8.2.1.2 Detailed Design Procedure

To achieve a maximally-flat, second-order Butterworth frequency response, the feedback pole should be set to:

Equation 2.

Use Equation 3 to calculate the bandwidth.

Equation 3.

For even higher transimpedance bandwidth, consider the high-speed CMOS OPA380 (90-MHz GBW), OPA354 (100-MHz GBW), OPA300 (180-MHz GBW), OPA355 (200-MHz GBW), and OPA656 or OPA657 (400-MHz GBW).

For single-supply applications, the +INx input can be biased with a positive dc voltage to allow the output to reach true zero when the photodiode is not exposed to any light, and respond without the added delay that results from coming out of the negative rail; this configuration is shown in Figure 37. This bias voltage also appears across the photodiode, providing a reverse bias for faster operation.

1.

NOINDENT:

C_(FB) is optional to prevent gain peaking. C_(FB) includes the stray capacitance of R_(FB).

Figure 37. Single-Supply Transimpedance Amplifier

For additional information, refer to the Compensate Transimpedance Amplifiers Intuitively Application Report.