Design a photoplethysmograph circuit with a transresistance amplifier, including the filter and gain considerations.
a) Specify the key components of the photoplethysmograph circuit, highlighting the role of the transresistance amplifier.
b) Discuss the design considerations for the filter in the circuit, explaining the type of filter chosen and its parameters.
c) Determine the gain requirements for the circuit and explain how the transresistance amplifier achieves the desired gain.