Specifications

1. Bandwidth of the final system should be at least in the range 50kHz to 500kHz. The bandwidth is required for our frequency multiplexed readout. At present the DfMuxs use carriers in the frequency range 200kHZ to 1MHz. The larger the bandwidth the more channels we can use. Given that this is a prototype design we're allowing for a reduced bandwidth.
2. The noise in the bolometer when referred to the output must be greater than or equal to the amplifier noise referred to the output. The signal from the sky is indistinguishable from the Johnson noise (http://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise) produced in the circuitry. Ideally the noise floor of the bolometer readout would be completely dominated by the natural noise of the bolometer, since it is the bolometer noise we are interested in (the signal). Making the two noise sources equal at the output is a compromise.
3. The bolometer has a source impedance in range 0.5-1 Ohm, to ensure that the current is not reduced by the measuring stage, the transimpedance amplifier must have an input resistance of less than 50mOhm
4. The signal/noise ratio ideally is constant across the useful bandwidth - should vary at most by _ % for our prototype and by ___% for a good system
5. The transimpedance of the overall system should remain constant over the useful bandwidth - should vary at most by _ % for our prototype and by ___% for a good system

Constraints produced by specifications

• NoiseContraints
• GainContraints

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This topic: ColdFeedback > WebHome > ColdTransformerOpampSpecifications Topic revision: r8 - 2010-03-04 - KevinMacDermid

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