Features

High -speed

250 MHz -3 DB bandwidth (G +1)

3000 V/s conversion rate The stable time is 0.1%

2V steps of 1.8ns rising time

Low power

3.5 mA/AMP power supply current (35 mW/AMP)

[ 123] Single power operation

Fully specify +5 V power supply

Good video specifications (RL 150, G +2)

The gain flat is 0.1 db to 30 MHz

0.04%Differential gain error

0.10 Differential phase error low distortion

-5 MHz is 78 dbc THD

-20MHz is 61 dbc. THD

50 mAh's high output current

provides 14 -line PDIP, SOIC and CERDIP

Image scanner

Active filter

Video switch

Special effect

General description

AD8004

is a four -way, low power consumption , High -speed amplifier, designed for single power supply or dual power supply. It uses a current feedback structure and has a high conversion rate of 3000V/ms, making AD8004 an ideal choice pulse for processing large amplitude. In addition, the gain flatness of the AD8004 is 0.1db to 30MHz, and the differential gain and phase errors are 0.04%and 0.10∞, respectively. This makes AD8004 suitable for video electronic devices such as cameras and video switches.

AD8004 provides a low power consumption of 3.5 mAh/amplifier, which can run on a single +4 V to +12 V power supply, and can provide upper load current up to 50 mAh. All these are provided in a small 14 -line DIP or 14 -line SOIC package. These features make the amplifier ideal for portable and battery power supply applications. In these occasions, the size and power are crucial. AD8004's excellent 250MHz bandwidth and 3000V/ms conversion rate make it apply to universal high -speed applications that require up to ± 6V and 4V to 12V. In N and R components, the industrial temperature range of AD8004 is -40∞c to+85∞C, while the military temperature range of the Q component is -55∞c to+125∞C.

Wiring chart

Order Guide

AD8004 The maximum power that can be securely dissipated by related knot temperature rises High limit. The maximum safety knot temperature of the plastic packaging device is determined by the glass -based transition temperature of the plastic, which is about+150 ° C. Temporarily surpass the limit may cause the parameter performance to change due to changes in the stress applied to the mold. The knot temperature exceeding+175 ° C for a long time can cause equipment failure.

Although AD8004 has internal short circuit protection, this may not be enough to ensure that in all cases, it will not exceed the highest knot temperature. To ensure normal work, maximum rated power must be observed.

Pay attention to safety

Static discharge sensitive device. The electrostatic charge up to 4000V is easy to accumulate on the human body and testing equipment, and can be discharged without testing. Although AD8004 has a proprietary ESD protection circuit, permanent damage may occur on devices suffering from high -energy static discharge. Therefore, it is recommended to take appropriate ESD prevention measures to avoid decline in performance or loss of function.

Typical performance characteristics-AD8004

Operation theory AD8004 is a member of a new high -speed current feedback (CF) amplifier series. It provides new bandwidth, distortion and signal swing capacity. Its wide dynamic range ability is due to a complementary high -speed bipolar process and a new design architecture. AD8004 is basically two levels (Figure 30) instead of traditional single design. Both stages have the characteristics related to current feedback amplifiers on demand. This makes the ratio of static current to dynamic performance to unprecedented levels. The important feature of the conversion rate and full power bandwidth benefits from this performance. In addition, the second -level gain has buffered the impact of load impedance, which greatly reduces distortion. The data table of the AD8011 provides a complete discussion of this new large -device structure. This discussion involves only the basic principles of operation.

DC and communication characteristics

Like the traditional computing amplifier circuit, the DC closed loop gain is defined as:

irreversible operation

Anti -anti Transfer operation

Considering the more accurate relationship of the increasing increasing gain error is:

Used for reversal (g is negative)

G is positive)

In these equations, the opening voltage gain (Ao (s)) is the voltage feedback amplifierCombined with the current feedback amplifier, the ratio of the output voltage to the differential input voltage. Open -loop cross -resistant gain (to (s)) is the ratio of output voltage to inverter input current, which is suitable for current feedback amplifiers. In TPC15 and 18, the relationship curve of AD8004's open loop voltage gain and open -loop cross -resistance gain and frequency of frequency is drawn. These curves and basic relationships can be used to predict the first performance of AD8004. Under the low -closed cycle gain, item (RF/To (S)) controls the frequency response characteristics. This gives the result of a constant bandwidth and gain, which is a common feature of current feedback amplifier.

Select 1K RF as the nominal value to obtain the best frequency response, and reach the acceptable peak when the gain is+2/-1. From the above relationship, it can be seen that under the high closed -loop gain, reducing radio frequency has the effect of increasing closed -loop bandwidth. Table 1 gives the best value of various gains of RF and RG.

Drive capacitance load

AD8004 is mainly used to drive non -reactive loads. If the driver load with a capacitor element is required, the best stable response is obtained by adding a small series resistance, as shown in Figure 6. The attachment shows the best value of RSERIES and capacitance load. It is worth noting that when the driving large -capacity capacitance load is driven, the frequency response of the circuit will be controlled by the passive rollover of RSeries and CL.

Optimized plane degree

Film scale gain flat and -3DB bandwidth is affected by the following factors. The feedback selection is the normal choice of current feedback amplifier. In addition to gain +1, AD8004 can be adjusted to maximum flatness with a moderate closed loop bandwidth, or a moderate peak frequency response with a greater bandwidth. Figure 8 shows the effect of three uniform radiation changes on gain +1 and gain +2. Table 1 shows the recommended component value of the maximum flat frequency response and faster peak frequency response.

Printing circuit board parasites and device lead frame parasites also control the fine level of fine scale. The AD8004R packaging provides superior parasites compared to N packaging because of its small lead framework. In the printed circuit board environment, parasitic effects such as two parallel and vertical flat conductors in the comparison of the PC plates in the harmonious area will lead to the extension of bandwidth and/or peak increases. In non -mutual gain, the impact of additional capacitors on seeking and knotting is far more significant than reverse gain. Figure 9 shows an example. Note that only 1 PF additional capacitance will cause about 70%of the bandwidth expansion and gain +2 extra peak. For reverse gain –2,5 pF additional conjunction capacitors, the bandwidth expansion has caused 10%of the bandwidth.

Additional output capacitance load can also lead to bandwidth expansion and peak. The smaller the resistance load in the next stage, the more obvious the effect. Figure 10 shows the gain of direct output capacitance loadThe influence of +2 and -2. For these two gains, CLOAD is set to 10 PF or 0 PF (without additional capacitor load). For the four records in Figure 10, the resistance load is 100. Figure 11 also shows the capacitance load effect when the output resistance load is lighter. Please note that even if the bandwidth is expanded by 2 ￥, the flatness will be significantly reduced.

Drive single power supply A/D converter

New CMOS A/D The converter puts forward higher requirements for the amplifier driving them. Higher resolution, faster conversion rate, and irregularity characteristics of the input switch irregularities. In addition, these equipment uses a single+5V power supply to supply power, and the power consumption is low, so it is very important for good single power supply and low power consumption. AD8004 is very good to drive this new type of A/D converter.

FIG. 12 shows a circuit using AD8004 to drive AD876. This is a single power supply, 10 -bit, 20 millisecond/second A/D converter, only 140 MW. AD8004 is used for level conversion and driving. Compared with the signal generator drive, the performance of A/D has not decreased.

The analog input span of AD876 is 2V, and the center is about 2.6V. The resistance network and bias voltage provides the level offset and gain of the 3.6V to 1.6V range that the 0 V to 1 V input signal is converted to AD876.

The input bias of the AD8004's non -inverted input is 1.6V DC power, so that the reverse input is 1.6V DC power to achieve the linear work of the amplifier. When the input is 0 V, there are 3.2 mA through R1 (1.6 v/499 u0026#8486;) to flow out. R3 has a 1.2 mA current flowing into the harmony (3.6 v -1.6 v)/1.65 k u0026#8486;. The difference between the two currents (2 mia) must flow through R2. The current flows to the sequentialness and requires the output to be 2V or 3.6V higher than the end.

When the input is 1 V, 1.2 MA flows into the harmony through R3, and 1.2 mA flows out through R1. These current balance, no current flows through R2. Therefore, the output voltage is the same or 1.6V as the inverter input.

The input end of AD876 has a series MOSFET switch, which is opened and closed at the sampling rate. This MOSFET is connected to a capacitor inside the device. MOSFET's ditbal impedance is about 50Ω, and the capacitance is kept about 5PF.

In the worst case, the input voltage of AD876 will change the full marking value (2V) within a sampling cycle. When the input MOSFET is turned on, the output of the computing amplifier will be connected to the charged capacitor with the charged charging through the series resistance of the MOSFETOn the device. Without any other series resistance, the instantaneous current flowing will be 40 mAh. This will lead to the operational amplifier that solves the problem.

100 u0026#8486; series resistors restricted the current flowing current of MOSFET at about 13 mA. This resistance should not be too large, otherwise it will affect high -frequency performance.

The sample MOSFET of AD876 closed only half or 25ns in each cycle. It takes about 7 time constants to stabilize to 10 bits. 100 u0026#8486; series resistors and 50 u0026#8486; Dit resistance and keep the capacitor generate 750 PS time constant. These values u200bu200bleave a comfortable room for settlement. Compared with the use of signal generator drivers, the use of the combination of computing amplifier A/D is the same, indicating that the stability of the operation amplifier is fast enough.

In general, AD8004 provides sufficient buffer for the AD876 A/D converter without introducing more distortion than the A/D converter itself.

Objectives for layout

The high -speed performance requirements of AD8004 are required to pay close attention to the circuit board layout and component selection. Table 1 shows the recommended component value of AD8004, Figure 14-16 shows the layout of the AD8004 assessment board (14 DIP and SOIC). The choice of correct radio frequency design technology and low parasitic elements is necessary.

PCB should have a floor, cover all the unused parts on the side of the circuit board component to provide a low impedance grounding path. The ground floor should be removed from the area near the input pins to reduce the messy capacitance.

The film -type capacitor is applied to the power sources (see Figure 13). One end should be connected to the ground layer, and the other end should be within 1/8 of each power inserted. In addition (4.7 μF to 10 μF) 钽 electrolytic container should be connected parallel. Tube feet to minimize the wondering capacitance of the node. When working at low and non -reversal gain, capacitors greater than 1PF will significantly affect high -speed performance. Examples of an additional reverse input capacitor.

Band -line design technology is applied to long signal channels (greater than about 1 ""). These devices should be designed as appropriate system characteristics impedance and are connected appropriately at each end.

Note

1. The list of resistance is 1%tolerance.

2. Select RT for the 50Ω feature input impedance.