SBOS479A March 2009 – April 2018 OPA356-Q1
PRODUCTION DATA.
Wide gain bandwidth, low input bias current, low input voltage, and current noise make the OPA356-Q1 a preferred wideband photodiode transimpedance amplifier. Low-voltage noise is important because photodiode capacitance causes the effective noise gain of the circuit to increase at high frequency.
The key elements to a transimpedance design, as shown in Figure 29, are the expected diode capacitance (C(D)), which must include the parasitic input common-mode and differential-mode input capacitance (4 pF + 5 pF), the desired transimpedance gain (R(FB)), and the gain-bandwidth (GBW) for the OPA356-Q1 (20 MHz). With these three variables set, the feedback capacitor value (C(FB)) is set to control the frequency response. C(FB) includes the stray capacitance of R(FB), which is 0.2 pF for a typical surface-mount resistor.