The Stanford Research SR445 is a four-channel DC-coupled voltage preamplifier engineered for high-speed, low-level signal amplification from DC to 350 MHz. Each channel delivers a fixed gain of 5 V/V with the ability to cascade multiple channels for higher gains up to 625 V/V using four SR445 units. The preamplifier achieves exceptional input noise performance at 2.8 nV/√Hz and maintains <50 µVrms noise referenced to input across its full bandwidth.
Technical Specifications
• Bandwidth: DC to 350 MHz (−3 dB)
• Voltage Gain: 5 per channel; cascadable to 25, 125, or 625 with multiple units
• Input Noise: 2.8 nV/√Hz; <50 µVrms (input-referred)
• Input Impedance: 50 Ω standard; Channel 1 selectable to 500 Ω or 1 MΩ (SR445A)
• Output Impedance: 50 Ω
• Rise/Fall Time: 1.2 ns (1 ns on SR445A model)
• Propagation Delay: 2.2 ns per channel (2.7 ns on SR445A)
• Recovery Time: <4 ns for 20× overload (3 ns for 10× on SR445A)
• Input Operating Range: ±200 mV
• Output Operating Range: ±1.0 V
• Input Offset: ±50 µV (adjustable)
• Temperature Stability: 10 µV/°C (0 to 50 °C, input-referred)
• Crosstalk: −60 dB
• Input Protection: ±50 V for <1 µs
• Output Clamp: ±1.6 V
• Output Overload Detect Threshold: ±1.3 V
• Power Consumption: 10 W or 16 W
– Key Features
• Four independent channels with BNC female connectors
• DC accuracy and low-noise design for precision signal conditioning
• Selectable input impedance on Channel 1 for enhanced flexibility
• Fast transient recovery and overload detection
• Compact form factor compatible with modular instrument racks
– Typical Applications
Photon counting, fast timing measurements, and broadband data acquisition systems. Ideal for amplifying signals from photomultiplier tubes and fast photodiodes where low noise and high-speed response are critical.
– Compatibility & Integration
Operated via SR445 DC Power Supply/Preamplifier Mainframe (±15 V DC). Accepts AC mains input at 100/120/220/240 VAC, 50/60 Hz. All signal connections use standard BNC connectors.
