A high-speed folded-cascode OP amplifier with a dynamic switching bias circuit, which enables low power consumption, high gain stably, and a relatively wide dynamic range in low power supply voltages, is proposed. Through simulations, it was shown that the OP amplifier is able to operate at a 10 MHz dynamic switching rate and a dissipated power of 71 % of that observed in continuous operation. It also showed an open loop gain of 51 dB and a 0.996 V output dynamic range which is wider than that in a telescopic OP amplifier. The 10 MHz high-speed switching operation, allowing processing video signals, was confirmed by applying to a switched capacitor non-inverting amplifier with a gain of below 2. The simulation results showed that the output inaccuracy for a switched capacitor amplifier with a gain of below 2 is below 1.5 %, which is practicable. This inaccuracy was caused by the static nonlinearity of the OP amplifier, determined on its limited open loop gain.