen the positive power supply is driven for more than 1V, switch to NPN to provide useful operations for the signal that allows any ends to allow the amplifier to be in the power supply range, and eliminate the possibility of the phase reversal of the input signal of up to 500mV outside any power. The offset voltage will also change to reflect the input -pairing offset in the control. The transition zone is small, about 180 millivolves. These sudden changes in the input -level DC parameters can cause small failures that have adversely affected distortion.

Excessive driver input level

Avoid continuous input differential voltage than 3.4 V, because the input transistor may be damaged. If this is the case, it is recommended to use the input clamp diode.

The voltage of the input pair of collectors is set from the power rail to 200 mv. This allows the amplifier to maintain a linear work when the input voltage exceeds 500 millivolves. The driving input co -mode voltage exceeds the point of the headset into the setting of the transistor in the transmission of the transistor, causing the phase to reverse. This state should be avoided within any time, because when the amplifier is in reverse, it is easy to exceed the maximum allowable input differential voltage.

output level, opening gain and

distortion and power gap

AD8031 with rail transmission and output level. The output transistor works as a public transmission polar amplifier, which provides a large part of the output -driven current and an amplifier open -loop gain.

The output voltage limit depends on the output transistor's need for source or exchanges. For applications with low -driving requirements (for example, a unit gain follower follower driver another amplifier input), AD8031 usually swings within the 20 millivoltage range of any voltage source. With the increase of the required current load, the saturated output voltage is:

: ILOAD is the required load current. RC is an output transistor set electrode resistor.

For AD8031, the hi -resistance of the two output transistors is usually 25Ω. When the current output current with a current load of more than 15 mAh, the base drive current required for the saturation of the driving output transistor reaches the limit, and the output amplitude of the amplifier will be reduced rapidly.

The opening gain of AD8031 decreased linearly with the load resistance near the load resistance, depending on the output voltage. The opening gain is kept in the range of 250 millivolttilum of the positive power supply and 150 millivol to the negative power supply, and then the output transistor is further driven to saturation and decreased.

AD8031/AD8032 amplifier's distortion performance is different from traditional amplifiers. Generally, the distortion performance of the amplifier decreases with the increase in the amplitude of the output voltage.

As a unit gain follower, the output of AD8031/AD8032 shows greater distortion in the peak output voltage area near V ~ 0.7V. ThisThe unusual distortion characteristics are caused by the input level structure, and detailed discussions are discussed in the input level operation section.

Output speeding

When the amplifier tries to drive the output voltage to the level beyond its normal range, the output of the amplifier will occur. After eliminating the drive conditions, the amplifier must return to normal work within a reasonable time. As shown in Figure 45, the AD8031/AD8032 recovers within the negative speed of 100 NS and recovers within the 80 NS of the positive speed.

Drive the capacitance load

The output impedance interaction of the capacitance load and the op amp generates additional delays in the feedback path. This will reduce the stability of the circuit and may lead to unnecessary bells and oscillations. When the amplifier uses a higher noise gain, the given capacitance value will cause less bell.

The capacity load driver of AD8031/AD8032 can be achieved by connecting a low -value resistance on the capacity load. The introduction of series resistance is conducive to isolation of the capacitance load from the feedback circuit, thereby reducing its impact. Figure 46 shows the capacitor driver of the series resistance to the variable voltage gain. As a increase in closed -loop gain, larger phase margin allows greater capacitor loads and less overwhelming. Adding series resistance under a lower closed -loop gain can also achieve the same effect. Figure 46. When the capacitor load driver and a closed -loop gain capacitance load, the frequency response of the amplifier is mainly determined by the rolling of the series resistance and capacitance load.

Application

A 2MHz single -power dual -road dual -router pass filter FIG Power dual -road band -pass filter circuit. By connecting to the non -vertical input of all three computing amplifiers to the resistor division (consisting of two 1kΩ resistors connected between 5V and ground), it is easy to produce a bias level of 2.5V. The bias point is also separated from the ground through 0.1 μF capacitors. The frequency response of the filter is shown in Figure 48.

In order to maintain accurate central frequency, the operational amplifier must have a sufficient loop gain at 2 MM. This requires choosing an operational amplifier, which has a significant and higher unit gain and cross -frequency. The unit gain and cross frequency of AD8031/AD8032 are 40MHz. Multiplying the feedback factors of each op amp will be multiplied by the feed factors of each op amp to obtain the loop gain of each gain level. It can be seen from the feedback network of various oprs circles that the loop gain of each op amp is at least 21DB. The level is high enough to ensure that the center frequency of the filter is not affected by transport bandwidth. For example, if you choose a pourker with a width accumulation of 10 MHz in this application, the central frequency generated will move 20%to 1.6 MHz.

HighPerformance single -power source line drive

Even if AD8031/AD8032 swings near two orbit positions, when the signal has a common modulus level between the power supply and a net empty of about 500 MV per track, the AD8031 has the AD8031 to have Best distortion performance. If you need low distortion in the application of a single power supply to obtain a signal close to the ground, you can use the transmitting pole follow -up circuit at the op amp output end.

FIG. 49 shows AD8031 configuring a single power supply, Gainof-2 line drive. When the output drives a 50Ω line connected to the back end, the total gain from VIN to VOUT is 1. In addition to minimizing the reflection, if the cable is short -circuited, the 50Ω back -end resistance can also protect the transistor from being damaged. The launch follower is located in the feedback circuit, ensuring that the output voltage from AD8031 is kept about 700 millivolves from the ground. Using this circuit, even when the output signal swings within 50 millivolves from the ground, low distortion can be achieved. The circuit was tested at 500kHz and 2MHz.

Figure 50 and Figure 51 display the output signal swing and spectrum at 500 kHz. At this frequency, the peak swinging between the output signal (at VOUT) is 1.95 v (50 mv to 2 V), and THD is -68 db (sfdr -77 db).

Figure 52 and Figure 53 display the output signal swing and spectrum at the 2Ms. As expected, at a higher frequency, the signal quality will decrease. When the output signal has a peak of 1.45 V (swinging from 50 MV to 1.5 V), THD is -55 db (sfdr -60 db).

This circuit can also be used to drive an analog input of a single power high -speed ADC, and its input voltage range reference ground (e.g., 0 V to 2 V or 0 V to 4 V). In this case, there is no need to connect the resistor (assuming that the physical distance from the transistor to the ADC is shorter); therefore, the emission pole of the external transistor will be directly connected to the ADC input terminal. Therefore, the available output voltage of the circuit will double.

The size of the shape