| 摘要 |
<p>The mixer receives a first input signal (X) which is mixed (12,14) with signals at a frequency f0, from a local oscillator. A second input signal is mixed with signals (X1,X2) in quadrature with the LO signals. A summer (22) produces a sum (X3) of the first (X1) and second (X2) quadrature signals and a phase-shifting filter (24) with a transfer function A(f) produces a signal (X3') which provides a delay of 45 degrees at the intermediate frequency, f1. A transfer function B(f) is applied to either the first or second signal to generate a fourth signal (X4). The ratio A(f1)/B(f1) has a modulus equal to the inverse square root of 2 and an argument equal to plus or minus 45 degrees or plus or minus 135 degrees . A second summer (18) produces an output (Y) at the intermediate frequency with a phase representative of the input signal at a communication frequency (fo+ f1) or (f0-f1).</p> |
