Abstract: A method and apparatus for applying a test signal to a node of a signal path of an integrated circuit using a parasitic capacitance of the integrated circuit associated with the node. For example, a parasitic capacitance associated with a bond pad may be used to apply a test signal to a signal path. Alternatively, a parasitic capacitance associated with a shielding element may be used to apply a test signal to the signal path.

Abstract: Semiconductor structures with high impedances for use in biasing for applying voltage bias to part of a device. The semiconductor structure comprises a continuous structure having a plurality of regions of a first semiconductor type (n type or p type) material arranged alternately with at least one region of the opposite type. The structure may be formed from polysilicon and may also include a plurality of intrinsic regions arranged between the n and p type regions. The structure forms a composite diode and provides a high impedance.

Abstract: Charge pump circuits having circuit components such as transistors which may be damaged by voltage transients greater than the normal operating voltage levels of the charge pump circuit, such as may be experienced during powering down. The circuit components to be protected are connected in parallel with a leakage element arranged to have a leakage current that is small enough during normal operation to allow the charge pump to operate effectively but which is large enough, during development of a voltage transient, to prevent excess voltage levels being achieved. The leakage element may have a significant leakage current at a voltage less than the breakdown voltage of the circuit component. Suitable leakage elements are poly diodes.

Abstract: A frequency divider, comprising an input for receiving an input clock signal having a first frequency; a divider, for generating an output signal having an instantaneous frequency equal to the first frequency divided by an instantaneous division ratio; and a sequence generator, for generating a sequence of instantaneous division ratios by adding a sequence of instantaneous dither values to an integer value. The instantaneous division ratios in the sequence have a mean value that is equal to an integer desired ratio, but none of the instantaneous division ratios in the sequence is equal to the integer desired ratio.

Abstract: An amplifier especially suitable for use as a reading-head amplifier in a disc drive employing a magnetoresistive sensor. The amplifier is capable of injecting a fixed current into the magnetoresistive sensor and of providing an output signal dependent on the voltage developed across the magnetoresistive sensor as the resistance of the sensor varies in accordance with its magnetic environment.