7A22

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The 7A22 is a single channel differential vertical amplifier for the 7000 series mainframes, produced from about 1969 to 2000.

Remarkably, the 7A22's input sensitivity reaches down to 10 μV/div. Bandwidth is 1 MHz, the upper 3dB limit can be reduced in ×3 steps down to 100 Hz (to eliminate noise, inter alia), and the lower bandwidth can be raised in ×10 steps from 0.1 Hz to 10 kHz. A separate control optionally supplies an internal DC voltage to offset the DC signal component. Even in the most sensitive ranges (10 μV/div to 10 mV/div), common-mode voltage can be ±10 V. Input resistance is 1 MΩ but for high source resistance DC coupled measurements, one can disconnect the internal gate return resistors of the input FETs, at the cost of disabling the 20mv/div and higher ranges.

Applications include audio, biological signals, etc.

An example application is found in Jim Williams' Application Note 124 – see Appendix D for a comparison of differential amplifiers.

Pictures

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  7A22: 1 kHz, 130 μV_p-p triangle, BW=1 MHz

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  7A22: 1 kHz, 130 μV_p-p triangle, BW=100 kHz

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  7A22: 1 kHz, 130 μV_p-p triangle, BW=10 kHz

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  7A22: 1 kHz, 130 μV_p-p triangle, BW=1 kHz