Features

High-speed; 41 MMC, -3 decibel bandwidth; 125 volts/microsecond conversion rate; 80 NS precipitation time; input bias current 20Pa, noise current 10fa/√Hz; input voltage noise 12nv /√Hz; completely specified power supply: ± 5 v to ± 15 V; low incomparable: 1 MHz at -76 dB; high output driving capacity; driver unlimited capacitor load; 50 mAh minimum output current; when the input is in the track on the track There is no phase reversal; 8 lead SOIC is provided.

Application

Central control disk; low distortion filter; hybrid gain level; audio amplifier; photoelectric detector interface; ADC input buffer; DAC output buffer.

General description

AD825 is a super -optimized operational amplifier for high -speed, low cost and DC parameters, making it very suitable for extensive signal regulation and data collection application. AC performance, gain, bandwidth, conversion rate and driving capacity are very stable at temperature. AD825 also maintains a stable gain under different load conditions.

The unique input level has ultra -low input bias current and input current noise. At this high -performance input end, any orbit signal does not cause phase reversal at the output end.

These features make AD825 a good choice as a buffer output by multi -way replica, producing minimum offset and gain errors. The AD825 specifies the operations for dual ± 5V and ± 15V power supply. The flexibility of this power supply and a 6.5 mAh low power supply current have excellent AC characteristics under all power supply conditions, making AD825 very suitable for many demanding applications.

[123 ] Drive capacitance load

internal compensation of AD825, plus its high output current driver, while the driver is extremely high -tolerant load, while the driver is extremely highly capacity load, while the highly capacity load is driven, while the highly capacitance load is driven, while the highly capacitance load is driven, and the highly capacity load is driven, while the highly capacitance load is driven, and the highly capacity load is driven, and the highly capacity load is driven, while the highly capacity load is driven, and the highly capacity load is driven, while the highly capacitance load is driven, and the highly capacity load is driven. Allows excellent signal performance.

Operation theory

AD825 is a low cost, Broadband, high -performance FET input computing amplifier. The AD825 uses a unique input -level design. Even if the input voltage exceeds the power supply voltage, the phase -level reversal will not occur. The output -level design is used to drive a large capacitor or resistance load, which changes very little compared to the empty load conditions.

AD825 (Figure 32) consists of a co -leakage, a common FET input level, and driven the NPN gain level with a matching and co -foundation matching. The output buffer uses the transmitting polar follower in the AB amplifier, which can transport a large current to the load while maintaining the level of low distortion.

The output -level capacitor C enables AD825 to drive heavy capacitor loads. For light loads, the gain of the output buffer is close to the unit. With the increase of the capacitor load, the gain of the output buffer decreases, and the bandwidth of the bandwidth is reduced by adding part of the C to the main pole. With the further increase of the capacity load, the bandwidth of the amplifier continues to decline, maintaining the stability of AD825.

Investment considerations

AD825 has its unique input level to ensure that the signal has no phase reversal as much as possible or even greater than the power voltage. In addition, even if the differential signal is large, the layout of the input transistor considers the function to ensure the function.

The low noise input level requires a larger field effect transistor. Additional capacitors should be considered to ensure stability. When using AD825 design filters, the input capacitance (5-6 PF) of AD825 needs to be regarded as part of the passive network.

Ground and bypass

AD825 is a low input bias current FET amplifier. Its high frequency response makes it very useful in the application, such as photoelectric diode interface, filter and audio circuit. When designing high -frequency circuits, there are some special precautions. The circuit must interconnect, and the resistance should have a low -induced grounding path. The power cord should be bypass to the public line that is near the amplifier pin. It is recommended to use 0.1 μF ceramic capacitors.

Second -order low -pass filter

The second -order Batworth low -pass filter can be used to use AD825, as shown in Figure 33. The current of extremely low bias vehicle recognition numbers AD825 allows the use of large resistance values. Therefore, small electrical tolerance values do not have to worry about generating large offset errors. Low -current noise is another factor that allows the use of large resistors without having to worry about the voltage noise generated.

As shown in the figure, the frequency of the corner is 1 MM. The component selection formula is shown below. Note that the input capacitance of non -inverter input (and inverter input) is 6 PF. As a result, the calculation value of C1 (12PF) was reduced to 6PF.

The frequency response of the filter is shown in Figure 34; high -frequency inhibitors better than 40dB are provided.

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