low input impedance amplifier

If this is for DC operation (ASCII art):

---------/\\/\\------------------------------ ! ! ! ----!!------ ! IN ----+---!+\\ ! ! ! ! >--+---/\\/\\--+--!-\\ ! ! --!-/ ! ! >------+---------- ! ! GND---!+/ +---!!--- ! \\ / \\ ! GND

Op-amps = TL072 Resistors = 1.1M Capacitors = 50u 25V Mylar

Please suggest more design design requirements, preferably related to the application.

Virtual earth (a.k.a., virtual ground) current to voltage converter:

Resistance sets the I to V ratio, input appears "grounded" over ranges of operation where OpAmp can servo it.

Operational amplifiers are inverting and have high gain (at DC as well as at signal frequencies). Almost all idealizations of op amps add 'fully-differential' and 'high input impedance' and 'low output impedance' to this.

Norton amplifiers (current-input-differencing) like LM3900 have low input impedance BUT that goes with requirement to ensure with suitable external components that the input doesn't get too much current (and burn up) or go negative (and saturate/shut down the amplifier).

Some op amps (like uA741) have 'input offset' pins that amount to a low-impedance input option.

And an inverting-gain connected op amp (ground the (+) pin and use R1 from signal to (-), and R2 from output to (-) ) has the input impedance equal to R1; it can be anything you want.