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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

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Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of
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Simple Switching Regulator Circuit Diagram

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This is the simple switching regulator circuit diagram. The LTC10432 switched-capacitor building block provides nonoverlapping complementary drive to the Ql to Q4 power MOSFETs. The MOSFETs are arranged so that Cl and C2 are alternately placed in series and then parallel. During the series phase, the + 12 V battery`s current flows through both capacitors, charging them, and furnishing load current. 

During the parallel phase, both capacitors deliver current to the load. Ql and Q2 receive similar drive from pins 3 and 11. The diode-resistor networks provide additional nonoverlapping drive characteristics, preventing simultaneous drive to the series-parallel phase switches. Normally, the output would be one-half of the supply voltage, but C1 and its associated components close a feedback loop, forcing the output to 5 V. With the circuit in the series phase, the output heads rapidly positive. 

When the output exceeds 5 V, Cl trips, forcing the LTC1043 oscillator pin, trace D, high; this truncates the LTC1043`s triangular-wave oscillator cycle. The circuit is forced into the parallel phase and the output coasts down slowly, until the next LTC1043 clock cycle begins. Cl`s output diode prevents the triangle down-slope from being affected and the 100-pF capacitor provides sharp transitions. The loop regulates the output to 5 V by feedback controlling the turn-off point of the series phase.

Simple Switching Regulator Circuit Diagram


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