Signal Recovery 7270

The Signal Recovery 7270 Amplifier sets a new standard for general-purpose DSP lock-in amplifiers. Signal Recovery has taken advantage of the developments in technology since the first DSP lock-in amplifiers were introduced in the early 1990's to update the core design, but made sure that they've included all the best features of their model 7265 and 7280 instruments. The new architecture offers even better specifications in an instrument that is physically much more compact than older designs. The result is a lock-in amplifier of outstanding performance that is easy to use and suitable for all measurements over a frequency range extending from 1  mHz to 250  kHz.

In common with other models in the range, the 7270 model offers much more than just dual phase lock-in detection at the reference frequency of an applied signal. We've included features unique to Signal Recovery instruments such as dual reference and dual harmonic detection, which allow signals at two diffe frequencies to be measured simultaneously. The spectral display mode shows the power spectral density of the input signal, making it easy to avoid interfering signals when selecting a reference frequency. It is now even possible to perform tandem demodulation. In this mode an amplitude-modulated signal at a (high) "carrier" frequency is first demodulated at that frequency. The resulting in-phase output, at short time constant settings, is a signal at the modulating frequency which is then passed forward for detection by a second set of demodulators running at the same modulating frequency. Such detection techniques, which can be used in pump-probe measurements, have until now required two separate instruments with an analog connection between them.

The main ADC sampling rate and the rate at which the analog signal outputs are updated is 1  MSa/s, giving excellent performance when used at short output filter time constant settings, such as in scanned probe measurements. But we've also increased the maximum rate at which data can be stored to the internal curve buffer to 1   µs per point, allowing for the first time direct capture of instrument outputs when using these short time constants. The buffer length has also been increased to 100,000 sets of points, giving recording times of 100  ms at the fastest sampling rates. What's more, in the fast capture mode the length does not need to be divided by the number of outputs being stored, making it possible, for example, to store the full 100,000 points of X, Y and auxiliary ADC1 values at the same time.

The built-in RS232, USB and Ethernet connections allow full operation from a controlling computer. We offer a comprehensive software package, Acquire, that can operate the instrument via any of these interfaces and makes it easy to set up and run complex experiments, such as frequency response measurements, as well as allowing remote control of every instrument function. Users who wish to do their own programming can use our ActiveX control and toolkit (SRInstComms), or free LabVIEW driver, to simplify the task.

Features and Specifications of the Signal Recovery 7270 DSP Lock-In Amplifier include:

• 1 mHz - 250 kHz frequency range
• 2 nV/2 fA - 1 V/1 μA FS sensitivity
• Main ADC and analog outputs update rate of 1 MSa/s
• Large, easy to use color display with comprehensive range of operating modes
• USB, Ethernet and RS232 computer interfaces