| 摘要 |
A 90-degree digital phase shift network includes at least two all-pass digital filters which have a phase difference of 90 degrees therebetween. These digital filters are adapted to receive the same signal. Each of the all-pass digital filters has phase characteristics theta ( omega ) given by <IMAGE> where T represents a sampling period, Pi a real number indicative of a filter coefficient, omega the angular frequency, m a weight variable, n'=n/2 (n=even number), n'=(n+1)/2 (n=odd number), n an order of a 90-degree digital PSN, m being a positive value other than 1, and satisfying |2m omega |/|Pi|<1 when omega T is sufficiently lower than 1, while satisfying |-Pi omega T2|/2m<1 when omega T is substantially equal to pi .
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