Abstract: A circuit arrangement for measuring a time interval by evaluating the number of complete cycles, and/or the fraction of a cycle, of a ring oscillator that occur(s) during the time interval to be measured, in which there are provided means to avoid a count ambiguity if the time interval ends at or about the completion of a cycle of the ring oscillator.

Abstract: A mixer system for a direct conversion receiver, the receiver including an RF input path which is divided into I and Q paths for demodulating from the RF signals I and Q signals in phase quadrature with one another, the mixer system including first and second serially coupled mixer means in the I path, third and fourth serially coupled mixer means in the Q path, and a local oscillator providing a plurality of local oscillator signals in phase quadrature with one another to the mixer means, such that the first mixer means receives a local oscillator signal in phase quadrature to the local oscillator signal applied to the second mixer means, and the third mixer means receives a local oscillator in phase quadrature to that applied to the fourth mixer means.