The OPA2683 provides a new level of performance for dual, very low-power, wideband, current-feedback amplifiers. This CFBPLUS amplifier is among the first to use an internally closed-loop input buffer stage that significantly enhances performance over earlier low-power, current-feedback (CFB) amplifiers. This new architecture provides many of the advantages of a more ideal CFB amplifier while retaining the benefits of very low-power operation. The closed-loop input stage buffer gives a very low and linearized impedance path at the inverting input to sense the feedback error current. This improved inverting input impedance gives exceptional bandwidth retention to much higher gains and improved harmonic distortion over earlier solutions limited by inverting input linearity. Beyond simple high gain applications, the OPA2683 CFBPLUS amplifier can allow the gain setting element to be set with considerable freedom from amplifier bandwidth interaction. This flexibility allows frequency response peaking elements to be added, multiple input inverting summing circuits to have greater bandwidth, and low-power differential line drivers to meet the demanding requirements of DSL.
The output capability for the OPA2683 also sets a new mark in performance for very low-power current-feedback amplifiers. Delivering a full ±4Vpp swing on ±5V supplies, the OPA2683 also has the output current to support this swing into a 100 load. This minimal output headroom requirement is complemented by a similar 1.2V input stage headroom giving exceptional capability for single +5V operation.
The OPA2683s low 1.9mA total supply current is precisely trimmed at +25°C. This trim, along with low shift over temperature and supply voltage, gives a very robust design over a wide range of operating conditions. Further system power reduction is possible using the shutdown feature of the MSOP-10 package.
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