Ac_driven_bridge_synchronous_demodulator

Published:2009/7/24 5:29:00 Author:Jessie | From:SeekIC

Figure 4-20 shows a circuit that combines a bridge with a synchronous detector to obtain very high noise rejection capability. Figure 4-21 shows the waveforms. Traces A, B, C, D, E, and F show T1 input, A1 input, LTC1043 clock, A1 output, A2 positive input, and A2 output, respectively. An ac carrier excites the bridge and synchronizes the gain-stage demodulator. In this application, the signal source is a thermistor bridge that detects extremely small temperature shifts in a biochemical microcalorimetry-reaction chamber. To calibrate, adjust the phase pot so that C1 switches when the carrier crosses through zero. LINEAR TECHNOLOGY, APPLICATION NOTE 43, P. 24.



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