| US 7,551,687 B2 | ||
| Distortion compensating apparatus | ||
| Takayoshi Ode, Kawasaki (Japan); Yasuyuki Oishi, Kawasaki (Japan); Tokuro Kubo, Kawasaki (Japan); Kazuo Nagatani, Kawasaki (Japan); Hajime Hamada, Kawasaki (Japan); and Hiroyoshi Ishikawa, Kawasaki (Japan) | ||
| Assigned to Fujitsu Limited, Kawasaki (Japan) | ||
| Filed on Jun. 10, 2005, as Appl. No. 11/149,730. | ||
| Application 11/149730 is a continuation of application No. 09/737196, filed on Dec. 14, 2000, granted, now 7,012,969. | ||
| Claims priority of application No. 11-372885 (JP), filed on Dec. 28, 1999; and application No. 2000-097092 (JP), filed on Mar. 31, 2000. | ||
| Prior Publication US 2005/0226346 A1, Oct. 13, 2005 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. H04K 1/02 (2006.01) | ||
| U.S. Cl. 375—296 [375/295; 375/285; 375/297; 455/450; 455/126; 330/149; 330/151] | 9 Claims |
| 1. A distortion compensating apparatus for compensating for distortion of a transmission power amplifier, comprising:
a memory for storing distortion compensation coefficients, which are for compensating for distortion of the transmission power
amplifier, in association with power p of a transmit signal;
a predistortion unit for subjecting the transmit signal to distortion compensation processing using a distortion compensation
coefficient that conforms to the power p of the transmit signal;
a DA converter for converting a digital transmit signal, which has been subjected to distortion compensation processing, to
an analog signal and inputting the analog signal to the transmission power amplifier;
a distortion compensation coefficient calculation unit for calculating a distortion compensation coefficient based upon the
transmit signal before the distortion compensation thereof and a feedback signal fed back from an output side of the transmission
power amplifier;
a comparison unit for judging whether the transmit signal, which is subjected to the distortion compensation processing using
the distortion compensation coefficient calculated by said distortion compensation coefficient calculation unit, exceeds a
dynamic range of said DA converter;
a distortion compensation coefficient correction unit for correcting the distortion compensation coefficient in such a manner
that the transmit signal that has been subjected to the distortion compensation processing does not exceed the dynamic range
of said DA converter; and
a distortion compensation coefficient updating unit for updating a distortion compensation coefficient, which has been stored
in said memory, by the distortion compensation coefficient that has been corrected.
|