Abstract: A switchable impedance circuit and method for maintaining a controlled signal line (e.g. RF transmission line) impedance at a circuit node includes a circuit and method for connecting a switchable impedance in shunt or series, or in a shunt and series combination. The switchable impedance can be selectively switched, e.g. "on" or "off", when the circuit is being powered up or down, or both, so as to maintain the desired, e.g. characteristic, impedance at the node of the signal line to which it is connected, for example by providing the complex conjugate of, or vectorially matching, any complex impedance present at such node, thereby advantageously helping to minimize undesirable transient signal effects, such as circuit ringing or oscillator frequency pulling.

Abstract: A circuit of use as a multiplier or a logic cell and suitable for low voltage operation. At least three differential transistor stages are used, with two of the stages receiving one input signal, such as a data input signal if the circuit is to function as a logic cell and a multiplicand if the circuit is to function as a multiplier. A load is provided for the two stages which is connected to one of the circuit supply voltages. The third differential transistor stage receives a second input signal which is the other multiplicand if the circuit is configured as a multiplier and which is a clock signal if the circuit is configured as a logic cell. Circuitry is provided for controlling current flow through the first and second stages in response to current flow in the third stage. If the circuit is configured as a multiplier, the change in current flow in the first and second stages caused the transconductance of the stages to change so that multiplying action will take place.