| 摘要 |
<p>A predistortion system comprises a digital compensation signal processing component (DCSP) (52) which predistorts a wideband input transmission signal to compensate for the frequency and time dependent AM-AM and AM-PM distortion characteristics of a non-linear amplifier (64). The DCSP (52) comprises a data structure (52H) in which each element stores a set of compensation parameters (preferably including FIR filter coefficients) for predistorting the input transmission signal. The parameter sets are preferably indexed within the data structure (52H) according to multiple signal characteristics, such as instantaneous amplitude and integrated signal envelope, each of which corresponds to a respective dimension of the data structure (52H). To predistort the input transmission signal, an addressing circuit (52C-52G) digitally generates a set of data structure indices from the input transmission signal, and the indexed set of compensation parameters is loaded into a compensation circuit (52A, 52B) which digitally predistorts the input transmission signal. This process of loading new compensation parameters into the compensation circuit (52A, 52B) is preferably repeated every sample instant, so that the predistortion function varies from sample-to-sample. The sets of compensation parameters are generated periodically and written to the data structure (52H) by an adaptive control processing and compensation estimator (ACPCE) (70) taht performs a non-real-time analysis of amplifier input and output signals. The ACPCE (70) also implements various system identification processes for measuring the characteristics of the power amplifier (64) and generating initial sets of filter coefficients. In an antenna array embodiment (Figures 33 and 34), a single ACPCE (70) generates the compensation parameters sets for each of multiple amplification chains (64) on a time-shared basis. In an embodiment (Figure 32) in which the amplification chain (64) includes multiple nonlinear amplifiers (60A) that can be individually controlled (e.g., turned ON and OFF) to conserve power, the data structure (52H) separately stores compensation parameter sets for each operating state of the amplification chain (64).</p> |
