Features

gain u003d+2 bandwidth (1400 mHz)

gain u003d+8 bandwidth (450 mHz)

# 8226; output voltage swing: ± 4.2V

Ultra high conversion rate: 4300 V/μs

50 mHz)

Low power: 129 MW

Low -loss power: 0.5 MW

Packaging: SOIC -8, vssop-8, SOT23-6

Application

Very broadband ADC drive

123]

Broadband video line driver

Portable instrument

ARB waveform output drive

OPA685 performance upgrade

Instructions

OPA695 is a high bandwidth, current feedback computing amplifier, which combines excellent 4300-v /μs conversion rate and low input voltage noise, thereby realizing a high -precision, low -cost, high dynamic range (IF) amplifier. OPA695 is optimized for high -gain operations, which is very suitable for providing low distortion high output power in the mid -frequency band in the mid -frequency band, or provides low distortion high output power for the upstream line drive of the cable modem. At a lower gain, a higher bandwidth of 1400 MHz can be achieved, making OPA695 an excellent video cable drive that supports high -resolution RGB applications.

OPA695 low 12.9 mAh power current is accurately adjusted when+25 ° C. The fine -tuning and low temperature drift can reduce the system's ultra -temperature power consumption. Can use optional disable control pins to further reduce system power. Keeping this sales open or keeps at a high position, you can work normally. If it is pulled, the power supply current of OPA695 will be dropped below 170 μA. This power-saving function, plus special single+5V operations and ultra-small SOT23-6 packaging, makes OPA695 an ideal choice for portable applications.

Equipment information

(1), please refer to the appointment appendix at the end of the data table.

Typical features

g u003d+8, RF u003d 402Ω, RL u003d 100Ω, unless there are other instructions.

] Parameter measurement information Differential small signal measurement Detailed description Overview OPA695, see the functional frame diagram below, is an operational amplifier with a current feedback structure verified by time. The advantages of current feedback include unpaid bandwidth limit, fast conversion rate, high signal bandwidth, high -frequency and high -range and large -scale distortion performance amplitude. The application of ordinary current feedback computing amplifiers includes coaxial cable drivers, ADC drivers, video amplifiers and high -frequency increase blocks.

Function box diagram

Feature description Broadband current feedback operation

OPA695 provided in the broadband current feedback computing amplifier A new level of performance. With almost constant communication performance within the width gain range, and the conversion rate of 4300-V/μs, it provides a low-power and low-cost solution for the requirements of high-intervals. Although it is optimized under the gain of +8 V/V (the 50Ω load of 12 dB to the matching) to provide 450 MHz bandwidth, it can support the application of 1 to 40. As a video cable driver with +2, the bandwidth is expanded to 1.4GHz, and the conversion rate supports the highest pixel rate. When the gain exceeds 20, the signal bandwidth begins to decrease, but it still exceeds 180MHz, and the gain is 40V/V (the matching 50Ω load is 26DB). Single+5-V power operation also supports similar bandwidth, but the output power capacity is reduced. For low -speed ( lt; 250 MHz) requirements for output power, please consider OPA691.

FIG. 48 shows the dual-power circuit of DC coupling +8 V/V gain as ± 5-v specifications and typical characteristic curve basis. For the purpose of testing, the input impedance settings are 50Ω, the resistance is connected, the output impedance is set to 50Ω, and the series output resistance is set to 50Ω. The voltage fluctuation reported in the specification is directly measured at the input and output pins, and the load power (DBM) is defined under the matching 50Ω load. For Figure 48 circuit, the total effective load is 100Ω | | 458Ω u003d 82Ω. Disable the control line (DIS) usually keeps opening to perform normal amplifier operations. The disabled line must be asserted to be low to close OPA695. Figure 48 contains a optionComponents. In addition to the commonly used power-to-floor off-coupling container, a 0.01-μF capacitor also includes the two power pins. In the actual PCB layout, this optional additional capacitor usually increases the two harmonic distortion of the bipolar power supply operation by 3 to 6 decibels.

FIG. 49 shows dual-power circuits with DC coupling and gain of -8V/V as a typical characteristic curve foundation. Reverse operations provide several performance advantages. Because the input level does not have a co -mode signal, the conversion rate of the inverter operation is higher, and the distortion performance is slightly improved. Figure 49 includes an additional input resistance RT for 50Ω input impedance to 50Ω. The parallel combination of RT and RG sets input impedance. Figure 48 and Figure 49's non -inverter and inverter applications have benefited from the optimization of bandwidth feedback resistance (RF) values u200bu200b(see setting resistance values u200bu200bto optimize discussions in bandwidth). The typical design sequence is to select the radio frequency value for the best bandwidth, set RG for the gain, and then set RT for the required input impedance. When the gain of the reverse configuration increases, the RG is equal to 50Ω points. At this time, the RT is removed, and the input matching is only set by RG. When RG is fixed to achieve a 50Ω input match, RF increases to increase gain. This quickly reduces the realized bandwidth, such as the reversal gain of the frequency response of -16 in the typical feature curve. For gain gt; 10 V/V (14 dB under the matching load), it is recommended not to reverse the operation to maintain a wider bandwidth.

FIG. 50 shows the circuit configuration of AC coupling, single+5 V power supply, and gain to +8 V/V, which is used for+5V specifications and typical typical typical Basis of characteristic curve. The key requirement for the operation of the broadband single power is to keep the input and output signal swing in the available voltage range of input and output. The circuit in FIG. 50 uses a simple resistor separator from the +5 V power supply (two 806Ω resistors) to the non -switch to input to create a input midpoint bias. Then enter the signal to be coupled to the midpoint voltage bias. The input voltage can swing within the 1.6 volt range of any power supply foot, and the 1.8 volts of input signal range can be provided between the power pins. Adjust the input impedance matching resistor (57.6Ω) used in Figure 50 to provide a 50Ω input matching when the parallel combination of the bias distributor network is included. The gain resistor (RG) is the AC coupling, so that the DC gain of the circuit is +1. This makes the input DC bias voltage (2.5V) is also output. The feedback resistance value has been adjusted from the dual -pole power supply conditions to re -optimizing the flat frequency response to the flat frequency within the range of only+5V. On a+5-V power supply, the output voltage can swing within the 1.0 V range of any one power supply. At the same time, it provides an output current of more than 90 mA, so that the 3-V output is swinging to 100Ω (the maximum 7-DBM under the matching load is the matching load. To. The circuit in Figure 50 shows a blocking capacitor drive 1The output resistance of 50Ω is then driven to a 50Ω load. Alternatively, if the DC current required for the ground load is acceptable, the blocking capacitor can be connected or grounded with the point of the power supply.

FIG. 51 shows the circuit configuration of AC coupling, single+5 V power supply, and gain to -8 V/V, which is used as the basis of only +5 V typical characteristic curve. In this case, the midpoint DC bias of the irreversible input end is also decoupled by the additional 0.1 μF decoupled capacitor. This reduces high -frequency source impedance of input bias current noise. The 2.5V bias voltage on the input pin appears on the reverse input pin. Because the RG is blocked by the input capacitor DC, it also appears on the output pin. One advantage of the inverter operation is that because there is no signal swing at the input level, it can increase the conversion rate and operate to a lower power voltage. To maintain the 1-VPP output capacity, it allows running to 3-V power. Under the+3V power supply, the input co -mode range is 0V. However, for the inverter structure of the current feedback amplifier, even if the input level is saturated, the broadband work remains unchanged.

Figure 50 and the single power test circuit in Figure 50 and 51 display +5 V operation. These same circuits can be used within a single power range of +5 V to +12 V. Running on a single +12 V power supply, the absolute maximum power supply voltage specification is +13 V, which provides sufficient design habits for the typical ± 5%power tolerance.

RF specifications and applications

OPA695 with a high, full power bandwidth and third -order intercept is an ideal intermediate frequency amplifier application. The advantages of broadband computing amplifiers like OPA695 include good (and independent) I/O impedance matching, as well as high reverse isolation. A designer who is accustomed to a fixed gain RF amplifier can only provide 13 mAh power current for OPA695 to obtain almost perfect gain accuracy, higher I/O back losses, and more than 30 dBM (up to 110 MHz) The third -order intercept point. With a considerable degree of design freedom achieved by adjusting the external resistance, OPA695 can use a component to replace a large -scale fixed -gain radio frequency amplifier. In order to understand (as far as the radio frequency placing is concerned), how to use this, first consider the 4-S parameters (see the example circuit of the ± 5-V power supply in Figure 48 and 49, but in a single+5-V to+12-V power supply in Figure 48 and 49 You can also get similar results).