| 摘要 |
The magnitude of an IQ baseband signal from modulator 101 is limited to allow the use of an efficient and linear power amplifier 103. The limiter comprises a first limiter 107 in which the I and Q signals are each limited separately to constrain the IQ vector to a square. The first limiter feeds a 45 degree rotator 109 and a second limiter 111 similar to the first limiter, whereby the IQ vector is constrained to an octagonal area (figure 6). The rotation may be performed by simple addition and subtraction. This peak reduction technique is simple to implement and may be performed in the analogue (figures 7-10) or digital domains. The second phase rotator 113 is optional and reverses the effect of the first rotator 109. |
