Bootstrapped low-voltage analog switches

Novel low-voltage constant-impedance analog switch circuits are proposed. The switch element is a single MOSFET, and constant-impedance operation is obtained using simple circuits to adjust the gate and bulk voltages relative to the switched signal. Low-voltage (1-volt) operation is made feasible by employing a feedback loop. The gate oxide will not be subject to voltages exceeding the supply voltage difference. Realistic switches have been simulated with HSPICE. The simulations show that the switch circuits operate very well, even when the supply voltage approaches the technology's threshold voltage.