{"product_id":"photo-diode-amplifier","title":"Photo Diode Amplifier","description":"\u003cp\u003eThis small module is a photodiode amplifier. The circuit consists of an OPAMP configured as a\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003etransimpedance amplifier\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003efor amplifying the light-dependent current of the photodiode. A small bias voltage is derived from the positive supply and applied to the op amp’s non-inverting input. This prevents the output from saturating at the negative supply rail in the absence of input current. For this design, the photodiode operates in\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003ephotoconductive\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003emode\u003c\/strong\u003e: exposure to light will cause a reverse current through the photodiode. The diode is connected such that this current causes the OPAMP output voltage to increase. The feedback capacitor C5 helps to maintain stability. This capacitor compensates for the photodiode capacitance at the inverting input of the OPAMP. Finally, in the absence of any photodiode current, the amplifier output will attempt to settle at the voltage applied to the non-inverting input. If the non-inverting input is grounded, the output voltage would ideally be 0V. However, the output voltage can never reach 0V because this is also the value of the negative power supply. Therefore, the OPAMP output will “saturate” near its negative power supply. This condition is undesirable and can delay the amplifier’s response to an input signal. To avoid saturation, a resistor divider R1 and R2 from the positive supply is used to bias the amplifier input above ground. The output swing of this amplifier is from\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003e0.1V to 4.9V\u003c\/strong\u003e. The project was built using\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eOPA320\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eOPAMP which is a new generation of precision, low-voltage CMOS operational amplifiers optimized for very low noise and wide bandwidth while operating on a low quiescent current of only\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003e1.45 mA\u003c\/strong\u003e.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSupply Voltage 5V DC\u003c\/li\u003e\n\u003cli\u003eSupply Current 2mA\u003c\/li\u003e\n\u003cli\u003eInput current 0 – 90μA\u003c\/li\u003e\n\u003cli\u003eOutput: 100mV – 4.9V\u003c\/li\u003e\n\u003cli\u003ePCB Dimensions 21.11 x 15.24 mm\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"dotfry","offers":[{"title":"Default Title","offer_id":47071709397164,"sku":"S105","price":9.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0757\/6436\/7532\/files\/S105A.jpg?v=1787829195","url":"https:\/\/dotfry.com\/products\/photo-diode-amplifier","provider":"dotfry","version":"1.0","type":"link"}