The SR844 is the widest bandwidth lock-in amplifier available. It provides uncompromised performance with a frequency range of 25kHz to 200MHz and up to 80dB of drift-free reserve. The SR844 includes the many features, ease of operation and programmability that you've come to expect from the Stanford digital lock-in amplifiers.

Features:

• 25kHz to 200MHz frequency range
• 80dB dynamic reserve
• Time constants from 100µs to 30ks (6, 12, 18, 24 dB/oct rolloff)
• "No Time Constant" mode (10 to 20µs update rate)
• Auto-gain, -phase, -reserve and -offset
• Internal or external reference
• Two 16-bit DAC's and ADC's
• GPIB and RS232 interfaces

The SR844 uses the same advanced DSP technology found in the SR850, SR830 and SR810 lock-in amplifiers. DSP offers many advantages over analog instruments - high dynamic reserve, low zero-drift, accurate RF phase shifts and orthogonality, and digital output filtering.

The SR844 has both 50Ω and 1MΩ. The 1MΩ is used with high source impedances at low frequencies, or with a standard 10x scope probe. the 50Ω input provides the best RF signal matching. Full-scale sensitivities range from 1Vrms (+13dBm) down to 100nVrms (-127dBm). Up to 60dB of RF attenuation or 20dB of RF gain can be selected in 20dB increments. Gain allocation can be optimised to provide up to 80dB of dynamic reserve.