{"product_id":"an-ultra-low-noise-pre-amp-for-audio-applications","title":"An Ultra-Low-Noise Pre-Amp For Audio Applications","description":"\u003cp\u003e\u003cspan\u003eThis compact preamplifier module is designed to amplify small signals from high-source-impedance sensors with minimal added noise. It delivers a midband gain of 60 dB and a flat frequency response from approximately 16 Hz to 43 kHz. The clean roll-off at the corner frequencies produces a natural-sounding filter response well suited to audio applications.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eThe board operates from a single 12 V DC supply by default, with an option for dual-supply operation via component substitution. Screw terminals are provided for signal input (CN2) and output (CN3). A 3-pin header (CN1) accepts the power supply connections.\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch3\u003eSpecs and Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePower supply: 12 VDC (single supply, default)\u003c\/li\u003e\n\u003cli\u003eDual-supply operation supported via optional component population\u003c\/li\u003e\n\u003cli\u003eVoltage gain: 1000 V\/V (60 dB)\u003c\/li\u003e\n\u003cli\u003eFrequency response: ~16 Hz to 43 kHz (−3 dB)\u003c\/li\u003e\n\u003cli\u003eInput stage IC: JFE150 JFET, SOT23-5 package\u003c\/li\u003e\n\u003cli\u003eOutput stage IC: OPA202 precision op-amp, SOIC8 package\u003c\/li\u003e\n\u003cli\u003eScrew terminals (5.08 mm pitch) for signal input and output\u003c\/li\u003e\n\u003cli\u003e3-pin male header (2.54 mm pitch) for power input\u003c\/li\u003e\n\u003cli\u003eOn-board power LED (D1)\u003c\/li\u003e\n\u003cli\u003eMounting holes: 4 × M3\u003c\/li\u003e\n\u003cli\u003ePCB dimensions: 54.93 × 29.05 mm\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe input signal is AC-coupled through C8 (10 µF) to the gate of U1 (JFE150). Resistor R7 (1 MΩ) sets the DC gate bias.\u003c\/p\u003e\n\u003cp\u003eThe JFE150's drain current is proportional to the gate voltage: I\u003csub\u003eDS\u003c\/sub\u003e\u003cspan\u003e \u003c\/span\u003e= g\u003csub\u003em\u003c\/sub\u003e\u003cspan\u003e \u003c\/span\u003e× V\u003csub\u003eGS\u003c\/sub\u003e. Therefore, it is an effective current-controlled transconductance element. The DC drain bias is set by R5 (4.02 kΩ), which is connected to the +VS rail.\u003c\/p\u003e\n\u003cp\u003eThe OPA202 (U2) is configured as a transimpedance amplifier. Its inverting input is driven by the JFET drain current, and feedback resistor R13 (1 MΩ) sets the transimpedance gain.\u003c\/p\u003e\n\u003cp\u003eThe non-inverting input is biased by a resistor divider (R2 and R4, both 110 kΩ) that sits at mid-supply (~6 V) in single-supply mode. This V\u003csub\u003eBIAS\u003c\/sub\u003e\u003cspan\u003e \u003c\/span\u003eshifts the OPA202 output DC level to approximately 6 V, keeping it within its linear range on a single rail.\u003c\/p\u003e\n\u003cp\u003eOutput isolation resistor R6 (49.9 Ω) improves stability when driving capacitive loads above 1 nF. It can be removed if no capacitive load drive is required.\u003c\/p\u003e\n\u003cp\u003ePower-supply filtering is handled by a ferrite bead (R16, 600 Ω at 100 MHz) in series with the supply rail, supplemented by bulk (C1, 47 µF tantalum) and bypass capacitors (C2, C3, 100 nF each).\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"dotfry","offers":[{"title":"Default Title","offer_id":47201959346348,"sku":"A132","price":18.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0757\/6436\/7532\/files\/A132.jpg?v=1789381526","url":"https:\/\/dotfry.com\/products\/an-ultra-low-noise-pre-amp-for-audio-applications","provider":"dotfry","version":"1.0","type":"link"}