A voltage-to-current circuit employs low leakage manufacturing process transistor(s) to connect at least one non-controlled terminal (e.g. source, drain, or base of MOSFET) and/or control terminal (e.g. gate of MOSFET) of a low power manufacturing process transistor to a predetermined level such as ground level or power supply voltage level when turning off the low power manufacturing process transistor, so as to connect at least two terminals of the low power manufacturing process transistor to the same voltage level, for avoiding or reducing leakage current of the low power manufacturing process transistor when it is turned off.