Fast Bipolar Analog Switch Circuit
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Switch circuit A illustrates an analog switch technique for bipolar integrated circuits useful for switching low impedance sources in times as small as nanoseconds, and worst-case offsets less than millivolts. Circuit A is both temperature and beta compensated, has TTL (transistor-transistor logic) compatible inputs, and can operate over a wide range of power supplies including ground up as well as +/- voltages. Transistor T10 generates a current of value '2I' which can then be selected by twin tailed pair T11 and T12 to activate current mirror T1 and T2. This current is presented to node '1' and splits equally between diodes D11 and D12. Transistor T9 generates a current of value 'I' which passes through diode D12, thus guaranteeing this equal split at '1'.